Author Topic: SNK Games (Neo Geo MVS/AES) (Read 127244 times)

channelmaniac · « **Reply #280 on:** September 02, 2015, 06:45:55 PM »

Model: MV4
Symptom: No audio on slots 1 and 2.

Cust states: No audio at all after installing cap kit.

Replaced 1 4.7uf cap that was twisted on top of the board. Resoldered 3 cap legs where solder was on the leg but it wasn't soldered to the pad on the board. The board had sound now during test mode but had screen shake when volume was turned up. Replaced 3 470uf power filter caps in the audio section and retested.

Removed the fishpaper and foam from the bottom side of the top board as it had started to corrode chip pins. Checked the area for trace damage and found none. Inspected the top side of the board and found a corrosion spot where something had damaged the board. Jumpered three damaged traces and tested.

Installed coin cell battery kit and retested.

channelmaniac · « **Reply #281 on:** September 09, 2015, 05:20:54 PM »

Model: MV4
Symptom: Dead. Backup RAM Error

System was missing the /CS signal on pin 20. Jumpered a bad trace from the backup battery circuit to the 74HC32 controlling the enable lines to the SRAM. Error still there. Replaced the SRAM IC and tested. Board had graphical corruption. Tested with a known good top board and found the problem to be on the bottom board. Patched corroded trace to fix graphic corruption.

Top board was reconnected, the slots were intermittent, and I noticed an oily coating on the board from some kind of contact cleaner. Cleaned the top board and discovered slots 2 and 3 had graphical corruption. Patched two corroded traces and retested.

channelmaniac · « **Reply #282 on:** September 11, 2015, 08:59:15 PM »

Model: MV6
Symptom: Won't read carts.

Board had attempted repair damage. Someone had replaced the 74AS245 data latches on the bottom board between the CPU and the Program ROM data lines coming from the top board.

Patched 4 damaged traces on the 74AS245 chips on the cartridge data buss. Cartridges would read on some slots and not others. Cleaned the top board and slots. Cartridges would now read but slot 5 had garbled graphics and the audio was low on the right channel. Patched damaged trace on the top board to fix slot 5 and turned the PCB standoffs under the cart slots to keep them from rubbing other nearby traces.

Installed audio cap kit and retested.

channelmaniac · « **Reply #283 on:** October 18, 2015, 06:41:06 PM »

Model: MV4
Symptom: Z80 Error. Only 2 slots working.

Replaced the Z80 CPU and tested. No audio. Used a logic probe with audio to check the input of the Yamaha DAC and heard the digital audio present. Recapped the audio section to restore audio. Cleaned the top board and slots to fix the slot issues. Tested with cartridges to find the audio was scrambled up. Replaced the YM2610 sound chip and retested.

Replaced the NiCd battery with a coin cell conversion, reset the backup RAM, and retested.

channelmaniac · « **Reply #284 on:** November 13, 2015, 10:52:11 PM »

Model: MV6
Symptom: No audio in left channel. Solder on the edge connector.

Board cover was damaged in shipping.

Recapped the audio section, desoldered lumped solder from the edge connector, and tested. Straightened bent metal cover and one bent standoff. Replaced 12 missing screws, 4 plastic washers, and 4 nuts. Retested.

channelmaniac · « **Reply #285 on:** November 28, 2015, 12:52:09 AM »

Model: MV2F
Symptom: Lines through text layer

Patched a corroded trace and tested.

channelmaniac · « **Reply #286 on:** November 28, 2015, 12:53:37 AM »

Model: MV2
Symptom: Lines and garbage on the screen while game plays.

Problem would come and go when the board was tapped or flexed.

Resoldered 2 sides of the LSPC-A0 surface mount IC to fix multiple popped solder joints. Tested.

channelmaniac · « **Reply #287 on:** November 28, 2015, 12:55:09 AM »

Model: MV4
Symptom: No Audio

User installed a cap kit on the board.

Logic probe on pin 4 of the YM3016 DAC showed no digital audio was making it to the DAC from the YM2610 IC. Replaced the YM2610 IC and tested.

channelmaniac · « **Reply #288 on:** December 13, 2015, 10:34:57 PM »

Model: MV1
Symptom: leaking battery

Replaced battery with a coin cell mod, recapped the board, and tested.

channelmaniac · « **Reply #289 on:** December 13, 2015, 10:36:26 PM »

Model: MV1
Symptom: Stuck on Green (Calendar Error), missing audio amp IC.

