New Life Games Tech Forums

Fixed: MK3 Ultimate
Symptom: Dead

Physical inspection of the board turned up a large (20 gauge!) wire patch on the EPROMs. Replaced that patch with a 30 gauge Kynar wire wrap wire patch. Found one other gouged trace that was broken in 2 places and gouged off the board by what appeared to have been a huge soldering iron. Board booted but had a ROM error. Replace ROM U132. Game played but had scratcy audio. Resoldered the audio output IC as it had been physically hit and the solder joints had cracked.

Fixed: NBA Jam
Symptom: Scratchpad RAM Error

Board would power up with a Scratchpad RAM Error for UJ7. Replaced the bad chip, a 44256 DRAM, with a socketed replacement. Board would then power up and run but would intermittantly give an error on Video RAM UA11.

Replaced the VRAM IC at UA11 - part # MT42C8128, a 256 x 8 SAM + 128K x 8 RAM dual port video RAM chip. Chip is hard to find but can be found on some old Sun Microsystems frame buffer (video) cards from the early 90s. (In this case a Weitek Power 9000 based card by Megatek)

Ran board through the built-in burn-in tests and played a couple of games.

Model: Ms. Pac Man
Symptom: Garbage on screen

Replaced the ROM at location 6H. It had 5 pins broken off of it and was half way out of the socket. Straightened the pins on the V-RAM addresser daughterboard and reinserted it. It had come loose in shipping. Replaced the zip tie holding the daughterboard in place.

The ROMs on Ms. Pac Man are 2532 and NOT 2732.

To retrofit a 2732 you must rewire 3 pins.

2532:
18: CE*
20: Vpp
21: A11

2732:
18: A11
20: CE*
21: Vpp

This can be done by stacking 2 sockets. make the wiring change between the 2 sockets so the EPROM fits in and it all fits into the board.

Model: Galaxian
Symptom: Large color stripes on screen

Board was missing the U and W ROMs. Burned replacement 2716 EPROMs to bring the CPU to life. Large color stripes would change periodically. The ROMs at J1 and L1 were bad. Burned replacement 2716 EPROMs and the board showed a perfect screen.

Model: Galaxian
Symptom: White screen

Game gave a full white screen and no video artifacts. CPU was rebooting itself and the data lines were in a repeating loop for signals. Replaced bad ROM at Z. Pin 13 was broken on the chip.

Model: Ms Pac Man
Symptom: Rebooting at random

Replaced the CPU socket and socket J1 for the ribbon cable on the daughterboard.

Model: Ms Pac Man
Symptom: Will not boot. Single glitching character on screen.

Ms. Pac Man will normally cycle through characters while doing a self test. This board was stuck on 1 character but was glitching that character continuously.

Replaced bad ROM at 6J and the board would try to boot but come up wtih garbage on screen.

Replaced a bad 2114 SRAM to finish the repair.

Model: Pac Man
Symptom: Garbage on screen. Screen is flipped. No audio.

Board had squished looking blobs for ghosts, text, and fruit. The maze looked as if it were Atari 2600 quality. Very blocky.

Replaced a 74LS174 at 1H to fix the garbage graphics. Pin 9 on it was dead. Replaced 74LS259 at 8K to fix the flipped screen problem. This chip also controls the 74LS273 at 2M for audio but now the speaker would output garbage noise. Replaced the 74S89 RAM IC at 2L to fix the sound problem.

Model: Pac Man
Symptom: Garbage on screen. Dead.

4 ROMs failed checksum. Burned new EPROMs for 5E, 5F, 6H, and 6J and tested the board.

Model: Pac Man
Symptom: Dead, Garbage on screen.

Fixed a bent pin on ROM 6F. Roms at 6E, 6H, 5E, and 5F were bad. Programmed new ROMs and tested board.

Model: Pac Man
Symptom: Colors wrong on maze

The PROMs at 7F and 4A were for a Pac Man Plus and not a Pac Man. Burned new PROMs and tested board.

Model: Pac Man
Symptom: Maze would disappear and ghosts would all be blue.

This one took awhile to track down. The maze would be there then disappear. Then it would be fuzzily fading out from top to bottom. Very odd symptoms. When the maze disappeared the ghosts would all be dark blue in color and the text describing their names would be the same shade of blue.

Found pin 1 on 5B / 5C, pin 3 & 5 on 5A, and pin 1 on 4D were floating. These pins are tied to +5v through a 1k ohm resistor. Replaced the 74LS194 at location 5C to fix the board. This chip was pulling too much current on pin 1.

Model: Pac Man
Symptom: Sparkling garbage in text and maze

The high speed RAM is used for moving graphics, not the maze. Since the moving characters were perfect the RAM was good. Traced it back to the character EPROM at 5E. EPROM tested good in a programmer but would not run at speed. Replaced the EPROM to fix the game.

Model: Pac Man
Symptom: Garbage on screen.

This was another board that had squished looking blobs for ghosts, text, and fruit as if it were Atari 2600 quality. Very blocky.

Checked the 74LS174 at 1H and it was stuck low. The chip was constanly in clear mode. Checked the circuit and found multple chips hooked to that line, labeled "P" on the schematic. Replaced the 74LS107 IC driving that line and played the game.

Model: Pac Man & Mrs. Pac Man
Tip: Burning new PROMs

When burning PROMs for this game, there are some chips that CAN be successfully substitued.

The 82S126 at 1M and 3M CAN be replaced by an 86S129 PROM.

The 82S126 is Open Collector outputs and the 129 is Tri-State.

I have not tried subbing out the 129 for the 126 at location 4A.

The 82S123 at location 7F is the video output PROM. It CANNOT be replaced by the 82S23. It will technically work but does not have enough current drive and the output is very low resulting in a VERY dim display on the monitor.

Model: Pac Man
Symptom: Dead. Horizontal lines through playfield, but not scores or level/men remaining area.

Replaced 3 ROMS with corroded off legs to fix the dead board problem. The lines looked like a failure in the high speed video memory. Every chip I checked the Data Out line with the logic probe resulted in the signal going nuts on the probe AND on the screen. The well calibrated finger to the bottom of each chip made the screen go nuts. Checked the Data In lines and they were OK. The Data Out connections went from the RAM chips to the 74LS75 IC at location 3D and were tied high by RM2. Touching either of these made the display go nuts.

Checked RM2 (5 pin SIP resistor network. 4 1k resistors with a common to pin 1) which was to tie the DO lines high. There was no connection between each resistor and pin 1. Replaced RM2 with one from a parts board to fix the video.

Model: Galaxian
Symptom: Bad RAM 2 error message on screen

This error message is related to the RAM at 3F or 3H. Replaced both RAM chips then the board came up with a Bad RAM 3 message. This indicates a bad RAM at 4FH or 5FH. Replaced the RAM at 5FH to fix that error. Board then came up with a Bad ROM message. Reseated the ROM daughtercard to fix that error.

Board then came up with horizontal lines across the screen. Burned a new character EPROM at 1H to fix the lines.

Model: Galaxian
Symptom: Bad RAM 1

This indicates a problem with the RAM at 7N or 7P. Replaced both RAM chips to fix the error. The game had horizontal lines across the screen. Replaced the ROMs at 1H and 1K to fix the lines.

Model: Galaga
Symptom: RAM 2L Error

This board was frustrating. RAM 2L bad. Replaced it. RAM 2H bad. Replaced it. RAM 2L bad... RAM 3L bad... RAM 3H bad...

Cleaned the pins on the custom IC at 1H on the video board to fix the error.

Model: Galaga
Symptom: No characters on screen

The player and enemies were both missing. Cleaned the pins on the custom chips on the video board.

Model: Galaga
Symptom: Cannot control Player 1. Enemies go in circles then disappear

This was odd. Game self tested fine and coined up. Player 1 controls were non responsive. Couldn't fire and couldn't move. When enemy ships came down the last one tried to peel away and would go in circles for about 10 seconds then disappear. Once it disappeared the next wave came and the last one repeated the circling and disappearing act.

Checked the ROMs on the CPU board. Found EPROM 3300 was for revision 2 of the Galaga software while the rest of the ROMs were for revision 1. Replaced the EPROM with one holding the correct code to fix the game.

Model: Galaga
Symptom: Random lockups

Board would lock up even during self test. Could tap on the board and cause it to lock up.

Replaced the 3 Z80 CPU sockets. The old TI sockets were making intermittent contact with the chips.

Game: Galaga
Symptom: Locks up after the initialization explosion sounds

The ROMs on this board were Namco instead of Midway with the exception of the ROM at 3M. Replaced it with one programmed with the Namco version of code.

