Hi - the fault is definitely on the CPU as swapped a working board.

When cold - turn on and you get the following effects:

1) Board boots in to attract mode
2) Half the digits on the displays are out
3) Various controlled lamps are out
4) Now and again the Flipper relay K1 buzzes at turn on when cold

1 & 2 above start coming on bit by bit and after a few minutes everything is working 100%

I replaced the caps in the 5v logic section - no difference - and the 5v section test point measures cold 5.15vdc

Nearly all the IC's on the board are on sockets so I have replaced the PIA's and no difference.

I'm not sure if something needs to "charge up" or if something is "dragging down" the power initially. Board is in attract mode though...

Thoughts where to start?

Question - as most of the IC's are socketed - could that be an issue? Could they be drawing slightly more current or something? Although after a few minutes everything is working 100%.