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Post subject: Fender Twin Reverb 1977 fix up advice
Posted: Fri Mar 20, 2015 10:20 am
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I recently aquired this Fender Anyone know how to determine the age of the fender? It looks like A7 and 5 digits stamped on the back plate according to this link http://www.superiormusic.com/page195.htm; i think that indicates 1977. I plugged it in the normal channel works the reverb channel makes a nasty whine.

What do you guys recommend i do to refurbish this? I assume these are worth some money i don't want to do anything to hurt its originality

Interesting it has Sunn speakers in it. Looks like some of the tubes are burnt.

Anywhere to find a manual for this?

I am thinking of putting these in it , What do you guys think.


Position Tube price qty ext
power SOVTEK 6L6WXT+ $ 20.00 4 $ 80.00
v1 JJ 12AX7 HG+ $ 15.00 1 $ 15.00
v2 JJ12AX7HG $ 13.00 1 $ 13.00
v3 JAN PHILLIPS NOS 12AT7WC $ 20.00 1 $ 20.00
v4 JJ12AX7HG $ 13.00 1 $ 13.00
v5 JJ12AX7HG $ 13.00 1 $ 13.00
v6 JAN PHILLIPS NOS 12AT7WC $ 20.00 1 $ 20.00
$ 174.00






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Post subject: Re: Fender Twin Reverb 1977 fix up advice
Posted: Fri Mar 20, 2015 4:50 pm
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First thing to do, look at the main filter caps under the doghouse. Replace them, if they are 20-25 years old or show signs of drying out or leakage. Same with the cap(s) in the bias power supply.

Do a thorough visual check of the rest of the circuit. Check for burnt resistors or caps. Bad solder points. Damage in the sockets. Overheated wiring.

If you can post some photos of the circuit board, board under doghouse, bias supply board, transformers, sockets it may help.

BTW... second 6L6GC from the left, in one photo, is shot. White residue = lost vacuum.


Good luck on the restoration! :D


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Post subject: Re: Fender Twin Reverb 1977 fix up advice
Posted: Sat Mar 21, 2015 1:44 am
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BMW2002Ti wrote:
First thing to do, look at the main filter caps under the doghouse. Replace them, if they are 20-25 years old or show signs of drying out or leakage. Same with the cap(s) in the bias power supply.

Do a thorough visual check of the rest of the circuit. Check for burnt resistors or caps. Bad solder points. Damage in the sockets. Overheated wiring.

If you can post some photos of the circuit board, board under doghouse, bias supply board, transformers, sockets it may help.

BTW... second 6L6GC from the left, in one photo, is shot. White residue = lost vacuum.


Good luck on the restoration! :D


+1

As well, it appears that something "cooked off" and dribbled ??? on those speakers. Did it come from that amp or were those corrosive stains on the frames the result of some previous mishap when the speakers were installed elsewhere. That symptom should be investigated thoroughly.

Arjay

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Post subject: Re: Fender Twin Reverb 1977 fix up advice
Posted: Sat Mar 21, 2015 8:06 am
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I'd be a little leery about firing that amp up for any length of time until you've had a qualified tech check out the electrolytics and wiring, as it looks like it might have suffered from neglect-rapid overheating or shorts could occur. New tubes are probably a must, as are most caps.
I have a pair of the Sunn "Guitar Transducer" speaks in a 16ohm, 65W alnico version stuck in a 4x12 cab. Yours look similar, but appear to have ceramic magnets. IIRC, they were manufactured by Eminence for Sunn in the mid-seventies. They are okay speakers, but not my favorites.


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Post subject: Re: Fender Twin Reverb 1977 fix up advice
Posted: Sat Mar 21, 2015 12:05 pm
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BMW2002Ti wrote:
First thing to do, look at the main filter caps under the doghouse. Replace them, if they are 20-25 years old or show signs of drying out or leakage. Same with the cap(s) in the bias power supply.

Do a thorough visual check of the rest of the circuit. Check for burnt resistors or caps. Bad solder points. Damage in the sockets. Overheated wiring.