Game: Galaga
Symptom: Faint digital artifacts instead of music.

Resistor pack RM2 was broken. Replaced resistor pack and artifacts were gone. Music was still missing.

The 74LS273 chip at 3B had inputs but no outputs. The clear line was being held high, which is correct. The clock line was cycling during explosions but when high when music was supposed to play. This line is controlled by the PROM at 5C.

Replaced the PROM and the music played as it should.

Read the PROM in the EPROM programmer (7611 which crossed to an 82S129) and it read good. The code didn't change when reading multiple times. Ran the code through ROMIDENT - It's a PAC MAN PROM chip for location 3M. Someone stuffed the wrong PROM on the board.

Model: Galaga
Symptom: Passes RAM tests then instead of explosion sound & crosshatch it dies

Replaced 3 CPU sockets. Board would then get to the point where it says RAM OK then the screen slowly paints white then the board resets.

Checked the EPROMs. Found 2 were for Galaga set 2, 2 were for the fast shoot hack, the ROM at 3J was bad, and the ROM at 3E was for Bosconian!

Replaced the ROMs and the board came right up.

Model: Galaga
Symptom: No sounds except explosions

Sound PROM at 5C was incorrect. It had a PROM for 1D in the socket.

Model: Galaga
Symptom: Reboots constantly

This is different than the bad CPU socket problem in that it wasn't stuck at RAM OK but rather as soon as the crosshatch then the text came on the screen it rebooted. The Reset line on CPU #2 and 3 came active for a VERY short period of time then the game reset.

Swapped out the CPU sockets. Subbed out the custom chips. Nothing. On a whim I turned off each DIP switch and found by playing with them that when DIP switch #3 at 6J was on it would cause the system to lock up when running or to constantly reset when booting.

Replaced the 74LS151 at 4K and the 74LS368 at 5A. Problem still there. Checked the EPROMs again. They were all checking good on the programmer. Swapped out the first 2 program EPROMs. Nothing. On a whim I burned a new set of Williams EPROMs (these were Namco) and swapped out all the EPROM.

Problem fixed.

Model: Galaga
Tip: Replacing PROMs

The PROMs used on the board are Harris 7611. These are 256 x 4 bit bipolar PROMs.

Other PROMs can be used to replace this one, including:

• 5623
• 6301
• 7052
• 74S287
• 82S129
• 93427
• AM27S21
• F93427PC
• 63S141

I have tubes and tubes of Fairchild's 92446 - a 512 x 4 bit bipolar PROM. If you take the code for the 256 x 4 bit PROM and duplicate in the upper half of the PROM these can successfully be substituted for the smaller PROM.

Model: Galaga
Symptom: flickering garbage on screen.

Board had been worked on before by a ham fisted technician. Removed their soldering work at 2K, 2L and 2M. Cleaned up the bridged soldering mess under the socket at 2L, installed new sockets, and installed new chips.

Board now had a solid white screen with garbage characters on the top row. During the attract play when the boss ship captures the player's ship that part is visible on the screen under the garbage but the ray is mixed up.

Pin 19 on 2L was stuck high. The input, on pin 18, was missing because of a damaged platethru. Ran a wire jumper and played the game.

Model: Galaga
Symptom: Multiple graphics problems

Another "attempted repair" by a ham fisted technician. This board had flickering video, incorrect text, bad colors, double characters, and a lot of vertical lines through the screen.

Found a bad trace connecting Pin 1 of 4A. 4A drove address line A9 for 4 of the video RAM chips. Fixed the trace to cure the vertical lines problem.

Found a bad trace connecting pin 1 of 3D. Patched the trace to fix the double characters.

Tapped the board and found that if the EPROM at 4L was tapped the screen flickered and the text changed. Replaced the bad socket to fix the flickering and incorrect text problem.

Repaired a bad trace on the video output resistor ladder to fix the color problem.

Model: Galaga
Symptom: Multiple video problems

Another board from a ham fisted repair attempt.

Board had no video. Cleaned the pins on the custom chips at 00xx, 7xxx, and 02xx. Repaired bad pins on those chips and piggybacked an extra socket on the 00xx and 02xx chips to protect the fragile pins.

Board now has video but the video has blue lines through it. Replaced a broken SIP resistor pack at RM5 to fix the blue lines.

Board now has video but the layout is wrong. Ships are doubled, text and player ships stack vertically up the left side of the screen and the crosshatch has many tiny squares down the left side. Patched a trace between pin 11 of the 00xx and pin 21 of the 07xx chips.

Board now has video but colors are wrong. Replaced all the cut and resoldered resistors in the output ladder. Patched 3 damaged traces. Now the video looks great and I set a new personal high score. ;)

Model: Galaga
Symptom: locks up

2 boards with the same symptoms... Passes RAM/ROM tests, makes the explosion sounds, then locks up randomly. When it freezes up the characters on the screen may or may not disappear. Most of the time the screen will then flip upside down. It might play for a minute or 3 then it will start doing strange things.

Symptoms:

• Starfield starts flickering fast
• Enemies wings move a LOT faster
• Enemies MOVE a lot faster

Tested the ROMs with the EPROM programmer and by substitution. Cleaned the custom chip legs and swapped out the 7xx, 6xx, and 51xx chips. Replaced the ROM sockets and CPU sockets on one of the board sets. The logic probe showed the CPU at 4E was halting. I noticed that when shorting the IRQ pin to D0 (15 to 16) on that CPU the board would run (strangely) and not lock up. Replaced the CPU on each board and played a couple of games.

Model: Pac Man
Symptom: Blocky graphics

Pac Man would coin up and play, but the grapics on the screen were nothing but large squares & blocks.

Replaced EPROMs at 5E and 5F.

Model: Pac Man
Symptom: Flickering garbage graphics. Game will not play blind

The VRAM Addresser (284) module was not in the socket correctly. Removed module and discovered that 2 pins were missing from the bottom. Replaced the socket on the bottom of the module, reinstalled it, and played a few games.

Model: Pac Man 11-in-1
Symptom: Dead. Burned power connector

Replaced the 4 power traces on the connector with copper circuit tape. Board would power up but was dead. The CPU and EPROM board added on as part of the 11-in-1 mod had bent pins on the bottom socket. Replaced the socket and played a few games to test the board.

Model: Pac Man
Symptom: Dead. Burnt edge connector. Black screen.

Repaired the burnt edge connector with copper circuit tape. Powered up the board to find it was dead.

Checked the reset line on the CPU. It was stuck high. Checked pin 9 of IC 9C and found the reset switch was working properly. The IC at 9C was not receiving the VBLANK signal on pin 2. Traced this back to the 74LS74 at 5M. Found the 16V, 32V, 64V and 128V clocks were missing. Further troubleshooting revealed that all of the V clock signals were missing.

Checked the IC at 3N and found the 16H and 64H signals were present on pins 11 and 12. Replaced the IC, no change. If pins 11 and 12 are shorted together, the game will boot but will have the screen divided into 9 identical small screens. checked the 74LS161 ICs at 3R and 3S. The IC at 3R had identical outputs on pins 11, 12, and 13 instead of divided clock signals. Replaced the IC at 3R and played a few games to test.

Model: Ms. Pac Man
Symptom: Dead. Had shipping damage due to insufficient packing and no zip ties on daughtboards.

Board arrived with shipping damage. Once damage was fixed, the board was still dead.

The VRAM Addresser and Z80 Sync Bus Controller modules were both floating around loose in the box. They weren't zip tied into place.

Removed the bent up socket on the bottom of the VRAM Addresser board and replaced it. Straightened the pins on the Z80 Sync Bus Controller board. Board symptoms: Dead.

Replaced bad CPU. Game would play but had no audio. Used the logic probe and found audio signals at the output of the sound section. Used the oscilloscope and verified audio was getting to the final amplifier IC's input pins. Replaced the bad audio amplifier IC and the filter cap on the 12v line.

It's uncommon to have a blown audio amplifier IC. If a Pac Man series or Galaxian series board is put into a Neo Geo multislot cabinet with a JAMMA adapter, the audio IC will get finger blistering hot and burn out. The multislot MVS boards are wired differently and this stresses the audio output IC.

Model: Galaxian
Symptom: Constant background tone when playing

Galaxian is supposed to have a varying tone in the background when playing. It gets faster and faster as the game is played. On this board it was only playing a single continuous tone.

The troubleshooting guide points to a problem with a 555 timer and the 2 GE6015 transistors. The 555 timer had already been replaced by the customer. Checked the 2 GE6015 transistors and they were good.

