This one is really ****ing me off.

Previous owner had NVRAM installed as it was factory resetting with old RAM. Get it to me, resetting again.

Changed NVRAM with one I had here, toon board out and continuity through board and traces traces and underside (topside traces seem to exclusively go to chip to LEFT.

Sometimes it doesn’t reset if power cycled or turned on later in the day, yet will do if left overnight. Just very intermittent.

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Ahh sorry - it is factory resetting, sometimes it will hold for a few hours, others, it will do it on power cycle.

Bump, I’ve tested continuity and getting good a nice buzz through
NRVRAM socket and traces from it.

Thank you SO much for replying barakandl - the game never does a 5v reset, it’s solid every boot up - just loses factory settings every few power cycles.

So my next test is 5v at p28 and the associated circuit to it?

4.85V solid at D1 and at P28 when powered. Dam it. Was hoping that was it. You said there was a chip that sorts booting up and down. Worth changing that out?

Yeah I have a probe, I will test Pin 37 of the CPU (U4) with the postive on 5 volt TP - and see what comes back. This is mainly a note to myslelf as what to do.

I have tried two kinds of NVRAM in there, this one pictured and the RAMTRON that came with it.

Interestingly, the 'repair' was done, becuase the previous owner was getting resets with a standard RAM in situ, but said the NVRAM installation had resolved it... weird that it would just come back.

Getting a good low then high pulse on pin37, however didn’t get any factory resets through that whole time, annoyingly. So cannot tell if it was a flaky reset I guess, or are these things either consistent or not?

I took a closer picture under the battery area. I can easily buy up the parts and, remove, give it a blast of bleach to neutralise, socket that chip and redo. However is anything in that bank linked to such issues? It seems to go down to C51 and that resistor bank to the left of it.

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Yep sorry, vinegar. Think I have some white vinegar here...

So everyone agrees that is the next step then. Better order some chips

Anyone know if the T74LS14B1 is interchangeable for a standard SN74LS14N at U5?