Midway Games

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

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

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

Model: Ms Pac
Symptom: No sync

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

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

Model: Pac Man
Symptom: Dead

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

[channelmaniac]

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.

[channelmaniac]

Model: Pac Man
Symptom: No vertical sync

Replaced bad 74LS161 at 2S. Tested.

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

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.

[channelmaniac]

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.