Checked C15, C16, R15, R16, R17, R18, R20, and R21. All checked good. Swapped the 555 timer chip since it was CMOS and the original part wasn't. No change. Checked the resistance from pins 2/6/7 of the 555 to +5v and ground. It read 1200 ohms to both power and ground. Swapped out the LM324 quad op-amp chip to repair the board. It connected to pins 2/6/7 of the 555 timer chip and had an internal short to power and ground on the input.

Model: Galaxian
Tip: Transistor cross reference

The Galaxian sound subsystem uses 2 GE6015 transistors to oscillate the background audio. These transistors are no longer made and are not in the NTE cross reference book.

They can be successfully replaced with the easy to find 2N3906 transistors.

Model: Mortal Kombat 4
Symptom: Board had multple RAM failures and no video sync

Replaced U74, a surface mount 74LS07 and replaced a burnt zero ohm resistor on the video ground to fix the video sync problem.

Resoldered U66, U32, U62, and U63 then resocketed U48 to fix the RAM issues and random reboot issues. Board can now be jostled briskly without rebooting.

Reset button was dead. It had liquid (rodent?) damage. Cleaned the board and replaced the switch.

Model: Pac Man Jr.
Symptom: Burnt edge connector.

Repaired connector traces with copper trace tape and tested.

Model: Galaga
Symptom: Dead. Stuck in reboot loop.

Removed a 68B09 CPU from socket 4H and installed the proper 51xx custom Namco chip. Replaced the 3 Z80 CPU sockets and the 6 ROM sockets. Board would still either be stuck in a reboot loop or act dead. When it acted dead the CPU was stuck in a reset loop. If the board was slightly flexed it would try to boot.

Replaced a bad socket on the 7xx chip. The VBLANK* signal was not getting to IC6A, pin 1, to keep the watchdog signal from resetting the CPU. Reset the DIP switches to factory settings and tested.

The board was now missing all text on the screen except the very top row, which was green instead of red. When playing game the flags showing the level were the wrong color and missing lines and the line showing the credits was missing.

This is handled by the EPROM at location 4L. It is fed by a 74LS273 at location 2L and 74LS86 at location 2N. These were good, the EPROM tested good by a programmer and by substitution. All the signals were correct on the custom chip at location 4H. The IC at 4H outputs the control signals for those images out pins 11 and 12 to pins 5 and 6 on IC 2N, a PROM. Checked the PROM and found that pin 9 was folded under the chip. This is the D3 output. Straightened the pin and tested the game.

Model: Galaga
Tip: Stuck in reboot

If the DIP switch for Video Freeze (6J, switch 5) is left on and the game restarted it will be stuck in a reboot loop until the switch is turned OFF. The effect is different than when you have bad CPU or ROM sockets on the CPU board where it shows RAM OK then reboots. In this case, it is showing ROM OK, RAM OK, and the rest of the normal text before suddenly rebooting.

If after replacing those CPU and ROM sockets (which should be done on ANY Galaga game that still have factory sockets) the board is still rebooting then check that switch. You'll save yourself headaches.

Model: Galaga
Symptom: Multiple problems. Board had been worked on before.

Board would boot but had no explosion sounds and would not accept inputs properly. Sprite graphics were missing every other vertical line and there were vertical blue noise 'tails' on the bottom of the screen.

CPU board: Replaced missing 00xx and 06xx ICs. They were in the box with the board but were not installed and had missing pins. Repaired broken pin 28 on custom IC 55xx to fix the input and sound problem.

Video board: The sprite problem would come & go with flexing the PC board. Replaced a bad socket and trace on pin 3 of 1C. Resoldered the SRAM socket on 2148 SRAM at 6B. The ground pin was not soldered properly. Resistory pack RM7 was bad and causing the blue vertical streaks.

Model: Galaga
Sympom: Dead. No video output.

Board was previously worked on and had problems on both the CPU board and Video board.

CPU board: Fixed one badly jumpered trace. Replaced a bad EPROM at 3K, the D1 and D2 lines were shorted internally. Replaced bad sockets on the CPU at 4M and the Namco custom chips at 4D, 2L, 2J, 2H, and 2E.

Video board: Cleaned board. The 6MHz clock signal was not getting to pin 1 on the 02XX IC at location 4H. Replaced bad sockets on Namco custom chips at 1N, 1L, 1H, and 4H. Fixed a broken leg on the 07XX chip at 1N and cleaned the legs on the custom ICs at 1N, 1L, 1H, and 4H. Cleaned the legs on the SRAM IC at 1K to finish the repair.

Model: Ms. Pac Man
Symptom: Dead

Removed the daughterboard and powered up the system without it to isolate problems. Some of the normal startup RAM tests are occurring but when it is supposed to switch to another area of RAM it reboots. Rebooting is NOT being kicked off by the watchdog timer.

Found that when the board was flexed it would boot normally. Found a cut on the trace coming from pin 3 of the 74LS367 buffer chip at 6R. This was the AB10 signal line feeding the 74LS139 2 to 4 selector that controlled the CS* (Chip Select) line on the 2114 SRAM ICs. Repaired the trace and the board would play as a Pac Man game with corrupt characters, normal since the Ms. Pac Man ROMs were in 5E/5F.

Replaced a broken 40 pin connector on the daughter board ribbon cable, reassembled the game and tested.

Model: Galaxian
Symptom: No Sync

Replaced a bad 74LS08 at location 6H and tested.

Model: Pac Man
Symptom: Dead

Board had attempted repairs already done.

There were a few pins on the machine pin sockets from the attempted repairs that weren't fully soldered in. Once that was done the symptoms looked like bad RAM. If the board was flexed it would give different bad RAM symptoms - All zeros, colored text/graphics, and even booted once.

Broke out the pscilloscope on this one... the upper data bits were horribly garbled. Replaced the 6 2114 SRAM sockets and tested. Board died during extended testing. The Reset* line died. Without the proper reset pulse at power on the Z80A CPU will never start.

Replaced a 74LS161 at location 9C to fix the reset circuit.

Model: Cruis'n USA
Symptom: Dead

Board was paired with a Cruis'n World and someone tried to troubleshoot by swapping parts.

Sorted out the ROMs with an EPROM programmer and eplaced 1 missing program ROM. Swapped the correct PALs back on the board and tested the game.

Model: Pac Man
Symptom: Garbled sound.

This board had been worked on before. There were many patches on this board and the IC at 1N had many traces and pads pulled. It also had many of its holes DRILLED out.

Removed a short between pin 5 and 11 on the 7489 RAM at 2L to fix a portion of the sound.

Removed short between pin 8 of 1N and R4. Patched open trace between pin 9 of 1N and R4. Now the sound disappeared. This was because one of the inputs on the digital switch was shorted directly to the resistor on the output.

Patched open trace between pin 7 of 1N and ground. Noticed that 1N was incorrect. Replaced the 4006 at 1N with a proper 4066 IC and redid many patches on the board then played a few games to test the board.

Model: Galaga
Symtpom: No sound and graphics problems

Installed a renew kit (new 24/28/40/42 pin sockets... resistor packs did not need replacing), cleaned all chip legs, and reinstalled the chips into their new sockets. Tested game. Game now works, with sound, but has a strange graphic anomaly: The player and enemy ships are all tilted to 45 degrees, player explosions are divided into four pieces, and enemy explosions are numbers 20 over 31. If the enemies are tilted to the left the numbers are upside down and if they are tilted to the right the numbers are right side up.

Checked the Graphics ROMs on the video board. Pins 1 and 2 were stuck low with very rapid racing pulses. Checked the 74LS153 at 1B and found it had normal inputs but bad outputs. Replaced the IC and tested the game.

Model: Galaga
Symptom: Missing some blue on motion graphics and random blue streaks on board

This was a very tough one to track down. The board worked fine until an extended burn-in was done. Swapped out the motion RAM (8 x 2147), the resistor packs that hold the data lines high, 1 PAL, and a couple other 74xx chips. Replaced the 74LS298 at location 5B to fix the missing blue. This chip multiplexes the 8 data output lines from the motion RAM into 4 for mixing with the text graphics and later with the starfield.

The random blue streaks was just as tough to track down. Checked the 74LS365 chips at 5A and 6A, swapped out 2 of the replacement Video RAM chips, and checked the 74LS157 at 4A. (Yes, 4A. It says 5A on the schematic, but there's a 74LS365 at that board location. The schematic has an error.) Traced the problem back to pin 10 on the 74LS20 at location 3A which feeds the LS157. Pin 10 is the 6MHz* clock. Swapped the 07xx IC to no change. Replaced the 74LS368 IC at location 3N to finish the repair.

