SNK Games (Neo Geo MVS / AES)

[channelmaniac]

Model: MV4
Symptom: Stuck on Crosshatch

Board had a leaking battery that was already removed before it was shipped in.

Cleaned bottom board. Cleaned top board and slots. Patched 3 bad traces that were damaged by the battery leaking. Tested.

[channelmaniac]

Model: MV2
Symptom: Color RAM error

Jumpered corroded trace between pin 51 of the CPU and pin 24 of the the NEO-B0 chip. Board booted with a Z80 error afterwards. Repaired a corroded trace between address line A3 of the sound RAM and sound ROM chips. Tested.

[channelmaniac]

Model: MV2F
Symptom: Audio issues

Installed an audio cap kit, remote battery, and replaced a broken headphone jack. Upgraded the system BIOS to a UniBIOS at customer's request using customer's supplied code. Repaired a broken trace to DIP Switch 8.

[channelmaniac]

Model: Super Sidekicks 3 cartridge
Symptom: Graphic Corruption

Game had lines in the background graphics. Resoldered the Graphics ROMs to fix cracked solder joints. Tested.

[channelmaniac]

Model: MV6
Symptom: Dead, stuck in watchdog

Board had burned resistors on the sync line from what appeared to be a faulty monitor connection. A previous repair attempt was made where the resistors had been replaced.

Removed a huge wire jumper from the board. Replaced a shorted 74AS244 IC, blown 74LS86 IC, and a shorted CPU. Installed a 30ga Kynar jumper to replace a burned trace. Cleaned the top board/slots. Replaced battery with a Coin Cell kit. Tested.

[channelmaniac]

Model: MV4
Symptom: Dead. Will not power up.

Board had a diode installed between power and ground on the edge connector. This diode was shorted.

Removed shorted diode. Board would power up but had low volume issues. Recapped sound section. Board would play but had static in audio and was missing some sounds. Replaced bad YM2610 IC. Cleaned both boards and replaced battery. Tested.

[channelmaniac]

Model: MV4F
Symptom: Random sounds and memory errors. Won't always recognize carts.

Removed leaking battery and cleaned top/bottom boards which fixed sound/cart issue, but the volume was low and would make popping sounds that affected the picture on the screen. Installed an audio cap kit and removed 2 bad mylar caps from the audio output circuit and tested.

Board would randomly crash upon warming up. Set all DIP switches to on to force a Work RAM test loop which tests Work RAM and Backup RAM. Board failed with a Backup RAM error after 10 minutes. Replaced bad Backup RAM and tested.

[channelmaniac]

Model: MV6
Symptom: Stuck on crosshatch

Cleaned top board and tested. Replaced battery at customer's request.

[channelmaniac]

Model: MV1
Symptom: Z80 Error

Removed leaking battery and cleaned residue off of board. Cleaned slots and tested. Replaced battery.

[channelmaniac]

Model: MV2F
Symptom: Backup RAM Error B240

Replaced bad 74HC32, 2 corroded transistors, 1 cap, and 1 open 22k ohm resistor in the battery backup circuit. Removed the 470 ohm resistor in the charge circuit and installed a coin cell battery kit. Tested.

[channelmaniac]

Model: MV-2F
Symptom: No audio from slot 2

Checked connections between the slots and the NEO chipsets. Continuity was good. Replaced bad NE0-257 IC and tested.

[channelmaniac]

Model: MV2F
Symptom: Horizontal graphical corruption.

Graphics had horizontal tears in graphics. Replaced NE0-E0 chip and the LO ROM. Tested.

[channelmaniac]

Model: MV4
Symptom: No audio

Recapped the sound section and cleaned top board and slots. Reassembled boardset and replaced incorrect hardware, missing hardware, and 1 broken mounting foot. Tested.

[channelmaniac]

Model: MV4
Symptom: Lines on screen and no sound

Cleaned top board and slots to fix graphic issue. Recapped bottom board to fix audio issue. Tested. Replaced one broken board standoff, 3 missing top cover screws, and a missing mounting foot.

[channelmaniac]

Model: MV4
Symptom: Backup RAM Error 00D01C0A AAAA EAAA

Replaced bad surface mount SRAM IC and tested. Board had low audio. Recapped audio section and retested. Ran board on an extended Work RAM test to check those RAMs.

[channelmaniac]

Model: MV1AX
Symptom: Backup RAM Error

Replaced bad RAM 3 and patched 2 corroded traces.

Board had the rechargeable lithium battery replaced with a standard coin cell, but did not have the charging circuit neutered. Removed D1, D2, and R10 to disable the circuit. Battery terminals still had 4.38v on it when the board was powered on. Replaced shorted diode D4 and tested. Reinstalled coin cell better and tested power to the Backup RAMs.

[channelmaniac]

Model: MV4F
Symptom: Bad slot, low audio

Recapped audio section of the board. Replaced battery with a new NiCd per customer request, and replaced a physically damaged cartridge slot. Cleaned top board and tested.

[channelmaniac]

Model: MV4
Symptom: Dead. Garbage on screen.

Board had some attempted repairs done.

Reflowed the solder on 2 surface mount SRAMs that someone had attempted to replace. Resoldered the positive lead on the NiCd battery, recapped the audio, and tested.

[channelmaniac]

Model: MV4
Symptom: Bad slot

Replaced bad slot connector, cleaned top board, and tested.

[channelmaniac]

Model: MV4
Symptom: Bad slot

Slot 1 had garbage on the screen. Cleaned top board, replaced bad 74LS244 at location A4, and tested.

[channelmaniac]

Model: MV1F
Symptom: Dead

Removed foreign substance from a Neo chipset chip and tested.

[channelmaniac]

Model: MV4
Symptom: Dead. Would randomly boot with graphic corruption

Resoldered the PRO-C0 and LSPC-A0 ICs to fix their cracked solder. Tested.

[channelmaniac]

Model: MV1F
Symptom: Z80 Error

Board had severe battery damage. Cleaned battery damage, patched 5 traces on the sound system's SRAM chip, and tested.

[channelmaniac]

Model: MV4
Symptom: Low Audio. Attempted Repair Damage

A ham fisted attempt had been made at replacing the audio caps. They had only replaced about 2/3rds and had damaged many solder pads and plated thru holes.

Removed all audio caps and other badly replaced caps. Installed new caps, patched traces, and soldered some caps in on the top side of the board where the plated thru holes were removed. Tested board and found that some sound effects were incorrect. Tested with a known good top board and narrowed problem to the bottom board. Replaced the YM2610 IC and retested.

[channelmaniac]

Model: MV4
Symptom: Video RAM Error 8000 5555 5500

Top board had a patched trace from a previous tech

Replaced bad CXK5814 SRAM chip. Audio levels were low so a cap kit was installed. Board had lines in the graphics on slot 4. Removed deteriorated foam that was corroding things from the under side of the op board, cleaned the glue/foam residue with solvent, cleaned board and slots, then checked the board traces. Re-ran the existing patch from a via to the chip instead of the slot to the chip as it was much shorter, then patched 2 additional traces. Tested.