Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Packerswin14 on April 21, 2022, 01:11:41 pm
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Got this Fender Chassis as a "gift". The cabinet and tube chart are long gone. The faceplate and backplate are gone, too, someone brush painted it black and added their own labels.
The PT and OT don't look to be original based on how they are mounted and the cut wires. On the other hand, the wires inside are nicely threaded together. I've never seen a Fender PT on huge standoffs sitting outside the chassis.
The choke appears to be original with a stamped number of 022699.
The serial number on the chassis is A22674, which would indicate a 67 Bandmaster or a 70 Dual Showman Reverb, neither of which makes sense (but we all know how good Fender was with serial numbers).
The person I got it from claimed it was a Dual Showman.
The channel 2 controls are vol, treb, bass, speed and intensity. No presence, no mid control.
There is an outlet on the back.
There are 4 output tubes. Even though a couple of sockets have been changed, it looks like it always had 4, so that should eliminate Bandmasters. I thought maybe someone converted a Bandmaster to 4 6L6's, thus the changes to transformers, but the 2 oldest sockets are next to each other, and the shadows where they put new sockets in indicates that it always had 4, with no hole covers.
The bias pot has a code which dates it to 1966.
Here's another oddity: The resistors on the octal sockets are 1k (Grid) and 560 ohms (Screen).
I looked at the various Showman schems, and with a quick glance, here are the differences I see:
AA270 has different controls on CH 2 and the wrong size cap on the rectifier board.
6G14 has no bias pot, a presence control, 2 caps on the rectifier board, and no outlet
AC568 has no cap on the bias pot, and has a mid control
AA768 looks the closest, but it too has no cap on the bias pot, and has a mid pot.
I appreciate your help, in order to decide my goals for the amp, I need to know what it is first. Plus some of the components are hard to identify from mouse damage. Thanks!
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I'm thinking that's a knockoff copy of a Fender amp. (Maybe ELK?) I've never seen lacing cord in any Fender amp.
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If it were a knockoff, would the caps in the cap pan be the correct brown Mallorys- 2 x 70uf and 3x 20uf? All the caps on the board look correct for a Fender, too. I guess I don't know anything about the knockoffs.
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67 Bandmaster sure seems plausible. The lacing would have been added when converted to 4 output tubes.
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I was wondering if someone added the lacing when they replaced the transformers, too. The work all looks really old, but the thing was full of mouse nest, so everything looks dirty and old.
With some parts from 1966, could it be a Serviceman's amp from the Vietnam era? I know parts can sit around a few years before they get used, but I thought the Elk, etc. amps were later after we had lots of guys over there. Were the counterfeiters stamping the chassis with Fender-looking numbers, and using Fender matching parts? I know the choke could have been swapped later into a clone, but would the makers have used the blue caps, the brown Mallorys, the white Mallory, etc.?
I guess I love a mystery!
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It is a Fender product.
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It is a Fender product.
How can you be so sure?
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Just for fun, here's some more visual evidence to examine
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One more pic
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It is a Fender product.
How can you be so sure?
Eyelet board, type of capacitors.
I could be wrong but I work on many amp close to fender amp like ELK and I never see one close to Fender amps
One thing that is odd and that might belie me is the wires tied together military style. never saw that on Fender amps
So you're right, I should qualify my statement
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The transformers aren't original, you can see the footprint is wrong, and there are shadows where the old feet were that are cleaner and less corroded.
The printing on front and back isn't even, it looks like someone did it with some kind of decal kit or individual letter stencils. The black paint looks very amateur-- badly masked and sprayed on, and was also brushed over on the back (there are brush marks), like they tried one method then switched to the other method. It's such a bad paint job it's hard to believe it was done by any kind of factory.
Were the servicemen amps done one by one? Could they source the same parts as Fender?
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I agree with that. Looks mostly like a Fender except the lace cord. Whoever laced the bundle knew how to properly do it. Looks like a factory job.
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Or parts would have been "taken out" of the Fender factories by employees and sold to very small amp manufacturers/ amps tech ?
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Just found another clue after looking at a photo of a Bandmaster on the web. Two of the 6L6 sockets were masked from the bad paint job-- in the exact shape of those metal hole covers that were used on the Bandmaster to fill in the two holes.
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I do not think the components are much of a clue. I think those caps were standard fare back in the day. But I have read (so it must be true) that Fender and other companies allowed employees to take home 2nd quality parts to do builds, and they were precluded from using faceplates/logos. I say, clean it up and build it up regardless of what it was.
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The board is a perfect match for a '67 Bandmaster, as are the date codes, the chassis, and the choke. I can get a repro faceplate for that, so I think I'll try to put it to an original '67 Bandmaster. The proper transformers aren't even that costly. But first I might finish cleaning out all the mouse residue, popping in some tubes and seeing what it can do.
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that sounds like a good plan. You may want to consider Sluckey's Tremonator circuit. It is easy to do and a big improvement. Fantastic works well on mouse mess IMO.
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It has the Black panel era knobs on it. Look at the 8's. Those were available around 63-67ish. Not sure if any other manufacturer used those specific style knobs. Should have the screw hole at the 10 too.
Just extra info.
-Heath
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All the Mallory caps are date coded 1966. It might be a 1966 Bandmaster.
However, everything over on the power section of the amp appears to have been redone to the point it doesn't even look like "Fender" anymore. All switches except the Ground Switch have been replaced with non-Fender stuff. Dunno what that Black Box with a switch is connected to the footswitch jack (another non-Fender item). Speaker jacks look like they might have been replaced with non-Fender type stuff. Bias/rectifier board is completely non-Fender. The terminal strip for the power transformer is a non-Fender add-on (probably when the PT was replaced, and the two extra sockets were added).
And you're gonna have to strip this thing completely & sandblast it before rebuilding.