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Fixing Yamaha MW-10 desk....oscillation problem
I am attempting to repair a yamaha MW-10 mixing desk. When I got it, there was no functioning output. Using a signal generator and an automotive oscilloscope (just a modified tv found cheap, i need to upgrade....) and the service manual I traced the fault to a bad IC, the last before output, and replaced it with the right part from the factory.
Now it does amplify, and all channels are working, but there is an oscillation of .5-1 Hz that appears when the return or 2track in pots are turned up. It seems that all the areas the problem signal is share a particular ground line, I am thinking it is a faulty cap on that line, but my basic knowledge of electronics isn't quite enough at the moment.
Would a faulty cap somewhere on a ground path cause this? How does one test caps in circuit? Any other thoughts on what could cause this?
Now it does amplify, and all channels are working, but there is an oscillation of .5-1 Hz that appears when the return or 2track in pots are turned up. It seems that all the areas the problem signal is share a particular ground line, I am thinking it is a faulty cap on that line, but my basic knowledge of electronics isn't quite enough at the moment.
Would a faulty cap somewhere on a ground path cause this? How does one test caps in circuit? Any other thoughts on what could cause this?