Model: Ms Pac Man
Symptom: Hacked and missing parts

Board was missing the Z80 Sync Bus Controller and Z80 CPU. Replaced missing parts and the board worked, but had an odd problem with the text on the top and bottom lines of the screen.

The text was cut down the middle and repeated on the right side of the screen. "1UP   HIGH" was repeated on the left side and right side of the screen. The remaining text for HIGH SCORE and 2UP was missing. Same thing with "CREDIT 0" on the bottom.

Pin 4 of the middle 74LS157 was supposed to connect to pin 2 of the middle 74LS257 on both sides of the connector that plugs into the main board. Removed a blob of solder that was an attempted repair and soldered in a jumper to finish the repair.

Model: Pac Man
Symptom: Random reboots

Cleaned the Z80 Sync Bus controller chip's pins. This was the old custom chip version with tarnished legs, and not the daughterboard. Replaced the bad CPU socket and ROM 5E sockets to finish the repair.

Model: Pac Man
Symptom: Dead hacked board.

Board was poorly hacked and had jumper wires that were not soldered on one end.

Removed the 8 EPROMs for the Ms Pac Man bootleg hack, removed several jumper wires, fixed 5 cut traces, and installed freshly programmed Pac Man ROMs in rows 5 and 6. Tested game.

Model: Ms Pac Man
Symptom: Garbage on screen

Board was reported as dead with garbage on screen, but booted fine on the bench. If the ribbon cable to the daughter board was bumped, the board would reset. Replaced bad 40 pin socket on the daughter board and tested.

Model: Ms Pac Man
Symptom: Dead: Garbage on screen, random audio tones

Board had a hacked ribbon cable that had at one time burned a wire. Also, a chip on the Z80 Sync Bus Controller had been replaced.

Checked the daughter boards. The VRAM Addresser had a bent pin 13. Straightened pin and reinserted the module. Checked the Z80 Sync Bus Controller and found that pin 14 had burned. Cleaned pin 14 and replaced both the Sync Bus Controller socket and the CPU socket.

The game would now run, but the moving characters were doubled - all the ghosts were blobs with 4 eyes and Ms Pac was made with 2 upper halves. Replaced 2 noisy 74161 and 1 noisy 74LS10 that had garbled signals on some pins. This cleaned up the signals, but didn't fix the issue. Replaced a bad 74LS157 driving the Character ROM address lines to finish the repair.

Model: Galaga
Symptoms: Graphics corruption

Replaced every tall, flat style resistor pack and tested. These packs are sources of a lot of problems on Galaga boards.

Model: Galaga
Symptom: Dead. Garbage on screen.

Installed all new 24/28/40/42 pin sockets. Cleaned the custom chips. Board would run but would die when hot. Replaced CPU at 4M to finish the repair.

Model: Ms. Pac Man
Symptom: Constant reboot. Trash on screen

Board would go through the normal boot cycle but would reboot before it would finish. There were random vertical lines on the screen. Replaced bad 74LS245 at 4H. Board would still reboot, but garbage was gone. A close look showed an error message flashing just before reboot. Replaced bad 2114 at 4P to finish the repair.

Model: Galaga
Symptom: No coin inputs and faint garbage lines on screen during self test

Replaced bad resistor pack at location RM10 to fix coin inputs. Replaced EPROM sockets and 42 pin socket on the CPU board. Replaced all 24/28 pin sockets on the video board. Tested. Replaced bad PROM at location 2N to fix the faint line issue and retested board.

Model: Galaga
Symptom: RAM 0L error

Replaced all resistor packs and 24/28 pin sockets on the video board. Cleaned legs on the custom chips. Board then fired up with a 2L error and random garbage on screen. Garbage would change when pins 1-7 were checked on the SRAM with a logic probe. Replaced bad 04XX chip and tested. Replaced all 24/28/40/42 pin sockets and all of the resistor packs on the CPU board. Tested.

Model: Pac Man
Symptom: Dead

Board was part of a group of 7 boards sent in for repair. It would not try to boot and was stuck in watch dog. Replaced CPU socket then board would try to boot but fail. Checked the ROMs and found Pac Man Plus ROMs on the board. Reprogrammed the 4 program ROMs and 2 character ROMs and tested. Board had Pac Man PROMs so the colors were OK.

Model: Pac Man
Symptom: Dead

Board was part of a group of 7 boards sent in for repair. It would not try to boot and was stuck in watch dog. Checked the ROMs and found a rotted pin on 6E and a mixed set of bootleg ROMs for the remaining 3 on row 6. Replaced the bad ROM and reprogrammed the other 3 program ROMs and tested. Board had a Pac Man Plus PROMs at 7E which caused the board to output incorrect colors. Replaced the PROM and tested.

Model: Ms Pac Man (boot)
Symptom: Dead

It was an original Pac Man board, but hacked with 2 extra ROMs to run as Ms. Pac Man. Board would boot, but was stuck in reset with nothing showing on screen. Four of the 8 data lines were dead on the Z80 Sync Bus Controller. Replaced bad (non-original) socket on the Z80 Sync Bus Controller. Board would boot to text garbage on screen. Fixed 1 broken trace between the Z80 Sync Bus Controller and the CPU. Board would then boot, get to the Memory OK screen, then reboot continuously. Repaired a broken trace for A11 between ROM 6J and 6K. Board then booted and ran, but the background maze would randomly disappear. Cleaned the pins on the ROM at 5E to finish the repair.

Model: Ms Pac Man (boot)
Symptom: No sound. Graphics issues.

It was an original Pac Man board, but hacked/converted with 2 extra ROMs to run as Ms. Pac Man. Board had no sound and displayed flashing garbage for the pink ghost. Also the pink ghost was 1/4" lower than the other ghosts. Replaced a bad RAM at 3F to fix the graphic corruption. The display looked normal but the ghosts were moving in a jerking manner and the display would disappear after a minute of being on. Replaced a bad RAM at 3H to fix the movement of the ghosts and replaced a bad 74LS157 at 5A to fix the disappearing display. Replaced a bad 74LS273 at 2M and the sound was partially restored. Instead of no sound, it made popping noises where sounds were supposed to be. Replaced a bad PROM at 3M to finish the sound repair. Repaired a burnt edge connector and tested the game. Found horizontal lines through ghosts & Ms. Pac Man. Replaced bad socket at 5F and re-tested.

Model: Ms Pac Man
Symptom: Dead

Board had some shipping damage and when on the bench was not stuck in watchdog. Straightened many bent pins on the Z80 Sync Bus Controller Module and the VRAM Addresser Module. Checked the 74LS161 chips at 2R/2S and 3R/3S. The chips at 2R/2S had no outputs. Replacing 2R/2S had no effect. Replaced 2P to no effect. Replacing the 74LS74 at 5M fixed the game. The outputs on 5M were there, but incorrect, causing the 74LS161 chips to not work. Installed missing zip ties to hold the 2 modules in place before returning to customer.

Model: Ms. Pac Man
Symptom: Dead - garbage on screen

Board had a strange hack with a 74LS257 on it. The wires for the 257 were not all attached to the board. Removed the hack, cleaned the insides of the legs on the mask ROMs and fixed 2 bent pins on the VRAM Addresser module. Fixed 6 burnt power supply fingers on the edge connector and installed an edge connector trace for the missing player 1 start connection. Replaced missing zip ties on the 2 daughter cards and tested board.

Model: Galaga
Symptom: White screen. Dead.

Board had been worked on before. Installed a renew kit (new 24/28/40/42 pin sockets & all resistor packs) on the CPU board and found that 2 of the 08xx chips on the CPU board had pins bent under them. Repaired the pins as they will snap off when straightened, cleaned all the custom chips and tested. Game now worked but had no starfield and had blue lines on the screen.

Installed the renew kit on the video board, replaced the starfield generator, cleaned the pins on the custom chips and tested. Replaced the 2147 at 6L to fix the blue line issue and re-tested board.

Model: NFL Blitz 99
Symptom: Dead Short

Replaced 2 shorted tantalum capacitors on the -5v line and tested.

Model: NFL Blitz 99
Symptom: Will not work in Standard Res mode

Tested the DIP switches and found that U8 Switch 2 was stuck open. Replaced the surface mount DIP switch with one from a parts board and tested.

Model: NFL Blitz 99
Symptom: Buzzing sounds from speakers, won't enter test mode

Board was VERY dirty. Cleaned board and replaced both sets of DIP switches. Audio issue was very odd. The hard drive, video, and any other operation could be heard through the speakers. The noise could be seen as ripple on the +5, -5, and +12v lines and No audio from the game was present. Pulled the D/A converter with no change. Pulled the audio op-amp and noise disappeared. Replaced the op-amp and reinstalled the D/A converter then tested.

