Author Topic: SNK Games (Neo Geo MVS/AES) (Read 126833 times)

channelmaniac · « **Reply #340 on:** July 03, 2018, 06:10:11 PM »

Model: MV4
Symptom: Backup RAM Error

Repaired broken trace between the 74HC32 and the Backup RAM. Installed 6 missing feet and standoffs. Tested.

channelmaniac · « **Reply #341 on:** July 03, 2018, 06:10:40 PM »

Model: MV4
Symptom: No Audio

Cleaned top board. Recapped audio section then installed a coin cell kit. Tested. No Audio. Repaired bad trace between Z80 and Sound RAM then retested successfully.

channelmaniac · « **Reply #342 on:** July 03, 2018, 06:12:20 PM »

Model: MV4
Symptom: Crosshatch of death

Patched trace to fix crosshatch issue. Clock was counting hyper fast. Replaced bad D4990 Clock/Calendar chip. Cleaned top board, installed 6 feet and standoffs, installed coin cell kit, and tested.

channelmaniac · « **Reply #343 on:** July 03, 2018, 06:13:21 PM »

Model: MV4
Symptom: No audio

Cleaned top board. Recapped audio section, installed coin cell kit, and tested.

channelmaniac · « **Reply #344 on:** July 03, 2018, 06:14:46 PM »

Model: MV4
Symptom: Dead

Cleaned top board, installed missing BIOS chip, and tested - Video RAM errors and color errors. Replaced the sprite RAM, 1 74LS273, and 1 74LS05 to fix the video issues and tested - no audio. Replaced bad YM2610 and recapped audio section. Installed coin cell kit and tested.

channelmaniac · « **Reply #345 on:** September 09, 2018, 08:44:07 PM »

Model: MV2
Symptom: Lines on screen. Board had battery damage.

Replaced a bad NEO-ZMC2 IC and patched one trace. Tested.

channelmaniac · « **Reply #346 on:** September 21, 2018, 11:55:49 PM »

Model: MV4
Symptom: Work RAM Error

Replaced both Work RAMs. Board came up with a Video RAM error at 000000. Replaced bad Video RAM and tested. Board was stuck on green - a calendar error. Removed leaking NiCd battery and patched 2 traces for the Clock/Calendar circuit that traversed the battery area. Tested board and it was stuck on the crosshatch of death. Patched one dead trace under the old NiCd battery and successfully tested the game.

channelmaniac · « **Reply #347 on:** September 21, 2018, 11:58:13 PM »

Model: MV4F
Symptom: Dead. Displays an orange screen.

Replaced corroded BIOS socket and cleaned the legs on the ROM. Noticed that when the NEO-B1 chip was touched the screen went crazy. Reflowed 1 1/2 sides of the NEO-B1 and NEO-LSPCA2 chips and tested. The left audio channel was missing. Installed a cap kit and retested successfully.

channelmaniac · « **Reply #348 on:** December 21, 2018, 04:00:09 PM »

Model: MV4
Symptom: Low volume out of one channel. The other is dead.

Recapped the audio section and tested. Music was present but game effects were not.. Replaced the YM2610 sound chip to fix the missing sound effects. Replaced battery with coin cell kit, cleaned the top board, and reassembled/tested.

channelmaniac · « **Reply #349 on:** December 21, 2018, 07:05:55 PM »

Model: MV2F
Symptom: Lines in graphics

Checked inputs and outputs to the NEO-257 ICs and inputs to the NEO-ZMC2. All appear OK. Checked output traces from the NEO-ZMC2 and they were good. Replaced bad NEO-ZMC2 and tested. Removed the leaking NiCd battery and replaced it with a coin cell kit after neutering the charging circuit.

channelmaniac · « **Reply #350 on:** December 22, 2018, 12:48:54 AM »

Model: MV1
Symptom: Stuck on green

Removed the leaking battery, 2 corrosion damaged capacitors, and the bad clock crystal from the board. Cleaned and installed replacement caps/crystal. Patched trace to fix DIP switch 1. Recapped audio to fix low left channel issue and installed a coin cell kit. Tested.

channelmaniac · « **Reply #351 on:** December 25, 2018, 11:40:29 PM »

Model: MV4
Symptom: Stuck on crosshatch.

