D/E cpu board problem

[paddythegreek]

Got a mates Maverick cpu board on the bench with just 5v and earth to run it. It boots up exactly as it should but as soon as the blanking led lights the relay clicks in and stays in TILL after about 12 seconds the blanking led goes out and the relay drops out. 1-2 seconds later the blanking leds back on, the relay clicks in and we keep repeating this scenario again and again etc. When the blanking led goes out the pia led don’t come on which makes me think it’s a blanking fault and not a reset one.
Any ideas guys. Ken

 

[CHRIS B PINBALLS]

Have you put an nv ram in it

 

[paddythegreek]

Nope??

 

[paddythegreek]

Update. Sorted. For anyone interested it was the 6821 chip at 11b. Now boots with no resets or relay pulling in .