Another A-board failure, assistance requested!

[Kujako]

I had spent some time, socketing and moving around some of the oscillating crystals trying to diagnose a kludged together 12mhz A-board. I had temporarily removed the 68k and z80 crystals from a known working board. I put in some sockets for them, put them back when I was done and everything seemed to work just fine.

Fast forward a couple of days to today... I feel like playing some SF2 WW, plug in the aforementioned CPS1 and get graphics issues. I don't see the usual memory checks, it just goes straight to this. Reseated the B+C boards, same thing. Tried it on the 12mhz board without audio, and it seems to work fine (or as well as anything does on that board). No graphics issues, boots and runs without issue (but no audio, which is not unexpected).

Seems like I managed to kill my good A-board. Unless this could be caused by the crystal failing? Any input or assistance is most welcome.

 

[ekorz]

https://www.arcade-projects.com/thr...le-as-replacing-the-custom.17488/#post-276858

CPS-A-01 custom. They just die

 

[Kujako]

https://www.arcade-projects.com/thr...le-as-replacing-the-custom.17488/#post-276858

CPS-A-01 custom. They just die

Well that blows. I guess it’s just been a bad month for my CPS1 boards. I guess I could try moving the custom chip from the 12mhz board with bad audio to the now failed 10mhz board, but smd soldering is not my strongest skill set. Think I’ll keep trying to fix the Chinese kludge sound subsection on the 12mhz board first. But since I have no idea how it was rebuilt I don’t have high hopes.

 

[YesAffinity]

Well that blows. I guess it’s just been a bad month for my CPS1 boards. I guess I could try moving the custom chip from the 12mhz board with bad audio to the now failed 10mhz board, but smd soldering is not my strongest skill set. Think I’ll keep trying to fix the Chinese kludge sound subsection on the 12mhz board first. But since I have no idea how it was rebuilt I don’t have high hopes.

You might want to check the voltage from your power supply. Could be a root cause here. should be max 5.1v as measured at B board chips.

 

[Kujako]

You might want to check the voltage from your power supply. Could be a root cause here. should be max 5.1v as measured at B board chips.

Voltages should be OK, as the board worked with the same cabinet and super guns a week ago. But I'll give it a check (definitely lower than 5.1v).

 

[Kujako]

You might want to check the voltage from your power supply. Could be a root cause here. should be max 5.1v as measured at B board chips.

Measuring voltage at the PAL pin 20 on the B board, I get exactly 5v on one setup and 4.77v on another (voltage drop due to some stuff between the board and the JAMMA like auto-fire etc). Both within operating range, both producing the same results. It does look like the CPS-A-01 is fubar.