Board had physical damage - burned ground contacts on the JAMMA connector and bodge wires soldered in to bypass them.

Removed bodge wires and repaired edge connector with copper trace tape. Removed battery connection pins and 470 ohm resistor. Tested the traces under the battery and found one bad. Patched the trace and tested. The board played but was missing sound and had lines in the graphics. Cleaned the top board and slots then retested without any issues. Installed the coin cell holder and battery and re-tested game.

channelmaniac · « **Reply #352 on:** December 27, 2018, 12:09:23 AM »

Model: MV4F
Symptom: Reboots when playing carts in slot 3 if you have credits on the right side coin mech

Turns out it reboots even without using the right side coin mech - it's dependent on cartridges. Metal Slug works fine but Shock Troopers and Samurai Shodown 3 cause a reboot and Shock Troopers 2nd Squad causes it to go into a click of death until power cycled.

Narrowed problem down to the top board and found a floating pin 6 on the NEO253 at E5. When the logic probe (with finger touching it) is touched to pin 6 the cartridge boots without issues. Pulled the program cartridge board slot from the top board to find the break in the trace and its destination. Patched trace between pin 6 of the NEO253 at E5 and cartridge connection B27 (PWAIT1 signal) to fix the boardset. Tested by playing Shock Troopers 2nd Squad through to the end.

channelmaniac · « **Reply #353 on:** December 27, 2018, 08:59:23 PM »

Model: MV4F
Request: Change battery, change broken connector, and check out.

Removed NiCd battery & 470 ohm resistor then installed a CR2032 holder and battery. Replaced broken 60 pin ribbon cable connector. Cleaned top board/slots and tested. Audio was low on left channel so an audio cap kit was installed. Replaced PCB feet and stripped screws and tested.

channelmaniac · « **Reply #354 on:** January 31, 2019, 01:17:18 AM »

Model: MV1
Symptom: Z80 Error

Replaced bad Z80 CPU and tested. Patched dead trace on DIP 1 and installed audio cap kit to fix low audio. Installed coin cell battery kit and tested.

channelmaniac · « **Reply #355 on:** January 31, 2019, 01:18:59 AM »

Model: MV4
Symptom: Crosshatch of death

Cleaned battery damage and patched 3 dead traces. Tested but board stopped working during testing. Replaced upper and lower 64 pin connector next to battery as corrosion had migrated up inside the connectors. Retested. In stalled coin cell battery kit and retested.

channelmaniac · « **Reply #356 on:** January 31, 2019, 01:21:39 AM »

Model: MV4
Symptom: VRAM ERROR

Replaced bad surface mount 62256 chip to fix the video error and tested. Game played but had low audio. Installed audio cap kit and coin cell battery kit. Tested all four slots - slot 3 was dead. Cleaned the top board and slot 3 would play but had graphical errors. Replaced a bad slot connector and retested.

This one was a bit frustrating. Two pins of the slot connector broke between the connector and the PCB making intermittent connection: A16 and B18, causing the graphic corruption.

channelmaniac · « **Reply #357 on:** April 29, 2019, 09:48:01 PM »

Model: MV2
Symptom: Graphics corruption

The battery had leaked and damaged the board. Cleaned the battery damage, patched one open trace, installed a coin cell battery kit, and tested.

channelmaniac · « **Reply #358 on:** May 22, 2019, 09:07:52 PM »

Model: MV2B
Symptom: Z80 ERROR

Replaced bad Z80 CPU and tested successfully.

channelmaniac · « **Reply #359 on:** October 09, 2019, 09:17:41 PM »

Model: MV1FT
Symptom: "Swap battery and check board"

Board had no audio output. Speakers would pop slightly like normal when power was applied or removed. Logic probe on the YM3016 DAC showed no audio data was arriving from the YM2610. Hardware tests produced no audio. Removed leaking NiCd battery and neutered the charging circuit. Cleaned up battery leakage and patched 2 data traces going from the Neo chipset, across the battery, to the audio section to fix the missing audio. Installed a CR2032 coin cell holder and tested board successfully.

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Author Topic: SNK Games (Neo Geo MVS/AES) (Read 126833 times)