The bad op-amp was overdriving the audio output IC and causing the loud noise. The overdriving also caused large current pull from the power supply which showed as ripple on the outputs and as noise through the speakers.

Model: Galaxian
Symptom: Distorted characters/text and text wrapping around right side of screen

All address and data lines were present but not proper on the character ROMs. Shorting A1/A2 together made the garbled blocks look more like text. Checked the 74LS273 at location 2M and found output pin 9 was dead and pin 6 was strobing. Replaced the IC and tested the game.

Model: Pac Man
Symptom: high pitched beeps and blips instead of normal sounds

The beeps and blips occurred at the same time and cadence as the normal sounds. Replaced the 74LS273 and checked the PROMs by both checksum and substitution. Replaced the 2 bi-polar RAMs. No change. Compared signals to a working board and found all the enable lines were correct. Replaced the 74LS283 at 1K to fix.

Model: Galaga
Symptom: Reboots, crashes

Installed renew kit and replaced 1 cracked 1K resistor. Tested.

Model: Galaxian
Symptom: Dead. Garbage on screen.

Reseated the ROMs. Address lines were stuck high. Data lines were dead. CPU stuck in watchdog reset. Replaced bad Z80 CPU and tested.

Model: Ms Pac Man
Symptom: Dead. Garbage on screen.

Reseated the Z80 Sync Bus Controller. It was in the socket incorrectly and off by 1 set of pins. Audio had a repetitive whump whump whump type sound like a helicopter. Replaced C51, a 330uf @ 16v cap to fix the audio. Tested game.

Model: Mortal Kombat II
Symptom: Garbage on screen

Board failed video RAM tests. Reseated UB21, replaced bad battery holder, and tested.

Model: Mortal Kombat II
Symptom: Game will not start

Board passes self tests and coins up. When P1 or P2 start button is pressed the game immediately shows "game over" on screen. Reflowed surface mount memory access controller chip at UE13 and tested board.

Model: Ms Pac Man
Symptom: Dead. Garbage on screen.

Board was stuck in reset. Replaced bad 74LS74 at 5M. Board now had garbage on screen and intermittent reset. Cleaned the legs on the program ROMs and replaced the ROM at 6J as it had 2 broken legs. Board then had multiple vertical images and would not reset consistently. Replaced bad 74LS161 at locations 2S and 3S. Board played but would reset when jostled. Replaced the socket on the daughter board and both ends of the ribbon cable to finish the repair. Tested board.

Model: Ms Pac Man
Symptom: Stuck in loop

Board was stuck trying to boot. It would occasionally flash the number "1" on the screen. Replaced the SRAM at 4R. Board then would try to go through self tests and would reboot half way through them. Replaced the SRAM IC at 4L. Tested game.

Model: Ms Pac Man
Symptom: Dead. Garbage on screen.

When the daughter board was removed and the Z80 placed on the main board, the game played as Pac Man with a garbled Ms. Pac. (which is normal!) Checked the ROMs on the daughter board and replaced both U5 and U7. Tested.

Model: Galaxian
Symptom: Dead

Board had damage from a previous attempted repair.

Board would try to boot but just make beep/blip noises and repeating garbage on the screen. Cleaned the legs on all the ROMs. ROM W on the daughter board had a broken leg. Patched the bad leg and replaced a bad ROM U on the daughter board. Chip at 9B had a pulled trace that needed patching. Patched the trace then replaced a bad 74LS367 chip at 8D. Board would THEN try to boot but had a RAM Error. Replaced a bad RAM chip at 5F. Board then booted but had color stripes on the screen and no stars. Replaced bad ROM at 1H to finish. Tested game.

Model: Ms Pac Man
Symptom: Garbage on screen. Plays

Board had flickering garbage on screen but played normally. Isolated problem to the VRAM Addresser. Pins were good. Removed a wire shorting 2 pins from the top of the board and replaced a bad 74LS257 IC to finish the repair.

Model: Ms Pac Man
Symptom: Dead. Garbage on screen.

Board had physical damage to the ribbon cable. Removed Z80 CPU from the daughter board and installed it on the main board. Game played but with the expected graphic issues. Assembled a new ribbon cable, installed it, and tested the game.

Model: Pac Man
Symptom: Characters only move around bottom right quarter of the screen

Board had a 6-Pac mod installed.

Cleaned the edge connector and reinstalled the 6-Pac ROM card to fix rebooting issue. Replaced bipolar RAM at 3F to fix character issue. Tested.

Model: Ms Pac Man
Symptom: Dead

Board had a short on the +5v line and an attempted repair had been made.

Replaced the regulator current pass transistor/heatsink assembly to fix short. Replaced the CPU, CPU socket, 1 ROM socket, and the ribbon cable. Tested board.

Model: Ms Pac Man
Symptom: Dead

Jumpered 6 bad traces on a previously replaced socket and replaced the ribbon cable. Tested.

Model: Pac Man
Symptom: Garbled video

Board was modified with the 4-in-1 game single ROM mod and an NVRAM adapter for saving high scores.

The NVRAM adapter doesn't fit well with ceramic cased RAM chips under it. Stacked 18 pin sockets under the adapter and tested.

Model: Ms Pac Man
Symptom: Dead

Board would not boot. Voltage was sitting at 4.17 volts and the board started smelling hot. Removed the backwards installed Z80 Sync Bus Controller module and board would then come up at proper 5.0 volts. Replaced all 8 TTL ICs on the module, reinstalled it, and tested the game. Replaced the missing zip ties to hold the modules in place and replaced burnt traces on the edge connector with copper trace tape. Retested game.

Model: Ms Pac Man
Symptom: 4 small screens of garbage on monitor

Replaced bad 74LS161 at location 3R. Tested.

Model: Bosconian
Symptom: White screen

Replaced all of the 24/28/40/42 pin sockets on the board. Replaced bad PROM on the video board to fix white screen issue. Board worked but had intermittent graphics issues and no music. Replaced a PROM on the CPU board to fix music issue. Replaced 3 bad 74LS367 chips buffering the CPU board to the video board and 1 74LS138 on the CPU board which fixed the intermittent graphics issue but then the board had issues with text showing up as multicolored and with every other column being flipped. Replaced 3 more 74LS367 chips buffering the CPU board to the video board.

Each one of the bad LS367 were Fujitsu brand and had broken die connections as the graphic corruption symptoms would come and go if the chips were tapped. Replaced the remaining 2 Fujitsu 74LS367 chips for good measure and did a final test on the board.

Model: Pac Man
Symptom: Graphic Corruption on maze. Sparkles on screen during attract mode.

Replaced bad character ROM at location 5E and tested.

Model: Pac Man
Symptom: Nothing on screen

Board would occasionally flash "Memory OK" on the screen but other wise was blank.

Replaced 2 bad program ROMs and tested.

Model: Galaga
Symptom: Dead. Nothing on screen

Board had been previously worked on. All but one of the 24/28/40/42 pin sockets were replaced. Checked for bad solder joints and shorted solder joints. Found none.

Game had no clock signals. Crystal was oscillating but the clock was missing. Replaced bad 74LS368 at 5a. Clock signal was now making it to the divider but not out. Replaced bad 74107 at 5B. Board would power up but not run. If the board was reset manually it would boot and work. Replaced C44 and the power on reset circut was now working. Board would run but had no music. Replaced bad PROM at 1D. Tested. Replaced the socket on 6M to finish replacing all the sockets on the board. Installed all new resistor packs to replace the old ones that go intermittent and retested.

Model: Galaga
Symptom: Dead. Garbage on screen.

Board had been previously worked on. New 24/28 pin sockets and resistor packs had been installed.

CPU board tested good by substitution. Board was not attempting to boot at all. Checked the 2k x 8bit SRAM IC, the main CPU's memory, for missing signals. Jumpered a bad trace going to pin 1 from a replaced resistor pack. Tested.

Model: Galaga
Symptom: No music or sound effects

The explosion sounds worked. Checked the digital parts of the sound circuitry and found that the /DO1 through 4 lines on the 7489 at 2A were stuck high. Replaced the bipolar RAM chip and tested.

Model: Pac Man
Symptom: Game plays but has flickering garbage through screen.

Pin 15 was broken off the VRAM Addresser module. Replaced the adapter socket on the bottom of the module and tested.

Model: Pac Man (96-in-1 kit installed)
Symptom: Dead

96-in-1 kit was tested by the seller of the kit and sent back to the board owner with a new ribbon cable, but board would still not work.

