Have a Stern Dracula, and it has been playing fine for weeks.

turned it on this morning after i reseated plugs on the sound board (sound was always a bit scratchy) to investigate the sound problem and it would not boot. No LED flashes on the MPU at all.

So i started testing all the test points, and all are good on the rectifier board, solenoid driver board and MPU - althoug pinwiki says MPU TP3 should be 21VDC and mine is 43VDC?

I also replaced the plug and header pins at J5 on the MPU.

My logic says its always the last thing you touched that caused the problem, so i focused on the sound board connectors. I replaced header plug J2 on the sound board. What i discovered is that if i remove J2, the machine leaves the MPU LED solid, however when i replace J2 on the sound board, the LED does not light at all (not even a flicker). Does this indicate a sound board issue - if so, what can i check/test/replace?

I have also put the MPU in paragon, and it boots fine, so i know the issue is NOT the MPU or header pins.

Any help appreciated as this one has me stumped!

Pic attached

20200405_113057 (resized).jpg

Well, got it sorted and this is one of the few times it had nothing to do with the last thing i touched. Found one of the 6821 chips had a hiarline fracture in the leg. Must have been just at the right contact point when i tested the MPU in the other machine!

Repalced it, and all good