I got a Williams Big Guns. I have been doing repairs and maintenance. Got the playfeild 100%. Recapped the power supply and audio board. Upgraded the crap backbox speakers. Still have hum in the speakers but I can live with it even after double checking the grounds in the backbox. While doing all this I knew there was noise associated with the light matrix which I assumed was coming from the speakers. It is not. It is coming from the CPU board, from the actual lamp matrix. What can I do to fix? It is loud enough to hear with the backbox buttoned up.

At some point I would like to switch to LEDs when I get some extra cash.

Thanks,
Tim

I took all the boards mounted to the backbox back wall and took a pencil ereaser to the standoffs and gently on the PCBs. There was no change. All screws are tight. I can hear the noise from CPU board near the lamp matrix. The singing and or high pitched sound is NOT coming thru the speakers.

Here is a short video explaing.

The fast pulsing sound. That is not part of music. Almost sounds like beeping in the video I suppose.

So I took my wife's stethoscope and I think I found what is making the noise. An inductor at L3. Edit - It's definitely the inductor. I can touch and lightly press on it and the sound changes and or stops completely.
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Was going to replace the inductor but shipping was more than the part and I am not ready to buy my next upgrade, LEDs.

Did some googling and it was suggested to use silicone RTV. I did and it calmed it down bit not as much as I wanted. Went to a local electronics supplier and they didn't have the right inductor. Was + .2uH higher, not being an electronics guru I diferred to the guy at the shop. He said if it's working try hot glue even a .2 difference could foul things up.

Peeled of the RTV and snoted up the inductor as nicely as I could. Bingo, it is almost inaudible now. Maybe someone will find my being anal about the extra noise useful.

I still have a hum but I don't know what else to do. I might try unplugging the bottom speaker and see if that helps but I kinda doubt that will make a difference.

ChrisHibler I don't know Jack about electrical design. I can find broke stuff and replace. How do you know when something can be omitted?