SNK Games (Neo Geo MVS / AES)

[channelmaniac]

Model: MV2F
Symptom: Corrupt Graphics

Board had a very strange symptom: Character graphics on the left side of the screen and the background graphics were flipped left-to-right on 8 bit boundaries. Text overlay and health bar resources were fine. When the LSPC2 and NEO-B1 chip were tapped, the system would reset. Resoldered pins on both chips to fix the reset issue but the graphics corruption remained. Checked the H signal from pin 109 of the LSPC2 to pin 7 of the NEO-ZMC2 and it was good. This signal is used for flipping graphics elements.

Replaced the NEO-ZMC2 IC and tested the board. Per customer's request, installed a coin cell battery mod: Removed the 470 ohm charging resistor then installed a CR2032 batter and holder. Reset Backup RAM and set the time/date. Re-tested board.

[channelmaniac]

Model: MV4
Symptom: Garbage on screen. Dead.

Board had battery damage.

Cleaned the corrosion from the bottom board and from the connector on the top board. Pinned out all the traces to find out where the damage was... They were all good. Found a broken trace on D4 between the Work RAM and the Backup RAM. Jumpered the trace, no effect. The solder joints and some of the legs were pretty badly damaged by the battery leakage on the Work RAM and the Backup RAM. Removed the RAM, cleaned up the pads, installed new RAM, reinstalled the jumper on D4, and tested.

[channelmaniac]

Model: MV4F
Symptom: Z80 Error

Replaced Z80 IC and tested. Audio levels were low so a cap kit was installed. Board had audio during self tests but not while playing games. Cleared the Backup Memory from within the Hardware Test Menu and tested the system.

[channelmaniac]

Model: MV1T
Symptom: Garbled audio

Cleaned Stereo/Mono switch and tested. Board had a leaking NiCd battery. Removed the battery, cleaned up the solder pads, removed the 470 ohm charging resistor and installed a CR2032 battery and socket. Tested board.

[channelmaniac]

Model: MV4
Symptom: Video RAM Error

Replaced 1 surface mount SRAM chip and installed an audio cap kit to fix low audio volume issues. Tested.

[channelmaniac]

Model: MV1FS
Symptom: No video sync

Board was covered in an oily residue and had a leaking battery. Cleaned board then patched a bad trace between the LSPC2 and the NEO-IO chips. Removed the 470 ohm charging resistor and installed a lithium coin cell battery and holder. Tested board.

[channelmaniac]

Model: MV2F
Symptom: Video RAM Error $8000

Replaced 2 CXK-5814 SRAMs. Audio had issues. Replaced 2 470uf caps and removed a solder short from the audio amplifier section. Tested.

[channelmaniac]

Model: MV1
Symptom: Video RAM Error $8000

Replaced 2 CXK-5814 SRAMs and tested.

[channelmaniac]

Model: Metal Slug 5 (all-in-1 game board)
Symptom: Graphic corruption

Resoldered 4 broken solder connections on Graphic ROM C4. Tested game.

[channelmaniac]

Model: Metal Slug 3 (bootleg cart)
Symptom: Dead

Resoldered SMT program ROMs and the controller IC for them. Cleaned edge connectors and tested.

[channelmaniac]

Model: Metal Slug 3 (bootleg cart)
Symptom: Dead

Removed shorting solder splashes from an empty program ROM chip location. Resoldered program ROM control chip, cleaned edge connectors, and tested.

[channelmaniac]

Model: King of Fighters 2003 (bootleg)
Symptom: Dead

Resoldered the control IC for the Program ROMs. Fixed one short between the RAM on the cart and the ROM where the wire was to tight going around a sharp pin and the insulation was pierced. Cleaned edge connectors. Game played but with garbled sound effects. Resoldered the sound effects ROMs and their control chip. Tested.

[channelmaniac]

Model: MV4F
Symptom: Z80 Error

Replaced bad Z80 IC. Removed leaking battery, cleaned board, and installed new battery. Cleaned top board and slots. Tested.

[channelmaniac]

Model: Metal Slug 4 boot
Symptom: Dead

Cleaned cart edge connector and tested

[channelmaniac]

Model: Super Sidekicks 2
Symptom: Graphic corruption

Cleaned cart and tested.

[channelmaniac]

Model: 1 slot (bootleg)
Symptom: Graphic corruption

Board came in with a complaint of graphic corruption but was dead. The CPU was a PLCC type and was in a socket. Pulled the CPU, cleaned the severely tarnished legs, and reinstalled. System booted with the graphic corruption. Cleaned the legs on a 27C512 EPROM and tested.

[channelmaniac]

Model: MV4
Symptom: Low audio and graphic corruption

Recapped the audio section of the board and cleaned the top board and slots. Replaced the battery and tested.

[channelmaniac]

Model: MV4
Symptom: Stuck at crosshatch

Replaced connector CN10 on the upper and lower board. Battery corrosion caused it to not make proper connection. Cleaned the top board and slots then tested.

[channelmaniac]

Model: MV4
Symptom: No audio and graphics corruption

Replace NEO-B0 chip to fix graphics corruption. Installed audio cap kit and new battery. Tested.

[channelmaniac]

Model: MV4
Symptom: No audio. Missing parts

Board was purchased as "non-working, no audio" for refurbishing. Replaced missing LM324 op-amp and HA13001 audio amplifier IC. Patched 2 broken traces and installed audio cap kit. Tested board.

[channelmaniac]

Model: MV6
Symptom: No audio

Board was bought for refurbishing and resale. It had already been worked on. Replaced 2 incorrect and 1 backwards cap in the audio section. Still no sound. Checked the YM3016 DAC and it's inputs were dead. Replaced the YM2610 and tested.

[channelmaniac]

Model: MV4
Symptom: Corrupt graphics and lockups

Board has been previously worked and has damage from it. BIOS has been replaced with a UniBIOS chip.

Replaced the surface mount video SRAM previously installed by the other tech. Patched 2 damaged traces. Board booted to a backup RAM error. Replaced the bad backup RAM. Replaced the UniBIOS with a standard BIOS. Board booted to a Video RAM error. Replaced the other surface mount SRAM and tested. Board had very low audio. Recapped audio section and replaced the battery with a new one. Tested board.

[channelmaniac]

Model: MV4
Symptom: Stuck in watchdog

Board has been previously worked on and has damage from it. BIOS is missing.

Replaced missing BIOS and 1 missing video SRAM IC. Jumpered a damaged trace and tested system. System booted with a Z80 error. Removed SIP strips used as a Z80 socket from the board. Removed 2 terrible trace patches and tested each trace coming from the Z80. The traces were damaged when the previous tech used a large screwdriver to pry the Z80 from the board.

Installed a new socket, new Z80, and 2 Kynar wire jumpers. Board still booted to a Z80 Error. Replaced bad SM1 ROM and retested. Board had almost zero audio when turned up full volume. Recapped the audio section and installed a new battery. Tested board.

[channelmaniac]

Model: Metal Slug 4 cart
Symptom: Graphic corruption. Locks up.

Cleaned cartridge edge connector and tested. Cartridge edge connections were too dirty to clean with q-tips and alcohol and had to be cleaned with a pink pencil eraser.

[channelmaniac]

Model: King of Fighters 2000 Cart
Symptom: No audio, severe graphic corruption

Graphics were nothing but scrambled colored dots on the screen and were not recognizable at all.

Jumpered cut trace where the cartridge was mounted. Reflowed surface mount IC NEO-CMC and tested.

Some Neo Geo cartridges have traces that run under the plastic board mounts in the cart shell. These traces can be cut or worn through by the plastic.