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I'm in a similar boat, also did the shotgun approach of replacing the dram chips, only to have the issue remain. I'm a novice at troubleshooting (using a probe), so will be watching your progress as you investigate the top board. Also many thanks to shadows for posting the top board schematics!

If you don't mind me asking, how did you determine the fault is with the top board? Reason I ask is that I'm still chasing down a problem with my lifeforce doing this (see attached pic), and have been spending most of my time on the bottom board. And for the record, VRAM (and logic chips...

Hi, I've got a 1993 Raiden DX board (not the newer/re-release board), its incredibly clean and been functional for the last year or so I've owned it. Suddenly now when I boot it up, I get a scrambled de-synced mess with no sound. I understand the horizontal hold requirements to get this to...

Well the MCR Switching PS did the trick. I threw out my homemade wiring harness. Although I'm still getting a sizable hum coming from through the +12, I tried putting a 4700uf 25VDC cap across the +12 and Gnd on the switching supply, but it didn't help at all. I think the flurecents are...

Does anyone have info/feedback on QuarterArcade's "MCR Switching PS Adapter"? http://www.quarterarcade.com/Game.aspx/1962 Is it worth $55, or should I just try splicing in my own switched power supply to replace my Spy Hunter's PS PCB?

Thanks for the feedback. I'll try looking deeper into it myself I guess. I'm not an EE major, so not sure how to operate a logic probe or oscilliscope, but I guess I'll have to start learning sometime if I want to keep up with this hobby.

The PCB is Battle Garegga. I belive the problem to be a simple one, where one channel/side from the Yamaha YM2151 appears to not be going into the amp circuit. This channel contains half the background music/instruments and foreground voices in the game. I confirmed this is the problem in...

Anyone know of a tech/shop that can troubleshoot and repair arcade PCBs in the SF Bay Area? Not looking for housecall, just to have the board sent out for repair. (Problem is with sound, missing some music/voices, nothing major.) Thanks. -Dave

Re: J-PAC...Power Supply needed? Just a bump again to see if J-PAC users have this concern with load on the power supply.

Thanks for the info guys. DogP, so a 5ohm resistor should be a good lead for +5? What wattage? And what about the +12? Paige is correct, this is a japanese cab, where the monitor is powered with 100V through the PSU. But I now wonder if Mame people that use a J-Pac have a similar problem...

I'd like to discuss the real issues with running an arcade power supply with no load (or no jamma board). Does this really damage the PSU? Can someone explain why? And would a dummy load (with proper heat sinking) aliviate any possible problems? The application in this case is a video...

Have you hooked up your DC to a cab yet?

Check this out, I wonder if you could power a Naomi via a Dreamcast power supply board. The board easly pops out of the DC, comes with the external plug, and has +5, +12, and +3.3! http://mc.pp.se/dc/psu.html

I had a similar problem with my Joust, and it had nothing to do with the ram or sockets (although it blinked 131 meaning ram error on bank 3 chip 1). Its either bad power or bad connections. First make sure your power supply is accurate on +5. Then check the plastic ribbon cables between your...