Checked the 2114 RAM chips and both daughter boards. Did a check of the bottom of the board for trace damage and found a solder smear between pin 3 of 6S and two traces next to it. Used liquid flux and a hot iron to remove the short. Tested board.

Model: Ms Pac Man
Symptom: Dead

Board had attempted repair damage.

Board was stuck in reset. Replaced bad IC at 5M to fix reset problem. Replaced the 4 factory PROMs with broken legs with 4 programmed EPROMs. Fixed a broken pin on the Z80 Sync Bus Controller module. Tested.

Model: Ms Pac Man
Symptom: Dead

Board had attempted repair damage.

Replaced the 4 factory PROMs with broken pins with 4 programmed EPROMs. Replaced 8 bad 2114 DRAMs and their sockets. Tested.

Model: Pac Man Plus
Symptom: Dead

Board had attempted repair damage.

Repaired gouged trace. The CPU module was bad. Installed a Z80 CPU, 4 program EPROMs, 2 character EPROMs, Color PROM, Video Output PROM, and a Ms Pac Man daughter board to convert game to Ms Pac Man at customer's request.

Model: NBA Hangtime
Symptom: RAM Errors

Board had physical damage. Straightened bent pins on U32 and removed 2 solder smears from the bottom of the board to fix RAM errors. Reprogrammed U112 to fix a ROM error. Tested.

Model: Ultimate Mortal Kombat 3
Symptom: RAM Errors

Board had physical damage.

Replaced a bent pin on the PLCC socket for U45. Tested board. Reprogrammed U3, U113, and U132 to fix ROM errors. Tested board.

Model: Galaga
Symptom: Parts board rebuild

Board had been worked on before and put into a box of parts boards by another tech. Two of the customs on the video board were in wrong sockets, one ROM was in the wrong socket, and the 06XX and 16K SRAM chips were missing.

Installed renew kit - all new sockets & resistor packs. Cleaned custom chip legs. Installed missing ICs. Repaired pins on the 02XX and the 07XX chips on the video board. Board would boot but would fail randomly on start up on different RAM chips. Replaced a bad 74LS138 at 1E on the video board to fix a random memory error on boot. Tested board.

Model: Galaga
Symptom: Parts board rebuild

Board had been worked on before and put into a box of parts boards by another tech. Four resistor packs were replaced with the wrong type and a 5th had been replaced with the bad, flat style of resistor pack that should not be used on these boards.

Installed renew kit - all new sockets & replaced all old style resistor packs. Cleaned custom chip legs. Repaired pins on 2x 08XX, 51XX, and the 54XX chips on the CPU board. Board would boot but would fail with a 4L RAM error. Replaced a bad 08XX IC on the CPU board and tested.

Model: Galaga
Symptom: Parts board rebuild

Board had been worked on before and put into a box of parts boards by another tech. Three caps had been replaced incorrectly.

Installed renew kit - all new sockets & replaced all old style resistor packs. Cleaned custom chip legs. Repaired 2 pins on one 08XX IC and replaced 3 incorrect caps - 2 radial and 1 axial that was physically too big. Removed tape from the edge connector and cleaned the residue. Tested board

Model: Mortal Kombat 4, Revision 2
Symptom: Burnt components next to JAMMA edge conector

Replaced a bad 0 ohm surface mount resistor in the Video Ground circuit. Replaced a bad surface mount cap in the Sync Output and Blue Output circuits. Replaced a bad 33 ohm resistor in the Blue Output circuit. Board powered up but had no sync. Replaced a bad surface mount 7407 IC in the Sync Output circuit and tested the board.

Model: Mortal Kombat III
Symptom: Dead

Jumpered 1 burnt trace where a coil used to be. Replaced a surface mount coil at L54 in the power circuit for a 74ABT244. Reflowed the DMA Controller at U33 and the Orbit chip at U32. Board booted with WWF instead of MKIII. Replaced all ROMs and the security chip. Tested. Board had graphics corruption. Replaced chip at U45 and retested.

Model: MKII
Symptom: Reboots at random

Reflowed the surface mount DMA Controller IC. Tested.

Model: WWF Wrestlemania
Symptom: Random reboots and garbage on screen

Reflowed the DMA Controller IC and fixed bent pins on a custom PLCC. Replaced bad U125. Cleaned battery contacts and tested.

Model: UMK3
Symptom: Lines under players. Fails self tests showing all Graphics ROMs bad.

Resoldered the CPU and 3 RAMs to fix lines under player issue. Address lines A0-A6 on the Graphics ROMs were not being actrivated during self test. Replaced a bad 74F373 and tested.

Model: Mortal Kombat 4
Symptom: No video sync

Replaced a dead SMT 74LS07 and a fried zero ohm SMT resistor in the video ground circuit. Tested.

Model: Mortal Kombat 4
Symptom: No video output

Replaced 3 fried 33 ohm SMT resistors to fix the video output. Replaced a dead SMT 74LS07, a 1K SMT resistor, and a fried zero ohm SMT resistor in the video ground circuit to fix the sync issue. Tested.

Model: NBA Max Hangtime
Symptom: Missing U36. No sound in game. 10 bongs during self test.

Replaced missing U36. Board would then boot but showed a ROM error. Reprogrammed U132 ROM. Board would boot but fail sound tests with 10 bongs. Replaced cracked SMT coil in the sound circuit. Tested.

Model: WWF Wrestlemania
Symptom: Bad U14 during self tests

Replaced IC U14. Tested.

Model: Ms Pac Man
Symptom: Dead

Cleaned the tarnished legs on 3 mask ROMs and corroded legs on 1 EPROM. Tested

Model: Ms Pac Man
Symptom: Dead. Missing ribbon cable.

Board was part of a bulk buy and had a bootleg Ms Pac daughter board and no ROMs on row 6. Board was also poorly converted to run on DC power.

Removed several jumper wires and repaired a burnt pin on the edge connector. Installed ribbon cable and tested. Fixed broken pin on the sync buss controller chip. Board would still not boot. Replaced bad CPU and successfully tested.

Installed ROMs on row 6 and replaced the bootleg daughter board with an original. Since the bootleg board required no ROMs on row 6, kept that board as a troubleshooting tool for fixing Pac/Ms Pac/Pac Plus boardsets to quickly rule out ROM issues.

Model: Ms Pac Man
Symptom: Dead

Board would boot if tapped "just right". Replaced sockets on the 74LS259 at 8K, the CPU, and the Z80 Sync Buss Controller. Board booted and worked, but had very thin horizontal lines bridging some text. Replaced the PROM at 4A and tested.

Replaced a bad 2200uf cap and an incorrect 330uf cap where someone used a radial instead of axial. Tested.

Model: Pac Man
Symptom: Dead

Fixed bent pin 20 on CPU, replaced bad socket on Z80 Sync Buss Controller, and patched one bad trace. Tested.

Model: Pac Man
Symptom: Dead

Replaced bad socket on Z80 Sync Buss Controller and replaced the Ms Pac ROMs on row 5 with Pac Man ROMs. Tested.

Model: Ms Pac Man
Symptom: Dead

Replaced bad socket on ROM at 6E and the socket for the Z80 Sync Buss Controller. Replaced missing socket on the pins of the Z80 Sync Buss Controller card. Board would boot but had glitches in background graphics and missing characters. Replaced bad socket on the ROM at 5F to fix glitching and replaced a bad 74LS20 at 3E to fix the missing characters. Tested.

Model: Pac Man
Symptom: Dead

Replaced bad CPU, ROM 6E, and fixed a broken pin on the EPROM in 6J. Jumpered a cut trace on 8C pin 11 to undo a mod someone had performed on the board. Replaced bad Mask ROMs at 5E and 5F. Board played but had horizontal lines across screen. Replaced bad RAM at 1C and tested. Repaired burnt edge connector and restested.

Model: Pac Man
Symptom: Dead

CPU was dead. Checked /RESET and it was missing. Replaced bad 74LS161 at 9C. Board would try to boot but fail and the data bus would lock. Replaced bad 74LS245 at 4H. Tested.

Model: Galaga
Symptom: Dead

Board had attempted repair damage. Board was part of a pile of parts boards to be resurrected and had already had the 40, 42, and 28 pin sockets replaced on the CPU board.

Cleaned the excess solder from the edge connector. The audio amp chip had severe heat damage. Replaced 4 incorrect radial capacitors with proper axial types. Removed solder short from the only correct axial type installed (C20) that grounded out the output of the audio amp chip. Removed the heat damaged audio amp chip, rebuilt missing ground trace with copper foil tape, installed replacement amp, and jumpered 2 missing signal traces to it.

