Fender AB1263 Tremolux schematic needed

[Matthews Guitars]

I can find many versions of the Tremolux schematic and layout. but I've found NO luck in trying to find anything referencing the AB1263 design.

My Tremolux has AB1263 stamped on it in two separate locations.

It's a brownface made in 1963.

I've been using the 6G9-B schematic and layout diagram to rebuild my amp. (I got it in mostly disassembled shape, from my amp tech friend who was
going to do something to it, but died before he got very far.)

The 6G9-B schematic and layout are close enough. Or almost. The only difference I've actually noted is that the 6G9-B circuit doesn't have a standby switch.

I'd like to get the AB1263 schematic and layout, just in case anybody does have it.

[pdf64]

I recall my elder brother buying a blonde Tremolux, about 40 odd years ago. I don’t remember the valve chart code, but I think the phase splitter was listed as a 12AX7, though it was the AA763 circuit as far as I could tell (including the standby).

[Matthews Guitars]

This one is a match to the 6G9-B, or almost. It's MUCH closer than the AB763 schematic. But it's an AB1263 by the chassis stamps and that's the schematic and layout I need.

[dgrainger]

Isn't that a date code or order number type thing (not quite as specific as a serial number) rather than a circuit designation?

[sluckey]

But it's an AB1263 by the chassis stamps...

I've never seen any old Fender amp with the model number stamped on the chassis. And I've never heard of a "AB1263" model. I suspect that stamp means something else.

Why don't you draw a schematic and post for us to try to help you sort this?

[Stevem]

What are the date codes on the transformers and some of the pots if there original?

I have never heard of a AB designated amp with a 4 digit date code that was not in the Blackface era!

I would say the starting digit of 1 is a printing mistake and Fender use used those cabinet stickers anyway as they have been known to do.

You may have a preproduction transition amp between Blond and the blackface era as Leo was known to sell anything as long as his circuit development needs where over it worked!

If your just rebuilding it to sell it then don’t be so concerned about rebuilding accuracy because if you and everyone here can’t nail down what the circuit was originally, then how could a buyer deduce such?

[martin manning]

Are you sure you are not seeing a rubber stamp artifact that makes AB763 look like AB1263? The AB763 Tremolux schematic is dated C-FD, which is 4-64.

[Matthews Guitars]

When I get back down to the shop I'll take a few photos that show BOTH places on the chassis where AB1263 is stamped in black ink.

It appears to be a 6G9-B layout with an added standby switch.

It has a brown faceplate, (brown back plate, too) white cupcake knobs, and the headshell it came with, which appears to be in original Fender tolex, is done in black tolex.

I can not tell you if the headshell is original to this amp. Only that it came with it as I received it, and it fits.

Does it have a tube chart in it? Honestly I wish I'd paid attention but once I took it out of the headshell to start evaluating it, I've never bothered to look. I'll do that on my next trip to the workshop. That tube chart should identify the circuit, but even then, with no guarantee that the headshell is original to this amp, it won't be conclusive proof.

Mods: The only evidence of past modifications is two 1/4" holes drilled in the back panel which would be the right size for mini toggle switches.

I'll also check out the transformers by part number to see if they are original. In appearance they seem to have about as much age on them as the chassis does,
and I don't see any extra holes from mounting a transformer with a different mounting pattern.

[Matthews Guitars]

Incidentally this is a 6L6/octal socket power tube version, not a 6BQ5/EL84 chassis.

[Matthews Guitars]

Here are two photos of the amp in question. Not the best quality but I'm not looking for component-by-component analysis at this time.

I've done a lot more to rebuild the amp since these photos were taken. Right now I'm waiting for my tapped treble pots to arrive so I can install them,
and after that it's just a matter of finishing up about a dozen connections and then test. After successful testing it's time to tidy up the wiring which
means replacing some wiring with vintage correct cloth insulated wire. Since I have some, why not use it?

For this amp I dipped into my stash of blue molded capacitors. Why not? They're good, they measure good, and in fact I've never found one that was actually bad.

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[martin manning]

I believe that stamp is the assembler letter code (B) and the date, 12th week of 1963. I'd guess the circuit is AA763.

[Matthews Guitars]

I seem to have lost a reply I posted.

I checked all the layout sheets, AA763, AB763, 6G9-A, 6G9-B, and it's clear that the eyelet and hole pattern on the board are not even close to the 763 layouts. Differences are numerous,
and the first one to catch my eye is that the 763 layouts use a "bug" neon lamp and photocell package. There's no provision on the board for that. Lots of other details say it's a 6G9 layout,
too.

Aside from the polarity switch issue, it's a perfect match to 6G9-B. So I speculate that it's a late 6G9-B with added polarity switch and there is no published exact matching document, for
this hypothetical 6G9-C circuit.

The chassis also does not have a bias control, so that's pretty conclusive in favor of the 6G9 circuits.

It's a brownface chassis, with front and back plates being brown finish, but the head cabinet that it was in (which may not be original to this chassis) is covered in regular black tolex, and it appears to be original, not a recover. Don't ask me what the tube chart says, I don't remember what it said when I looked at it last...some time ago.

I'll have to go back to the shop to get a photo of that.

[martin manning]

You photo looks like a 6G9-B board in AA763 chassis. You have the ground switch, standby switch, and bias trim pot.

[Matthews Guitars]

As far as I know that board is original to this chassis. So...still thinking it might be transitional. Late 6G9-B/early AA763.

Does that seem possible? Would Fender have released an amp that was transitional between old and new versions?

[martin manning]

Yes, there are other examples of them doing just that.