Oct 252017
 

Received this faulty Capcom CPS1 A-BOARD, actually the ‘DASH’ revision with a 12MHz oscillator in place of 10MHz one:

Board played with good graphics but sound samples were completely wrong and randomly played, here’s a video made with a Captain Commando B-BOARD/C-BOARD:

PCM samples are played by an OKI ‘MSM6295’ IC which addresses two 1Mbit devices (located on B-BOARD) and reads back their data.Judging from flux residuals the IC was previously reworked on this board as well as other components of audio circuit:

For first I tested all traces to/from it, all was OK.So, most likely, the IC was bad, no wonder since it’s a prone to failure part.I removed it:

Cleaned the PCB from flux and installed the spare:

Time to test:

Board fixed.End of job.

 Posted by at 6:49 pm

  2 Responses to “CPS1 ‘DASH’ A-BOARD repair log”

  1. I have a fairly similar issue with a CPS2 a-board (which obviously has Q-sound). I don’t really understand the Q-sound system – any tips on how to deal with that one? Not sure whether replacing the Q-sound chip itself is the way to go, or if there’s another chip which would be more likely the culprit. Cheers!

  2. I’m not really familiar with CPS2 but you could try to reflow the QSOUND chip which is the DL-1425 in PLCC84 package.