Greetings great community. I.m having some problems debugging a WPC89 MPU.
I.m feeding it on a bench with an external power supply, (that I have used it on lots of other mpus).
The MPU boots perfectly, D19 lit, and go off and D20 start blinking, but after 30 secs or so, D20 goes off and D19 lit and go off and D20 start blinking, and so on and so on.
What I have tried :
Reseated ASIC (with a special tool)
Changed ASIC from other working MPU
Changed U4 from other working MPU
Changed game Rom from other working MPU.
Waited a few minutes, and tested with my fingers each IC on the board, and no one gets hot or warm.
Voltage across C31 is 5,08V all the time.
Any ideas what to try next? I got a logic probe.
Thanx in advance.