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Post subject: Need help to solve a problem--
Posted: Sun Oct 04, 2009 1:13 pm
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I have a '74 Super Reverb. I bought it (used of course) in 1994.
It has always had a problem though. Without any pattern and at different
residencies (states,houses,apts,countries), cords, surge compressors. I have taken it to many Fender repair shops in different states, and no one can replicate what it does for me at home. What does it do? It loses volume, maybe an 80% decrease. I will be playing and all of a sudden, bam, the volume just
decreases. I turn the standby switch on then off again and the volume
always returns...until the next time it does it.
Any ideas??? Is this common???


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Post subject: Re: Need help to solve a problem--
Posted: Sun Oct 04, 2009 1:50 pm
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crystal_the_pistol wrote:
I have a '74 Super Reverb. I bought it (used of course) in 1994.
It has always had a problem though. Without any pattern and at different
residencies (states,houses,apts,countries), cords, surge compressors. I have taken it to many Fender repair shops in different states, and no one can replicate what it does for me at home. What does it do? It loses volume, maybe an 80% decrease. I will be playing and all of a sudden, bam, the volume just
decreases. I turn the standby switch on then off again and the volume
always returns...until the next time it does it.
Any ideas??? Is this common???


Sounds like a capacitor leakage problem. As long as the capacitor is cool, it wonlt leak and the power is at normal operating parameters. Once the capacitor heats up, it begins to leak and your power starts petering down.

Yes, this is a common occurence as typical capacitance life is only good for about 10 years from the time they are put in service.

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Post subject: Re: Need help to solve a problem--
Posted: Sun Oct 04, 2009 2:13 pm
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Hey thanks! awesome! Is it something that a novice can do?


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Post subject: Re: Need help to solve a problem--
Posted: Sun Oct 04, 2009 3:59 pm
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crystal_the_pistol wrote:
Hey thanks! awesome! Is it something that a novice can do?


Glad to help.

No. Among other concerns, there's dangerous stored juice in an amp just waiting to seriously zap you.

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Post subject:
Posted: Sun Oct 04, 2009 6:27 pm
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74' silverface I would look at the preamp bypass caps, May be going and causing the bias to change rapidly and volume drop off suddenly when they open up. Thats just a start, 74 thats before they added the distorion switch right?
Not in my office right now so I don't have schematic.

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Post subject:
Posted: Sun Nov 01, 2009 4:02 pm
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If you have to ask, the answer is definitely no. Lots of voltage lurking around in there and can be very dangerous - definitely not something for a novice to attempt.

I can change my own preamp tubes and speakers, but anything more than that I go to my great amp tech in Redondo and he sets it right.


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