Hi everyone-

I'm slowly weeding out all of the gremlins in my Flash. In the recent weeks, I've done a LOT of fixes and upgrades to the game, but unfortunately I still can't get it to run stable. Here's a rundown of what I've done and where I'm at:

Upgrades/Repairs-
Rebuilt PSU with all new caps, diodes and 5v/12v pin header & connector (also dropped displays to 91v)

Rebuilt MPU- new rom, ram and cpu sockets. Installed new ram, cpu and freshly programmed green rom set. Replaced 40 way connector. Replaced all pin headers, replaced 5v/12v input connector. Replaced 5v regulator.

Rebuilt Driver- All pin headers replaced. 5v filter cap replaced. 5v and switch matrix connectors replaced. 40 way connector replaced. Lamp matrix upgraded to MOSFET drivers and 0ohm resistors

Sound board- (unrelated to resets but I'll list my fixes). New caps all around. New buffer IC's installed (previously played incorrect sound effects).

Current Problem Description / The game's current state-
The game will boot up perfectly 100% of the time. I am able to leave it in attract mode without crashes or resets. I am able to run all diagnostic tests with no crashes or resets. All sollenoids and switches fire properly from diagnostics. All lamps flash correctly both in attract and diagnostics mode. When I start a game, I can usually get through ball #1 just fine, sometimes not. Just about every single time, the game crashes on or around when I get to ball #2. When it crashes, it appears to be in two parts. First, the lamp matrix will start flashing every lamp on/off (just like diagnostics test), then after a while the lamps will all turn off and displays will go blank. When this happens, flippers slingshots and jet bumpers are still energized. I need to physically turn the machine off then back on to get it "running" again. It should also be noted that Leon's test rom passes all tests when bench booted with an auxillary PSU. Also, up until last night, there was (accidently) 35v DC running into Column #3 of the switch matrix. Is is possible it caused damage to my switch PIA where it still functions (until its under game-load and breaks down)?

Does anybody have any ideas on where to start poking around? It seems as though the game crashes when "under load" (during a game). I haven't isolated it to a specific sollenoid, switch or combination there of. It seems to crash at random.

Gut tells me to- check all coil diodes for shorts and suspect the switch matrix PIA. Would love to hear some other suggestions...

Thanks for any help guys

Thanks for the tip Bob, maybe that will get me in the right direction!

I ran all of Leon's test-rom tests, and they all passed. I also ran all of the Williams Diagnostics, and they passed. I have however not tried Andre's test rom... i recall reading that its able to (sometimes) detect faults Leon's can not? Looks like I'll be trying that next, thanks!

Bump, help please

Didn't get around to trying Andre's test rom quite yet. I will observe pin 37 and report back.

Yes, I checked continuity for all the address and data lines, and they check out. I'll try the back-box fan and see if that helps.

Also worth noting, the MPU sometimes gets hot to the touch after a lockup.

Thanks!

PS- The thread on RGP with this same issue is mine, I noticed you posted there as well

I checked for shorts on the sockets already (ie pin 3 to 4, 4 to 5 etc). I will check again

Ahh good call, I was just checking the integrety of the traces with no chip inserted. I guess its possible the force of a chip could cause a flaky connection to let go.