Author Topic: SNK Games (Neo Geo MVS/AES) (Read 127597 times)

channelmaniac · « **Reply #260 on:** November 23, 2014, 08:43:43 PM »

Model: Baseball Stars 2
Symptom: Corrupt graphics

Resoldered cracked solder joints on the graphics ROMs. Tested.

channelmaniac · « **Reply #261 on:** November 23, 2014, 08:44:05 PM »

Model: League Bowling
Symptom: Corrupt Graphics

Cleaned cart edge connectors and tested.

channelmaniac · « **Reply #262 on:** December 06, 2014, 12:14:16 PM »

Model: MV4F
Symptom: Calendar Error / Stuck on green

Replaced bad 32.768KHz crystal, cleaned top board, and tested. Recapped audio section to fix a low audio output issue. Retested

channelmaniac · « **Reply #263 on:** December 06, 2014, 12:18:38 PM »

Model: MV4
Symptom: Garbage on screen after board was cleaned by cust.

Board had garbage on screen that matched a Video RAM error screen where the RAM is bad. Looked over the memory with a logic probe and noticed that bridging adjacent data pins did not result in a change on the screen. Checked the LSPC chip and found multiple lifted legs and missing factory solder on many legs. Straightened 2 bent pins and reflowed the side of the LSPC with the missing solder issues. Tested and found audio output was very low. Recapped the audio section and installed a coin cell battery kit at customer's request. Retested board.

I've seen a few Capcom 1943 and other boards of that era with missing solder on pins of SMT ICs, but this is a first for seeing this on an SNK board.

channelmaniac · « **Reply #264 on:** December 07, 2014, 10:58:03 PM »

Model: MV4
Symptom: Will not read carts

Cleaned the top board and slots. Removed battery, cleaned under the battery, and patched one damaged trace. Disabled the charging circuit, pnstalled a coin cell battery, and tested.

channelmaniac · « **Reply #265 on:** January 04, 2015, 05:48:42 PM »

Model: MV4 with Blazing Star cartridge.
Symptom: No audio. Will not play carts.

Cleaned the top board and slots. Installed a coin cell battery mod and recapped the audio section of the board. Replaced 5 cross-threaded screws, 1 standoff, and 2 broken mounting feet. Tested.

Opened the cartridge, resoldered 6 cracked solder joints, and cleaned the edge connectors. Tested.

channelmaniac · « **Reply #266 on:** January 08, 2015, 10:08:14 PM »

Model: MV1FS
Symptom: Low audio, leaking battery.

Recapped the audio section, removed old battery, cleaned up leakage, and installed a coin cell mod kit. Tested.

channelmaniac · « **Reply #267 on:** March 14, 2015, 11:43:37 PM »

Model: MV2F
Symptom: Lines in graphics

Replaced bad NEO-257 chip and tested. Replaced battery with a coin cell kit and retested.

channelmaniac · « **Reply #268 on:** March 14, 2015, 11:44:54 PM »

Model: MV2
Symptom: Dead

Board would boot once out of every 20 times. Flipped all DIPs and put it into Work RAM test loop and rebooted it repeatedly. Board came up with a Backup RAM error. Replaced bad RAM and tested. Replaced battery with a coin cell kit and retested

channelmaniac · « **Reply #269 on:** March 15, 2015, 12:13:24 PM »

Model: MV2F
Symptom: Backup RAM error

Cleaned board and replaced corrosion damaged 22K ohm resistor in the backup RAM control circuit. Installed a coin cell kit and tested.

channelmaniac · « **Reply #270 on:** April 05, 2015, 08:47:34 PM »

Model: MV4
Symptom: Backup RAM error. Problems reading carts.

