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FDP Forum / Fender Amps: Vintage (before 1985) / Trouble identifying my Twin


New Zealand

Geoff Wood
Mar 11th, 2019 10:12 PM   Edit   Profile  

A while ago I bought an old Twin Reverb which was reputed to be a 1978 model. Have given it a total cabinet/grille/shiny-bits overhaul, and it now looks like new.

Started looking for service info, and realised there are many variations and I would like to pin mine down exactly.

It has:
- Silver-face
- 2 x12"
- Serial number(?) "1075050" stamped on chassis rear.
- Master Volume version.
- Tilt legs and stoppers.
- Tube location chart on inside side-wall.
- *NO* Master Vol pull-boost.
- *NO* Hum Balance or Ground Lift switches on back.
- RCA phono sockets on back for Reverb out/in.
- RCA phono sockets for 'Vibrato' and Reverb' footswitch.
- Ch1 has 2 i/p sockets, 'Bright' switch, Vol, Treble, Middle, and Bass controls.
- Ch2 has the same as Ch1 plus Reverb, (Vibrato)Speed, and (Vibrato)Intensity.

Also the foot-switch does turn the 'Vibrato' on and off, but the Reverb one does nothing. Reverb stays on regardless, and no channel switching or anything - Yes, it is wired correctly and footswitch action on/off does appear at the RCA phono plug end of the cable !

Grateful any pointers as to what the full model actually is, where I can get a good overview of how it is supposed to work, and how the Reverb footswitch is intended to work (ie simply Ch2 Reverb on/off, or is it supposed to switch Ch1 to Ch2 for Reverb function ?). And service manual and/or schematic (have found lots of schematics but difficult to relate it to my specific model variation).



(This message was last edited by geoffwood at 12:14 AM, Mar 12th, 2019)

Contributing Member

on the rhine

Mar 13th, 2019 02:57 PM   Edit   Profile  

Hi geoff!

The features you listed are common on all mid/late-70´s Twins. The serial-# is (mostly) useless without the LETTER up front ;-)

You can check the speakers and transformers for their respective date-codes. They will help date the amp - but the serial-# should do fine if you supply us with the letter at the start.

The foot-switch SHOULD turn the reverb and vibrato on/off. If it doesn't there's something wrong with the foot-switch or the circuitry inside the amp - no big deal, I guess.

Its supposed to work and sound like a BIG, FAT Fender-Amp ;-)

cheers - C.


New Zealand

Geoff Wood
Mar 14th, 2019 04:22 AM   Edit   Profile  

Cool - thanks for that. Footswitch good so will delve into the amp. If I can find the correct schematic for my mode - no letter before the 1075050 ;-(

Contributing Member

American Patriot

About as ordinary as you can get.
Mar 14th, 2019 08:34 AM   Edit   Profile  

Sounds like a "Rivera" 1981 or so to me. I had a '77 Twin REverb and it did not have channel switching.

I may have missed it but does you amp have a silver face or black face?


New Zealand

Geoff Wood
Mar 15th, 2019 09:07 PM   Edit   Profile  

Silver face (and now a brand new silver face). Was not suggesting that it did have channel switching, just wondered if a possibility. Satisfied that 'just' and reverb on/off switch function.


Alexandria, Virginia

Mar 17th, 2019 05:24 AM   Edit   Profile  

A 7 numerical digit serial number? I don't think I've seen that before on this period of Fender amps. Possible that "1" is a weak stamping and really an "F". The mid 70's+ original SFs were serial number date coded... I'm leaning towards a "Rivera" like BbendFender mentioned.

A6 + 5-digits – 1976-77

A7 + 5-digits – 1977-78

A8 + 5-digits – 1978-79

A9 + 5-digits – 1979-80

B + 5-digits – 1975, 1976

F9 + 5-digits – 1979-80

F0 + 5-digits – 1980-81

F1 + 5-digits – 1981-82

F2 + 5-digits – 1982-83

F3 + 5-digits – 1983-84

F4 + 5-digits – 1984

(This message was last edited by SS2 at 07:26 AM, Mar 17th, 2019)



Apr 8th, 2019 12:37 PM   Edit   Profile  

Post the tranny and speaker codes. This will also help tell you if things have been replaced.

But yeah, if it's Master Vol, but not push pull, then 78 sounds about right.

It also should have a tail-less FENDER logo but without the "Made in USA" nit that's under the "DER". The Made in USA came about 79 or 80. My early 80 Vibrasonic Reverb has the "Made in USA" script.



now even awesomer
Apr 29th, 2019 10:03 AM   Edit   Profile  

It wont be a Rivera-era (1982-86)... they had "Twin Reverb II" on the front. Also the serial number doesn't make sense for the Rivera-era even if the reported first digit is really a 'F'. Rivera-era s/ns only begin F2, F3 or F4.

FDP Forum / Fender Amps: Vintage (before 1985) / Trouble identifying my Twin

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