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CPS1 - Which are the Sound ROM's?

RealMFnG

RealMFnG

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I have a few dead audio CPS1 boards: SF2CE & SF2HF. Before solder surgery, want to know if the sound ROM's are dead. Which ones are those on the A-board? Any site I can reference this info?
 
Check the mame source code on github. Usually you can figure out what roms hold what data using that.
 
Dead audio is most likely to be a dead Z80 sound CPU, desolder and replace, I replaced mine with a socket to make life easier

Sometimes (extremely rarely) it's something else, 99% chance it's the Z80
 
I changed the z80. No luck. So now it is caps, sound apm, and sound roms. To avoid more soldering, want to check the sound roms first.
 
Is the sound amp working? Does it produce feedback when you touch the pins? If you jack the volume pot all the way up, does it produce feedback?

If there is feedback when you touch the pins or increase volume, the amp is doing its job, otherwise replace it.

If the amp has feedback but no audio comes through, check the op amps for signal coming in and going out (use micro grabbers wired to a pair of cheap headphones).

Roms 18 and 19 are OKI samples, rom 9 is Z80 data for the audio.

Likely your fault is not the caps or roms, but the op amps or amp itself.
 
cpsystem3 said:
Is the sound amp working? Does it produce feedback when you touch the pins? If you jack the volume pot all the way up, does it produce feedback?

If there is feedback when you touch the pins or increase volume, the amp is doing its job, otherwise replace it.

If the amp has feedback but no audio comes through, check the op amps for signal coming in and going out (use micro grabbers wired to a pair of cheap headphones).

Roms 18 and 19 are OKI samples, rom 9 is Z80 data for the audio.

Likely your fault is not the caps or roms, but the op amps or amp itself.
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Thanks man. What you just said is somewhat Greek to me as I am a novice at this. So here is what I have done.
  1. Turned sound pot up down. Nothing.
  2. Replaced sound pot. Turned up/down. Nothing.
  3. Replaced the Z80A with dip socket and new chip. Nothing.
I suppose the next things to do are to check the ROMS, sound amp, caps, in that order. I am thinking the sound roms next because of the ease of doing that due to no soldering. I suppose I can skip that and check the sound amp. So by you saying "If there is feedback when you touch the pins or increase volume, the amp is doing its job, otherwise replace it.", what should I be touching on the sound amp? Just the pins with my bare fingers? What is the "op amp"? What is an "OKI sample"?

Thanks man. I appreciate the guidance.
 
The amp will be on the A board screwed to a metal heatsink on the edge of the board

If you're getting nothing when you turn the volume pot all the way up there's definitely a good chance it's stuffed

The op amp chips send the data from the DACs through to the amp I think? If they're not working you'll get no sound but you should still hear the hum of the speakers being active and perhaps a crackling noise when you fire the board up from the amp powering up

OKI Samples will be the sound (voice I think) samples for the Oki chip that provides the voices, as opposed to the other sounds and music that are produced by other systems on the board.

Are you positive the replacement Z80 was good? Sounds likely it's the amp though if you get nothing at all
 
Ok. I get nothing. No crackling, nothing. I will tackle the sound amp and see how it goes. I have 3 CPS1 boards that have no sound. Had 4. The first one was fixed rather easily with a replaced Z80. Keep you guys posted.
 
Almost always the Z80 is at fault, typically if it's not the Z80 it's the amp, I would doubt very much the ROMs being at fault
 
Testing the B boards on the A board that has sound working effectively test the sound ROMs.
 
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