If you can post some photos of the circuit board, board under doghouse, bias supply board, transformers, sockets it may help.

BTW... second 6L6GC from the left, in one photo, is shot. White residue = lost vacuum.


Good luck on the restoration! :D


Retroverbial wrote:
BMW2002Ti wrote:
First thing to do, look at the main filter caps under the doghouse. Replace them, if they are 20-25 years old or show signs of drying out or leakage. Same with the cap(s) in the bias power supply.

Do a thorough visual check of the rest of the circuit. Check for burnt resistors or caps. Bad solder points. Damage in the sockets. Overheated wiring.

If you can post some photos of the circuit board, board under doghouse, bias supply board, transformers, sockets it may help.

BTW... second 6L6GC from the left, in one photo, is shot. White residue = lost vacuum.


Good luck on the restoration! :D


+1

As well, it appears that something "cooked off" and dribbled ??? on those speakers. Did it come from that amp or were those corrosive stains on the frames the result of some previous mishap when the speakers were installed elsewhere. That symptom should be investigated thoroughly.

Arjay


Thanks Guys for sure leary about plugging this thing in at all let alone for an extended period. When i first looked at the speakers i thought that "cooked off stuff " was bird crap.

I will send some when when i have it apart. I'm going to wait for my buddy who knows what he to look at it . Those caps are a little big for me to mess with without some guidance..

Hopefully it will work out.


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Post subject: Re: Fender Twin Reverb 1977 fix up advice
Posted: Sat Mar 21, 2015 2:38 pm
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I agree with everyone here for sure, get it checked out. I had a 76 that was my main amp for oner 30 years and was the most reliable amp I ever owned. I never used the master volume or pull boost. I just left it that on 10 and pretended it never existed.

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Post subject: Re: Fender Twin Reverb 1977 fix up advice
Posted: Sat Mar 21, 2015 3:39 pm
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63supro wrote:
I never used the master volume or pull boost. I just left it that on 10 and pretended it never existed.


+1

That feature was not properly designed or engineered. It should've been located further "upstream" in the pre-amp, perhaps specific to the vibrato channel only.

Arjay

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Post subject: Re: Fender Twin Reverb 1977 fix up advice
Posted: Sun Apr 12, 2015 7:34 pm
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Well took it to a local amp guy and got it fixed up.......sounds great!
it looks like whatever cooked off on the speakers was not from this amp; maybe the speakers wrere like that when they were put in.

Here is the punch list:

4 new 6L6 power tubes (matched) 70.00
Mid pot & knob (knob you have won’t fit new pot) 9.00
Fuse & fuse cap 5.00
Pilot light bulb 1.00
Re-wire speakers(wire too small & incorrectly wired) 10.00
Clean all pots,jacks, tube sockets

replace filter caps


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Post subject: Re: Fender Twin Reverb 1977 fix up advice
Posted: Sun Apr 12, 2015 11:18 pm
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Congrats, that amp will now be a friend for life.

Perhaps it's time to treat it a cosmetic make-over......?

Rawk on!

8)

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Fender Twin Reverb 1977 fix up advice
Posted: Mon Apr 13, 2015 4:53 am
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Retroverbial wrote:
Congrats, that amp will now be a friend for life.

Perhaps it's time to treat it a cosmetic make-over......?

Rawk on!

8)

Arjay


Yes it could use a little clean up Arjay.........i just wanted to make sure of the electrical first, did'nt want to polish a turd .

Thanks for all the input. This is one loud amp!


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Post subject: Re: Fender Twin Reverb 1977 fix up advice
Posted: Mon Apr 13, 2015 10:13 pm
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MoreGearThanSkill wrote:
Yes it could use a little clean up Arjay.........i just wanted to make sure of the electrical first, did'nt want to polish a turd.


You have your priorities in order, sir.

Just as if it were a classic automobile you intended to restore......have the fundamentals overhauled, then worry about a fresh lacquer paint job, new chrome trim, and period-correct reproduction wheels.

Arjay

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