Removed solder shorts from the 06xx and one of the 08xx chips. Boardset was still dead. Examined the custom ICs on the CPU board and discovered the 06xx was missing the ground pin. Replaced the damaged socket on the 06xx and attached a pin from a donor chip. Tested. Boardset still had no video but would now play blind.

Examined the video board. The 05XX chip had 5 broken pins. Replaced the old style resistor packs on the video board and replaced all the 24/28 pin sockets. Cleaned the legs on the customs. Replaced a wire patch on the 07XX chip with a leg from a donor chip. Repaired the 5 damaged pins on the 05XX custom chip with legs off a donor chip. Tested board.

NOTE: The PROM at 5N outputs the video. The enable line (pin 15) for it is controlled by the 05XX. The missing power pin caused the 05XX to be dead and not enable video output.

Model: Ms Pac Man
Symptom: Dead

Cleaned corroded pins on U6/U7 ROMs and replaced the ribbon cable socket on the daughter board. Game would try to boot and crash. Replaced the Z80 Sync Buss controller and the VRAM Addresser sockets. Board booted but immediately started a game and move to the left. The screen would shift colors to all white and the eyes for the ghosts would not line up with the character sprites. Noticed that if the data bus pins were probed with the logic probe that Ms Pac would move on the screen according to the DB pin that was probed corresponding to the 74LS367 outputs for the control inputs, but the controls themselves were non-responsive.

Replaced 74LS138 at 7J to fix input problem. It wasn't toggling the /IN0 and /IN1 enable lines on the 74LS367 chips buffering the inputs. Replaced the PROM at 4A to fix the colors shifting. Replaced the color RAM at 2A to fix the problems with the eyes on the ghosts and horizontal lines on the screen.

Repaired a burnt trace on the edge connector, replaced a physically damaged resistor at R5, and retested.

Model: Ms Pac Man
Symptom: Dead

Replaced 4 corroded ROMs and sockets on row 6. Board had scrolling garbage on screen. Replaced bad 74LS161 chips at 2S, 3R, 1E and 2E. Replaced bad CPU and ribbon cable. Board booted but had no sound. Replaced sound PROM at 1M and tested.

Model: Ms Pac Man
Symptom: No characters on screen. No sound.

Board had been modified for a single ROM hack.

Characters were missing on screen. Chips in the motion RAM circuit checked good. The text at the top of the screen for Player 1, High Score and Player 2 were doubled. The "free play" text and the player scores were missing. Replaced bad 74LS157 in the center of the VRAM addresser to restore characters and fix the text issues. Pin 12 was stuck.

Replaced IC 3L to fix missing sound problem. Board would boot and play, but had sparkles in ghosts and player sprites. Replaced bad ROM at 5F and tested.

Model: Ms Pac Man
Symptom: Garbage on screen

Board played but had corrupt graphics. Replaced shorted 74LS194 at 5B and 5C and a shorted 74LS157 at 5A. Tested

Model: Ms Pac Man
Symptom: Randomly dies with black screen

Could replicate issue by tapping or thumping board. Replaced single wipe socket at 3R with a double wipe and cleaned the tarnished pins on the 74LS161 IC. Tested.

Model: Ms Pac Man
Symptom: Dead. Attempted repair damage

Board had a ham fisted repair attempt done with 3 sockets and multiple pulled traces on the ROMs on row 6.

Trimmed back the traces pulled from the board, installed 3 sockets, and patched 13 damaged traces. Installed two ROMs supplied with the board, programmed a replacement for the missing ROM at 6J, and installed it. Board would try to boot but fail. Replaced 4 bad RAMs and tested. Board would run but would reboot by itself. Replaced bad ribbon cable between the board and the daughterboard and retested.

Model: Pac Man
Symptom: Dead. Attempted repair damage

Board had a very badly done chip replacement attempt. IC 8E was removed, a machine pin socket installed, and a new IC in the socket, but the pads were badly damaged. IC 4A was missing

Board had very rusted ROM chips on rows 5 and 6. Replaced the ROMs with programmed 2532 EPROMs and installed a bipolar PROM at IC 4A. Board would attempt to boot but had garbage on screen. Data bus signal DB4 was malformed.  Replaced bad bipolar RAM at 3H. Board would attempt to boot further, but still would not. Replaced the 74LS245 at 4H which cleaned up the data bus signals but it still would not boot fully.

Tested the 2114 RAM and replaced 1 bad one. Removed the poorly installed 74LS367 at 8E and the board would boot further but the screen was still scrambled. Replaced bad NVC284 IC with a V-RAM Addresser daughter board to unscramble the screen. Found a solder short on data bus signal DB2 on the poorly installed IC at 8E. Removed the solder short and the game would then boot, but had incorrect ghost names, no sound, ghosts with wrong colors, and ghosts that moved poorly.

Replaced the 74LS75 at 3D to fix the colors. Replaced the bipolar RAM at 3F to fix the ghost movements. Replaced the bipolar RAMs at 2K and 2L to restore the sound. Removed the poorly installed socket at 8E and found the trace for the control signal for IC 8D was broken and shorted to pin 2 of 8E. Removed the short, soldered the IC at 8E directly to the board, and patched the control signal trace for IC 8D to fix the incorrect ghost names.

Model: Ms Pac Man
Symptom: Dead. Missing parts. Attempted repair damage

Pads were damaged on the ROM sockets on row 6 and there was one shorted solder connection between pins 1 and 2 of the ROM at 6E. Removed the 4 non-original sockets on row 6 to discover many damaged traces. Trimmed the traces that were sticking up off the board, installed new sockets, and patched 8 traces. Replaced a bad 74LS259 at 8K, installed a missing Sync Bus Controller, V-RAM Addresser, and ROMs on row 6. Replaced the hardened ribbon cable to the daughterboard, and tested.

Model: Ms Pac Man
Symptom: Crashing/Rebooting

Board would crash and reboot when using the Ms Pac Man daughter card, but would play fine as Pac Man. Daughter card and ribbon cable tested fine on another board. When using the logic probe with a finger touching the tip (adding extra capacitance) and probing address line A8 input on pin 6 of the 74LS367 at 6R, the game would boot an run perfectly as Ms Pac Man. Replaced bad ROM at location 6H and tested.

The ROM passes self tests, would run fine without the Ms Pac daughter board added in, but had a bad gate on the input pin for address line A8 which caused problems when running at speed with the extra length of ribbon cable and the added chips on the daughter board.

Model: Galaxian
Symptom: RAM Error

Replaced bad RAM at 4F. Board would play, but the player's missile was represented by a stripe crossing the whole screen and during game play the game lost partial colors and would look like it had a yellow hue. Enemy shells were missing from screen. Found the /MLD and /SLD signals were incorrect and HBLANK was missing. Replaced bad 74LS74 at 3D and tested game. Replaced all electrolytic caps except the 2 large filters and retested.

Model: Ms Pac
Symptom: No sync

Replaced bad 74LS161 at 2S. Repaired damaged edge connector power connection with copper tape. Tested.

Model: Ms Pac Man
Symptom: Dead. Garbage on screen

Cleaned and reseated RAM at 4N. Board would play but had stripes through characters. Cleaned and reseated ROM at 5F. Tested.

Model: Super Pac Man
Symptom: Static on audio output. Amplifier chip gets very hot.

Recapped the board and static was still present. At loud volumes the audio would have a repetitive thump thump sound. Replaced 2 missing capacitors on the audio amplifier's output to fix the amplifier chip's self oscillation problem. Tested board.

Model: Pac Man
Symptom: Dead

Reinstalled CPU with the correct orientation to pin 1. Cleaned the MASK ROMs and the NVC285 custom IC legs. Set the dip switches, installed zip ties on the VRAM Addresser card, and tested.

Model: Ms Pac Man
Symptom: Constantly reboots

Board was stuck in watchdog. Replaced bad 74LS138 and board would still reboot, but was rebooting because of a data bus problem instead of a watchdog reset. Data Bus line DB5 wasn't working correctly. Replaced 2 shorted capacitors on the control inputs and 1 shorted capacitor next to the ROM sockets on row 6. Replaced 1 bad 7489 bipolar RAM on the board and 2 74LS374 and 1 74LS244 on the Sync Bus Controller board to finish the repair.

Model: Pac Man
Symptom: Dead

Board had no reset signal. Replaced bad 74LS74 at 5M and a 74LS161 at 9C. Tested

Model: Pac Man
Symptom: All 5s on the screen

Replaced all 6 RAM sockets at customer request. Replaced bad ROM at 6E. Tested. Board played but had odd pitches to the music. Replaced bad PROM at 1M and tested.

