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Post subject: Bassman Amp, 1967?
Posted: Wed May 18, 2011 1:48 pm
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i have a bassman amp chassis only, missing the power transformer and tubes.
I'd like to get this thing working, but not sure what transformer or tubes it needs.
It's stamped inside the chassis "T383967" and "W39". The choke is "022699", "606-7-23".
The output is "022871", "606730". I think the second of these numbers are date codes.
What I don't know is the model # of the amp. Are the 5881 tubes interchangeable with the 6L6GC's? And the pre-amp tubes, 7025? 12ax7? 12at7?

Any help or suggestions would be helpful.

Thanks, Mike Williams


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Post subject: Re: Bassman Amp, 1967?
Posted: Wed May 18, 2011 2:12 pm
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From the EIA codes on the remaining trannies, it does appear your amp is the AB165 circuit. Here's the schematic for that specific chassis......

http://www.ampwares.com/schematics/bassman_ab165.pdf

You'll note on it that the part numbers for the transformers are formatted as the old "Fender Electric Instruments Co." designations. The CBS-era Fender part number for the Bassman power tranny is 022814. The other numbers stamped on the trannies (ie: 606-XXX) indicate the manufacturer (in this case Woodward-Schumacher) and the date that the component was made.

Personally I would not substitute 5881's for the specified 6L6GC's, at least not using vintage NOS tubes. The older 5881's shouldn't be used in applications where the plate voltages exceed 430VDC. YMMV

HTH and welcome to the forum.

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: Bassman Amp, 1967?
Posted: Wed May 18, 2011 4:19 pm
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Hey, thanks Arjay! I prefer the 6L6GC's, but wasn't sure 'cause some Bassman amps call for the 5881's. As for the pre-amp tubes, I think I have a 12AT7 (far left with tubes facing me) then two 7025's, then a 12AX7A. will this be O.K. with the tranny you mentioned, or do I need three 7025s, or can I use three 12AX7's? I have a couple Fender groove tube 12AX7's and the sovtek stamp is 7025. Thanks again, Mike


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Post subject: Re: Bassman Amp, 1967?
Posted: Wed May 18, 2011 4:38 pm
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Your current pre-amp tube array should be fine, Mike.

You can use a number of different subminiatures in positions V1 through V3 (7025, 12AX7, 12AX7A, 5751, etc) but most vintage Fenders work best with a 12AT7 in V4, which is the phase-inverter stage.

AFAIK, the only Bassman's to use 5881's are the tweed 5F6 4 x 10 models (plus the re-issues) and the early blonde 6G6 piggybacks.

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: Bassman Amp, 1967?
Posted: Thu May 19, 2011 9:25 am
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Great Arjay, thanks again. As for the 5881's, I have a CD of schematics & layout diagrams, and not being familiar with the model #'s didn't know which was which.
Can't wait to get the tranny and get this thing to work again, but I will have to for a little while. Right now I'm working on a friend's '64 Showman amp and cab. Pretty sure of the date on this one, as it's stamped on the back of the chassis. April 28, 1964. Nothing electric, just cosmetic. Unfortunately someone painted the tolex white, and the grill cloth gray. Replacing the tolex, grill cloth, corners and handles should make it look as sweet as it sounds. Anyway, I really apreciate your help. I'll let you know how this stuff turns out............Mike


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Post subject: Re: Bassman Amp, 1967?
Posted: Thu May 19, 2011 9:38 am
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Michael C. Williams wrote:
Right now I'm working on a friend's '64 Showman amp and cab. Pretty sure of the date on this one, as it's stamped on the back of the chassis. April 28, 1964. Nothing electric, just cosmetic. Unfortunately someone painted the tolex white, and the grill cloth gray. Replacing the tolex, grill cloth, corners and handles should make it look as sweet as it sounds.


Ouch!

I hate it whenever somebody does a "Krylon dye job" on a Fender amp.

I did a Showman restoration last summer -- the cab was a '65 with a chronic case of road rash and the head was a '68 silverface in even rougher shape. All new Tolex, grill cloth, hardware, repro black faceplate and knobs got it looking like this......

Image

An all-new set of NOS glass, some TLC within the chassis, plus a pair of freshly-reconed D130Fs completed the restoration.

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: Bassman Amp, 1967?
Posted: Thu May 19, 2011 9:05 pm
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Wow Arjay. that is sweet! The '64 is getting rough blonde tolex and wheat grill cloth. The original brown faceplate is still in good shape. Hope it comes out close to as good as that one!


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Post subject: Re: Bassman Amp, 1967?
Posted: Thu May 19, 2011 10:30 pm
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PM inbound, Mike!

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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