1978 Preamp Problem with time. Capacitors?

Started by garagebandking41, August 07, 2009, 09:32:37 AM

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garagebandking41

I just finished everything I wanted to do mechanically, and now my preamp is on the fritz.

After about 5 minutes of playing time, some small popping can be heard and the Vibrato seems to be the culprit. The light will stay on when vibrato is off, and if turned on when the speed is under 5 the vibrato will not work, and there's distortion in the sound. However, if the vibrato speed is set about that amount, the vibrato speed is slower for that number, but the full range of speeds is still the same(with just a smaller window to access them, it's "normal".  Another symptom is the power light now pulses with the speed of the vibrato if it is working.

Another thing I'm not quite sure about is that the vibrato seems to be lopsided. There is more left than right, to my perception. And it's not because i sit more to the left, I can hear it in the headphones. Have I gone crazy? Pretty sure It's not a loose solder joint.

I feel like this is a capacitor that is going. hopefully not  and IEC. But since I have a very basic ability to read schematics, and I don't have a multimeter that can read capacitance, I can't really troubleshoot. I've worked on circuit boards through my hobbying around so If its just some parts to fix / resolder I could do that.

Does anyone have a similar problem or knows what I can look at? I've spoken with vintage vibe about a preamp rebuild kit for a 100w preamp so I might be able to just over compensate and replace everything. Since there are no techs in my area...Thanks all.
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