Got a DE Rottendog MPU that was in a Playboy machine – I assumed it was working, but looks like its not the case. The Playboy is cactus, so I took the board out of there to repair another guys Hook that had battery leakage. It didn’t work – the PIA and 5V lights stay on, and blanking never goes on, PIA never goes off.

The machine upon power up says “Hook” 3 times, but nothing appears on the display

I have:

Put new sockets in Rom/RAM/CPU

Checked all 6821’s in my Quicksilver, and 1 didn’t pass self test, so I replaced it

All voltages are good.

I did see the signal at the 555 chip is low at pin 3, when it should be high, not low. I also saw some info stating that Pin4 of 11B should be high with a logic probe – which it is.

Can anyone offer any advice on anything else to check?

I have also verified that jumper J5 is in, which is the appropriate setting for a 512k ROM in U27 (and verified that the game ROM is a 512 chip)

Problem solved. The board was supplied with a dodgy 6802 at u3, then the one i used (that i thought worked) was also dodgy.

After trying a 3rd time (and many other things), with another new 6802, everything worked!