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Post subject: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Wed Mar 27, 2013 11:53 am
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Hi, I have what I believe to be an earlier (17-18th week) 1968 Fender Twin Reverb AB763 "Vintage" Electric Amplifier Combo that's been in my home stored away since the 1980's I've spent quite a bit of time recently getting all the info from some sites around the net I can about these amps in general like production dates, serial production numbers, ink stamped date codes, how to decipher them and so forth.

I'd like to know here on the actual Fender forum is, is this actually a May 1968 silver face twin with blackface circuitry - AB763 model.

Is there anyone here that would look at my pictures and numbers and assist me in this?

Thanks,
Dave


Last edited by Time Warp on Wed Mar 27, 2013 2:31 pm, edited 1 time in total.

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Post subject: Re: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Wed Mar 27, 2013 1:24 pm
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Hi there, Dave. Go ahead and post the photos, especially chassis interior shots and transformer serial or part number shots. I'm sure you'll get an in-depth response!!! Art

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Post subject: Re: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Wed Mar 27, 2013 1:38 pm
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Ok Thanks, Be great to learn anything. Here's some I've taken on PhotoBucket if I can.

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Post subject: Re: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Wed Mar 27, 2013 3:56 pm
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From the pics everything (black lines on face plate, codes on transformers, speaker codes, etc) lines up with mid year 68 and maybe as early as May. Speakers show 16the week of 68, so if original, they would have been made shipped and popped in your amp pretty darn quick to make may but not out of the realm of possible for sure. I think you can safely say mid year 68 for sure.

A guy named Retroverbial will probably be by soon and give you a more difinitive answer, but all looks right and good to me. He might be able to tell you the exact circuit too, it may not be an AB763...Tube charts are notorious for not being correct with regards to which circuit you actually have.

Nice clean amp by the way! Thanks for the amp porn!

FWIW

T2

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Post subject: Re: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Wed Mar 27, 2013 4:23 pm
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T2Stratman wrote:
Nice clean amp by the way! Thanks for the amp porn!


haha, glad to show it and thank you for the feedback. It sounds like everything including speakers date from week 16, 17 &18.

Another thing I was also unclear on was the date ink stamped on the inside of the chassis because it looked like to me it was T161868 but the 1st (8) looks a bit like a (3) which would make that date 4 weeks from the date ink stamped on the outside of the chassis (F061768)

Thanks also for the speaker date, I hadn't dated the speakers.


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Post subject: Re: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Wed Mar 27, 2013 4:58 pm
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Tentatively, I'm going to pronounce the circuit as an AB763 since it lacks the shielded pre-amp wiring common to the subsequent AC568 revision. A nice tight shot of the underside of the power-tube sockets would allow me to confirm my hypothesis.

Wonder where the grill logo got off to......?

:mrgreen:

Arjay

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Post subject: Re: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Wed Mar 27, 2013 5:02 pm
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Yep, Dave. AB763 circuit for sure!!! Definately worth a thorough maintenance check-up. It's a keeper!!! IMO, Art

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Post subject: Re: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Wed Mar 27, 2013 6:02 pm
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Guys, sorry to be a stick in the mud, but those grid-to-ground resistors (supposedly 220k-ohms) and the ones that feed the PI anodes (82K and 100K-ohm) don't "appear" to be correct. At least on my computer screen. A closeup of this area would be nice.

We are talking the resistors in V-shaped networks aroudn the 0,1mfd coupling caps from the 12AT7 to the 6L6GCs.

http://www.webphix.com/schematic%20heav ... _schem.pdf

Thannks!

:mrgreen:


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Post subject: Re: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Wed Mar 27, 2013 6:23 pm
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aclempoppi wrote:
Yep, Dave. AB763 circuit for sure!!! Definately worth a thorough maintenance check-up. It's a keeper!!! IMO, Art


Thanks Art. I'm very happy to have learned that it's a AB763 and a keeper but wanted this info to help me better market it. I was a little uncomfortable with my piecing the puzzle together myself.
I feel better having it confirmed here.

Retroverbial wrote:
A nice tight shot of the underside of the power-tube sockets would allow me to confirm my hypothesis.

Wonder where the grill logo got off to......?

:mrgreen:

Arjay


Thank you Retroverbial. Are you saying I should take a tube out and take a picture of the area the tube goes into on the underside? I have no idea where that logo is. It could be around here somewhere.

BMW2002Ti wrote:
Guys, sorry to be a stick in the mud, but those grid-to-ground resistors (supposedly 220k-ohms) and the ones that feed the PI anodes (82K and 100K-ohm) don't "appear" to be correct. At least on my computer screen. A closeup of this area would be nice.

We are talking the resistors in V-shaped networks aroudn the 0,1mfd coupling caps from the 12AT7 to the 6L6GCs.

http://www.webphix.com/schematic%20heav ... _schem.pdf

Thannks!

:mrgreen:


Hi BMW2002Ti, I'm not familiar with the precise area your concerned with and don't read schematics. I'll be happy to take the picture If there's any you can assist my little brain in understanding where exactly to pinpoint.

I may have to get to it tomorrow, almost 10pm here.

Thanks again guys,
Dave.


Last edited by Time Warp on Wed Mar 27, 2013 6:34 pm, edited 1 time in total.

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Post subject: Re: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Wed Mar 27, 2013 6:27 pm
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I'd like to see the inside of the chassis -- specifically the area of the power-tube sockets.

Arjay

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Post subject: Re: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Wed Mar 27, 2013 7:28 pm
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Beemer and Arjay, I think the color on the computer is deceiving! Take a close look at the solder joints. I see typical Fullerton work and no signs of resoldering. JMHO, Art

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Post subject: Re: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Thu Mar 28, 2013 6:30 am
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Retroverbial wrote:
I'd like to see the inside of the chassis -- specifically the area of the power-tube sockets.
Arjay


Gotcha...Here's inside the chassis in the power-tube socket area.

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Post subject: Re: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Thu Mar 28, 2013 5:07 pm
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I was just offered $900 but didn't sell. Do you think It would sell for $1500 on ebay? I was actually hoping closer to $2000 but really have no idea. Seems difficult finding this exact design. I saw a pretty nice one sell there for just under 1200 but it was dirty looking & had a lot more scratches, some pretty big scratches I would consider tears.


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Post subject: Re: Early 1968 Twin with Blackface Circuitry (AB763)
Posted: Thu Mar 28, 2013 6:07 pm
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I've seen them *listed* for $1500.

There seem to be few takers though.

Arjay

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