Replaced 32.768KHz crystal, 2 capacitors, the D4990 IC, and cleaned around those components to fix the Calendar error. Replaced leaking battery with a coin cell mod kit, installed missing audio amp IC, and recapped the board. Tested.

channelmaniac · « **Reply #290 on:** December 13, 2015, 10:40:16 PM »

Model: MV1
Symptom: Video RAM Error 00000001 Written 5555 Read 5554. Missing 3 ICs in the audio section.

Replaced bad lower surface mount Video RAM IC to only receive another Video RAM error, this time with the upper Video RAM IC. Replaced the upper surface mount Video RAM IC. Board booted to a Z80 Error. Patched corroded trace on the Clock signal to the Z80 and tested. Z80 error was still present. Replaced the Z80 CPU and retested.

Board booted but had no audio. Replaced missing YM3016 DAC, 2066 headphone amplifier IC, and HA13001 audio AMP IC. Tested board and had audio, but it was low. Recapped board to finish the repair.

channelmaniac · « **Reply #291 on:** December 20, 2015, 10:38:02 PM »

Model: MV1
Symptom: Dead

Board would randomly fail with Backup RAM errors at different locations, if it would even boot. Replaced 2 Backup RAMs, installed coin cell battery kit, and recapped the audio section. Tested.

channelmaniac · « **Reply #292 on:** December 20, 2015, 10:40:35 PM »

Model: MV1
Symptom: Dead.

Board would sometimes fail with click of death and other times with a solid white screen.

The enable signal was missing on the SFIX ROM. Patched 5 damaged traces on the bottom of the board and the board would boot to a green screen - A calendar error. Replaced a battery leak damaged 22pf capacitor and the 32.768KHz crystal in the clock/calendar circuit to fix that. Installed a coin cell kit, replaced the DIP switches, and recapped the audio section. Tested.

channelmaniac · « **Reply #293 on:** December 20, 2015, 10:42:46 PM »

Model: MV1
Symptom: Low audio. Leaking battery.

Cleaned battery damage and replaced it with a coin cell kit. Patched one damaged trace to the DIP switches. Recapped audio section to fix low audio and tested.

channelmaniac · « **Reply #294 on:** December 20, 2015, 10:45:31 PM »

Model: MV1
Symptom: Leaking battery.

Cleaned battery damage and replaced it with a coin cell kit. Recapped audio section and tested.

channelmaniac · « **Reply #295 on:** January 01, 2016, 04:52:29 PM »

Model: MV4
Symptom: No audio

Recapped audio section. Board had audio, but was playing test tones incorrectly. Replaced bad YM2610 and tested. Board would not boot cartridges. Cleaned top board and slots and retested. Replaced missing hardware and retested.

channelmaniac · « **Reply #296 on:** February 07, 2016, 10:56:27 PM »

Model: MV2
Symptom: Vertical lines in graphics and Video RAM Error $8000

Replaced 2 CXK-5814 SRAM chips to fix the Video RAM error. Reflowed broken pins on the NEO-B0 and LSPC chips then replaced a defective NEO-ZMC2 chip to fix the graphics error. Tested.

channelmaniac · « **Reply #297 on:** February 07, 2016, 10:58:46 PM »

Model: MV4
Symptom: Video RAM ERROR $00000601

Replaced bad 62256 type surface mount SRAM IC and tested.

channelmaniac · « **Reply #298 on:** March 19, 2016, 11:30:27 AM »

Model: MV4 & Metal Slug X cartridge
Symptom: Z80 Error

Replaced bad Z80 IC and tested only to find no audio outputs. Recapped board and tested but the board would not boot past the grid screen. Disassembled cartridge and cleaned the edge connectors witt a pink pencil eraser then successfully tested the game.

channelmaniac · « **Reply #299 on:** March 28, 2016, 06:29:58 PM »

Model: MV2
Symptom: Lines in graphics.

Board had battery leak damage and had a coin cell mod done to it previously. Cartridge with game was reported to crash if slightly bumped.

Patched 6 damaged traces between the NEO-B0 and the NEO-ZMC2 IC and tested. Game was missing coin up sounds and other sounds in game. Replaced the YM2610 sound generator IC and retested. Cleaned cartridge edge contacts with a pink pencil eraser and resoldered the sound ROMs to fix cracked solder joint problems. Tested.

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Author Topic: SNK Games (Neo Geo MVS/AES) (Read 127244 times)