Centipede board help

[Hawkypro]

Guys,

Ive got a centipede board that has a humming sound coming from the board. Ive done the ARII upgrade and replaced the big blue cap ect... and replaced the pokey chip. I know its coming from the board because I connected a speaker to the speaker output on the edge connector and still get the hum. I can hear the game sounds if I listen closely. If you guys have any suggestions let me know.

Thanks,

Hawkypro

[Level42]

Replace the LM324. It often dies. It did on my board too. Replaced it and works great.

[Hawkypro]

Level42,

Thanks for the info, and I hope my machine looks like yours when im done restoring it. I will look at LM324 and let you know what I get. This problem has had me stumped for a while.


Update: Replaced LM324 and still have the problem, 

Hawkypro

[Level42]

Well that's mostly all you can do on the game-board. You mention you did the AR=II upgrade. Did you just do the cap-kit or more ? The TDA on the AR-II is the next step where the audio gets amplified so that could be gone too.

[tafische]

Have you checked the volume control knob?  I have a new Centipede machine and I have to "work" the knob a little bit or I get some hum. 

[Hawkypro]

Level42,

Yes, Ive done more than just the caps on the AR=II  so im still troubleshooting the problem.


Tafische,

Yeah, ive done that with volume knob.

thanks for the input so far from the both of you guys.

Hawkypro