So, I am stumped on a -35 Bally that is on my test bench rig. I have installed all new sockets, and jumped the board to use 2532 EPROMS, just like two others I have on the bench. I have confirmed all socketed chips are good, including EPROMS. I have 3 boards set up for 2532 Eight Ball Deluxe EPROMS and two work. This 3rd one does not.

Upon power up, the MPU LED flashes once, but every once in a while (10% of the time), it flashes the first flash over and over and over and over... forever. I know it's the first flash because the timing between the flashes is different for flashes 2 through 6.

I am aware that ONLY one flash (after the initial flicker that I AM getting) means that the 6810 RAM is likely failing. I checked the socket, even pulled it and replaced it to check the traces under it. All are good. RAM and all other chips are a known good set. Everything around the 6810 looks ok, I toned out every trace from and to the 6810.

I've not seen a board like this that only flashes once where the 6810 RAM is not the culprit.

There was minor corrosion but it has been cleaned and the sockets have been replaced. Besides, I am certain the rest section is working because it is consistently getting it's first flash. I have a basic logic probe but really don't know where to look next with the probe. ???

I think I tested pin 40 of the 6800 CPU and was getting 4.2 volts.

You can't run a 6802 CPU without a 6810 RAM in a -35 Bally MPU can you?

Yes, even though it was a known good set of ICs and EPROMS, I did swap the 6800 to double check. I also double checked the CPU socket.

EPROMS select ICs... Not certain what ICs you mean. I'm using U2 and U6 if that helps.

I did swap the 5101 socket with a new one as well. I do that on every single board by default, even if it boots.

That’s what I thought was happening but I have checked the chip and socket so I’m lost on what to do.

Ok, I have things to check, I will report back here with my findings. Resistors, caps, and lines back to the CPU.

Update: it’s fixed. BarKandl, you are the man! Here’s the trace that was repaired.

E17 to the pin with the black mark on the 6810.

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