Model: Pac Man
Symptom: No vertical sync

Replaced bad 74LS161 at 2S. Tested.

Model: Galaga
Symptom: Missing colors on output. Board had terrible attempted repair damage.

CPU board was a converted Bosconian and had the extra chips cut off and pins left behind. It also had been repaired in the past with all 24/28/40/42 pin sockets replaced. Cleaned up the extra pins from the cut chips and checked the board.

The interconnect cable had a burned wire from a previous short circuit and was replaced.

Video board had all the 2147 RAMs removed with many lifted pads. 2148 RAMs were installed and 3 74xx logic chips were replaced and they were all socketed using 8 pin sockets. (!?!?!?!) Cleaned up the poor solder from where the 2147s were pulled. Removed the 8 pin sockets, cleaned up the solder pads, and installed correct sockets. Installed a missing 470uf capacitor and replaced the 74LS365 at 6A. Patched a bad trace on pin 1 of the 2148 and replaced a bad PROM to fix the color issues. Replaced the 24 and 28 pin sockets, old style resistor packs, installed 2 missing PCB standoffs, and tested.

Model: Bosconian
Symptom: Crashes upon starting a game. Board had massive attempted repair damage to the CPU board.

Board had multple incorrect resistor packs: ten pin packs instead of nine, 6 pin packs in stead of 5 and the extra legs cut off and floating above the board. One 2200 ohm resistor pack had a bad section and a 1k ohm resistor soldered across its pins on the bottom side of the board(!?!?!?). Replaced the remaining, old style resistor packs. Replaced 2 never replaced ROM sockets, 3 never replaced CPU sockets, and 1 incorrect (cut down 48 pin) 42 pin socket on the CPU board. Reseated one of the 8xx chips that had a bent pin and fixed a couple of bad traces that were damaged when someone previously removed one of the 8xx chips (affecting a data line on the 3rd CPU) and one of the resistor packs by the edge connector.

Replaced the 24/28 pin sockets and all the old style resistor packs on the video board. Tested.

Model: Pac Man
Symptom: Dead

Board had previous work done to it. The 74LS74 and 74LS368 ICs were poorly repaired for broken pins.

Replaced the 74LS74 at 8C and 74LS368 8B and their sockets. Replaced the 74LS161 at 3S. Replaced the socket for the VRAM Addresser and replaced the broken socket on the bottom of the daughter board. Replaced the 4 corroded mask ROMs with EPROMs. Tested. Zip tied the 2 daughter boards to the main board. Re-tested.

Model: Super Pac Man
Symptom: Missing sound

Replaced missing cap at C26. Sound worked but was distorted. Replaced bad 15xx custom IC at 3N. Tested.

Model: Super Pac Man
Symptom: RAM Error 1

Replaced bad RAM on video board and 2 bad RAMs on the CPU board. Tested. Audio was garbled. Replaced bad PROM at 3M and retested.

NOTE: Super Pac Man will stop when it finds a RAM error. Replace the bad RAM and continue to reboot/repair until all RAM errors are gone. ROM tests will probably act the same way.

Model: Bosconian
Symptom: Dead

Replaced all 24/28/40/42 pin sockets and old style resistor packs on CPU and Video board. Replaced missing SRAM on CPU board. Recapped audio section. Tested. Board had graphic corruption on text and graphics. Replaced bad PROM at 7H and tested.

Model: Galaga
Symptom: Crashes/reboots

Replaced all 24/28/40/42 pin sockets on the CPU and video boards. Replaced all the old style resistor packs on the CPU board and video board. Repaired broken pins on the 54XX chip and the 04XX chip. Tested.

Model: Galaga
Symptom: Dead. Garbage on screen

Replaced all 24/28/40/42 pin sockets on the CPU and video boards. Replaced all the old style resistor packs on the video board. Installed new interconnect cable and replaced a bad 74LS245 on the video board. Repaired 2 broken traces on the video board. Tested. Recapped the audio section and replaced the 2 470uf power filter caps. Retested.

Model: Galaga
Symptom: Missing player/text graphics

Fixed 3 broken pins on the 54xx, 1 ea. on 2 of the 8xx chips. 1 trace on the 51xx chip where the socket was replaced by 2 old single wipe cut down sockets. The CPU sockets were dual wipe and OK. Replaced the 28 and 42 pin sockets and all the old style resistor packs. It booted with a ROM 03 error. Pulled the ROM at 3L out of the socket and fixed a bent pin. Replaced the 24 pin sockets to finish the CPU board.

Replaced the 24/28 pin sockets and the old style resistor packs on the video board. Fixed a broken pin on the 00xx and 05xx chips. Fixed a bad trace on the 1K resistor pack. Tested the boardset and found the sound for the player ship being captured by the enemy was incorrect. Replaced mismatched sound ROM at 3E and retested.

Model: Pac Man
Symptom: Graphic Corruption

Socket on 5F was previously replaced.

Found 3 damaged traces on 5F. Jumpered traces and tested. Graphics were better but still slightly corrupt. Removed socket from 5F, removed damaged trace causing short, and reinstalled socket. Tested. Sound was corrupt. Replaced bad 74LS86 at 4F and retested.

Model: Pac Man
Symptom: Dead

Fixed 3 broken solder joints on the Sync Buss Controller board. Game would boot the Six Pac mod, but had graphic corruption. Replaced bad CPU and retested. The upper address lines were not working correctly and bank switching was failing.

Model: Mortal Kombat
Symptom: Low audio

Cleaned under a leaky 220uf cap on the audio board, recapped the audio board, and tested.

Model: Mortal Kombat
Symptom: Crackling and low audio

Cleaned under the leaking 100uf and 220uf caps on the audio board, recapped the audio board, and tested.

Model: Mortal Kombat
Symptom: Low audio until board warms up

Cleaned under the leaking 220uf cap on the audio board, recapped the audio board, and tested.

Model: Mortal Kombat
Symptom: Low and crackling audio

Cleaned under 3 220uf, 1 2200uf, and 5 100uf caps that were leaking on the audio board. Recapped the audio board and tested.

Model: Pac Man
Symptom: Burnt edge connector

Repaired the edge connector with copper tape and tested.

Model: Ms Pac Man
Symptom: Burnt edge connector

Repaired edge connector with copper trace tape. Tested.

Model: Ms. Pac Man
Symptom: Dead

Replaced missing Z80 Sync Buss Controller module and the 28 pin socket in mounts to. Replaced a bad 74LS283 in the sound circuit. Tested.

Model: Carnevil
Symptom: No sync.

Replaced bad 7407 IC and tested.

Model: Rampage World Tour
Symptom: Random errors that change with board flexing

Reflowed U1, U13, U24, U25, U32, U33, U36, U37, U38, U39, U65, and U66. Tested.

Model: NBA Hangtime
Symptom: Bad background noise in audio

Replaced bad TL092 OpAmp at U92. Tested.

Model: Galaga
Symptom: Freezes, randomly coins up by itself.

Board has had repair attempts before. All the 2147 RAMs were pulled and 2x 2148 RAMs installed by another tech.

Replaced all the 24, 28, 40, and 42 pin sockets. Replaced all the old style resistor packs. Found a 2.2K pack that had a broken pin causing the freezes and a 5 pin 1K pack with 2 broken pins causing color issues that the previous tech replaced the RAM for. Recapped the board. Repaired bad pin on the 52xx causing the coinup issues. Repaired a bad pin on the 04XX chip. Tested.

Model: Galaga
Symptom: Freezes and resets on its own

Board had been worked on in the past by another tech.

Replaced the 24, 28, and 40 pin sockets on the CPU board. The resistor packs were of the proper type and the remaining sockets were machine pin and did not need replacing. Found all of the 24 pin sockets on the EPROMs were incorrectly installed, standing off the board about 1/16", and two of them had pins that had broken off under the socket causing the bad behavior. Tested board.

Model: Rampage World Tour
Symptom: Graphical Corruption during game

Board had stripes and bleeding colors throughout playfield and outside of the playfield around the screen borders.

Replaced U32, U10, U11, U14, U15, U38, and U75. Tested.

Model: Mortal Kombat 4
Symptom: No sync, burned component.

Rebuilt burnt traces and pads, replaced a burnt 0 ohm resistor in the video ground circuit, and replaced a missing surface mount capacitor. Tested board. Replaced bad surface mount 7407 IC to fix missing sync. Retested to find sync fixed but some buttons not working. Cleaned JAMMA edge connector and tested board again.