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Post subject: Twin Reverb Problem
Posted: Sat Aug 28, 2010 7:00 pm
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I picked up a 1990 Twin Reverb today at GC - so I still have my 30 days ticking. It played great while I was trying it out at the store (don't they all?). After I got home and set it up and started playing, I noticed the volume seemed to phase in and out. Basically, the volume would be normal then drop down very noticeably but not off and then go back up. It would keep doing this. I used both inputs on the Vibrato Channel, and it happened on both. I haven't tried any extensive playing on the Normal Channel. The amp was recently retubed and rebiased so that shouldn't be a problem.

You guys think I should hit the tube sockets with some Deoxit? What about the pots? Any other thoughts about what could be causing this? I don't want to give up the amp, but I'll take it back for a different Fender amp if necessary. Thanks.


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Posted: Sun Aug 29, 2010 12:34 am
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Surging volume can be a symptom of tired power tubes and/or incorrect idle bias.

Take it back to the store and tell them to fix it or keep it.

Best of luck, HTH

Arjay

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Posted: Sun Aug 29, 2010 5:45 am
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Retroverbial wrote:
Take it back to the store and tell them to fix it or keep it.


Thanks Arjay. That is not the part that I really wanted to hear, but that will most likely be the end result.


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Posted: Sun Aug 29, 2010 9:04 am
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I played this thing a little more this morning and tried it on both channels. The problem is there on both channels. It actually sounds like the speakers are blown. There is serious drop in volume down to almost nothing and it's real crackly and static-sounding. Blown speakers?

I hate to say it that I have never owned an amp long enough to know what a blown speaker sounds like. :oops:


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Posted: Sun Aug 29, 2010 9:43 am
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Personnally I don't think about the speaker; As Retroverbial said take it to the dealer for warranty. :wink:

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Posted: Sun Aug 29, 2010 12:46 pm
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My guess would be a faulty phase inverter and/or faulty power tubes. But yeah, try the Deoxit first. At this age of the amp, the power supply caps and the bias circuit components would also be a consideration. Art

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