Replaced bad backup RAM. Tested board and found slot 3 would not read carts. Replaced 1 connector, 2 74LS245, and 1 74F244 ICs for slot 3 and cleaned the top board/slots. Tested. Boardset worked but graphics were very glitchy on slot 3. Replaced the 2nd connector for slot 3 and retested.

channelmaniac · « **Reply #271 on:** July 29, 2015, 08:49:31 PM »

Model: MV4
Symptom: No audio

Recapped the sound section to restore audio. Walked the board's owner through cleaning a cart using a fiberglass pencil then removed the NiCd battery from the MV4, neutered the battery charging circuit, and installed a CR2032 battery and holder on the bottom side of the board.

Tested.

channelmaniac · « **Reply #272 on:** August 17, 2015, 09:27:30 PM »

Model: MV2F
Symptom: Will not read carts

Removed damaged memory card socket and tested. Removed battery and installed a coin cell modification to the board.

channelmaniac · « **Reply #273 on:** August 17, 2015, 09:29:00 PM »

Model: MV2F
Symptom: Backup RAM error

Board had battery leak damage.

Patched 2 traces to the 74HC32 next to the battery. Board would now boot but had scrambled graphics. Repaired 4 damaged traces connected to the NEO-ZMC2 chip and tested. Removed battery, cleaned around where the battery was, and installed a coin cell modification to the board.

channelmaniac · « **Reply #274 on:** August 21, 2015, 09:45:05 PM »

Model: MV1
Symptom: No sync

Repaired a burnt trace at the JAMMA edge connector to restore sync. Tested board and discovered it had no audio. Repaired a gouged trace on the bottom of the board in the digital sound section and tested.

Did the coin cell battery mod to the board and retested.

channelmaniac · « **Reply #275 on:** August 21, 2015, 09:46:30 PM »

Model: MV4
Symptom: Video RAM Error

Replaced bad surface mount 62256 SRAM and tested. Discovered board had low audio. Recapped the audio section of the board, installed a coin cell battery mod, and retested.

channelmaniac · « **Reply #276 on:** August 23, 2015, 08:44:30 AM »

Model: MV4
Symptom: No audio, battery low, not reading cartridges.

Recapped audio section, removed battery and installed a coin cell mod, and cleaned the top board to fix the cartridge read problem. Tested board. It was playing but missing some audio sounds and others were incorrect. Replaced bad YM2610 audio IC and tested.

Note: For Neo Geo boards, the batteries are NiCd rechargeables and must be run at least 24 hours in a month to keep the battery charged. Replacing the battery with a coin cell and neutering the charging circuit is better if this is for home use. It's also better in that it gets rid of the leak prone NiCd battery that causes horrible damage to the board.

channelmaniac · « **Reply #277 on:** August 23, 2015, 08:45:23 AM »

Model: MV4
Symptom: No sound

Recapped audio section. Boardset would play games but games were missing some sound effects and others were garbled. Replaced bad YM2610 IC and retested. Installed coin cell mod and retested.

channelmaniac · « **Reply #278 on:** September 02, 2015, 06:37:48 PM »

Model: MV4F
Symptom: Corrupt graphics.

Board had low audio and the screen would shake when the volume was turned up.

Recapped audio section and replaced the 3 extra power filter caps to restore audio and fix the shake issue. Cleaned the top board and slots then repaired two gouged traces on the bottom board to fix the graphic corruption.

Installed coin cell battery kit and tested.

channelmaniac · « **Reply #279 on:** September 02, 2015, 06:42:28 PM »

Model: MV4F
Symptom: Backup RAM Error

Written 5555 Read 0000

This was a problem with the control signals going to the Backup RAM. The battery was shorted internally so it was removed. The /OE and /CE lines were OK but the R/W signals were missing. Replaced the 74HC32. Traced the missing signal back from there through the HC32 to a 74HC259. The inputs appeared there on pins 1, 2, and 3 and 13 was high. Noticed that when the 4th input, pin 13 was touched by the logic probe tip the screen would turn white. Replaced the IC, same issue. Double checked and found that pin 13 was floating, but was tied high internally on the IC. Jumpered broken trace to pin 13 and tested the board.

Installed a coin cell battery kit and retested.

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Author Topic: SNK Games (Neo Geo MVS/AES) (Read 127597 times)