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Post subject: Twinamp Issues
Posted: Thu Jan 04, 2018 5:17 pm
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Good day,

Can anybody help resolve this issue I am having with my 2004 Fender Twinamp?

The amp work intermittently. I will have a scratchy noise when the amp is freshly played. Then, after 10/15 minutes I will experience a dropout and raspy tone. If I knock the top of the amp, it will cause it to come or go.
(Please excuse my son crying, he was hungry)





Thank You all for any and all help. I am guessing it is a leaking cap somewhere.


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Post subject: Re: Twinamp Issues
Posted: Fri Jan 05, 2018 5:37 pm
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Joined: Wed Aug 26, 2009 4:50 pm
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Location: Denver, CO, USA
The way that sounds, and the way tapping on the cab makes it come and go -- I don't think that's a cap problem

Bad connection -- a solder joint has gone bad, a ribbon cable has gone bad, one of the internal push-on connectors, something like that.

Possibly a tube socket issue. Slim chance that the internal parts of one of the preamp tubes have come loose.

Does it do it on both channels? Both hi/lo power settings?


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Post subject: Re: Twinamp Issues
Posted: Fri Jan 05, 2018 6:07 pm
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Thanks!

It does not do it on the distortion channel.


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Post subject: Re: Twinamp Issues
Posted: Fri Jan 05, 2018 7:11 pm
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That narrows it down quite a bit. Something in the clean channel that isn't shared by the dirty channel.

It's a relatively complex amp that requires a lot of disassembly to get to most of the solder joints.

Are you comfortable working on tube amps, with caps that can store lethal voltages even when the amp is turned off and unplugged?

If not, with those vids and the info you provided, it should be a fairly quick and relatively inexpensive fix for a tech.


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Post subject: Re: Twinamp Issues
Posted: Fri Jan 05, 2018 8:51 pm
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Location: Denver, CO, USA
Oh, one thing that's completely safe to try is to swap some of the preamp tubes around. Swap some of the gain channel tubes for the clean channel tubes to see if the problem moves to the dirty channel. Might just need a new tube.

It's been a long day and I'll be busy tomorrow, but I'll look for a schematic and study it a bit sometime this weekend.


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Post subject: Re: Twinamp Issues
Posted: Fri Jan 05, 2018 9:04 pm
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Hey, A million thanks!


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