CPS-1 Sound Issue

[GeorgeSpinner]

I have a CPS-1 with bad sound.

I say "bad sound" instead of "no sound", because it does play some sounds nice and clear.

It does not play any music.

The A PCB is the 89626A-4 12 mhz DASH model.

The B PCB is a Daimakaimura (Japanese Ghouls n Ghosts) reproduction.

In the test menu, it will play some of the sound effects, but none of the music.

No sound is made when inserting a credit.

When the opening scene plays out (after pressing start), only 2 sounds are played (no music), when the 2 characters are cut down by the demon.

When the game begins, 1 sound is made. That sound kind of echoes and then there is nothing but silence until the power is cycled.

I have created a video that demonstrates the issues I am describing: https://youtu.be/f1tHsWFhHc0

Does anyone know what may cause this issue?

My searches have revealed it could be the z80 but I do not want to just start replacing parts (although that may be required).

Thanks for your time.

 

[AlxUnderBase]

Maybe that eeprom who keeps sound on it is faulty ... can you write that bin on a new 27C010 again ? What B board is yours ? Mine is ... 90629B-2

 

[GeorgeSpinner]

Thanks for the reply.

I apologize for posting in the wrong section. I do not know how I did not see the CPS1 section. A very bad first impression on my part.

I did not write the roms and no longer have the hardware to do so.

I should add that the game was working perfectly for about 35-40 minutes (level 5 for the 2nd time) and then a loud noise was emitted. After that, the sound cut out and it has been in the state I originally described.

I removed all the roms and cleaned all the sockets today. Still the same.

B Board is 91634B-2.

 

[GeorgeSpinner]

I created a thread in the correct location. Apologies.

 

[AlxUnderBase]

Thanks for the reply.

I apologize for posting in the wrong section. I do not know how I did not see the CPS1 section. A very bad first impression on my part.

I did not write the roms and no longer have the hardware to do so.

I should add that the game was working perfectly for about 35-40 minutes (level 5 for the 2nd time) and then a loud noise was emitted. After that, the sound cut out and it has been in the state I originally described.

I removed all the roms and cleaned all the sockets today. Still the same.

B Board is 91634B-2.

This is the 27c1001 or 27c010 you should check. If not , maybe somebody with repairs experience knows what to tell you But , its fixable

 

[ic3b4ll]

Test the ROMs but I'm willing to bet it's the YM2151 or something connected to it. If the EPROMs were bad you'd likely get no sound or corrupted samples. Music in the CPS1 is handled by the YM2151, an FM synthesis chip. I don't know how it's mixed with the effects (handled by the OKI... something) but it's likely done in the analog domain using op amps. So, erm, it's complicated. Get a logic probe if you can it will help immensely.