Trying to revive an old topic here.

Running in to similar issue with my 79' Stern Dracula. I did a plug and play wire harness to replace all 64 connectors from the MPU to the SP-100 and replaced the connectors from the SB to the Speaker/ETC. Other than sound, the game is working properly. I have been doing some reading on here, but haven't found a good place to start diagnostics to find the issue on the board. Any help would be appreciated.

Side note, a month or so ago I wiggled the cable harness and got sound for a couple hours, but a pop bumper stopped working, then the sound quit and the pop came back, coincidence?

Thanks in advance

Thanks for the quick help, I’m relatively new to ownership so I’ve been investing in tools as I need them. Currently only have a multimeter. Haven’t tested anything yet because i wasn’t sure where to start, what ohms I should be see across what, etc.
I was forced to take a few electrical eng classes in college but have forgotten most of that. Relearning how to read elictrical diagrams would probably be a big help. Guess I should start there.

Sorry I’ve been so slow. Life got busy for a while. Below are results with meter on 20v and picture of meter and board#

I only saw tp 1-7, using tp4 as ground I found
Tp1 - .07
Tp2 - 2.56
Tp3 - 2.58
Tp4 - ground
Tp5 - 2.55
Tp6 - 5.07
Tp7 - 14.4

Thanks for the help

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Per the cable kit I ordered, the grey wire is pin1. Which matches what you stated above.
I decided to reseat the connectors to see if I could get lucky. I was a pin off on the second set of pins on J5 on the main board (marked on drawing). Got a sound that sounded like every tone going off at once, and had 5v across tp1. Put the second 32 pin back to flush and no sound or anything on Tp1

Not sure if any of that means anything but figured I’d report back to the guys who know more than myself.

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I was reseating the connectors to try and get lucky. When I plugged in the second set of 32. I missed the #1 connector, or the number 33 pin for the set of 64.

It made nosies so I checked the voltage and had 5v then noticed I missed a pin and moved it over, lost my 5v

Alright, finally got some time tonight. Pictures below. I notice some blackish looking areas on the back of the sound board, could be the culprit

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Well, we have sound!
I ended up lightly hitting the j5 pins with a wire brush just to knock surface stuff off, and I switched the 1-16 and 17-32 connectors on both boards and when I booted up there was sound!

I appreciate the help with this, hopefully it wasn’t a fluke, I’ll kick power back on tomorrow and see what happens,

Now one pop bumper rebuild (gonna be another first for me) and drac will be %100

Thanks again

Thanks, I tried my best to hit it as lightly as I could, doing some reading on pin connectors i saw stuff opposing really getting into them because of the reason you mentioned above. I haven’t replace a pin header yet, and have only soldered on a board once. But From my short experience so far, I’ll have to figure it out sooner or later haha.