Rare untouched beauty: 1965 Fender Bassman with the transitional AA165 circuit.

Cap job and power cord replacement for a pristine 1965 Fender Bassman. Alas, what looked like the rare AA864 circuit turns out to be the short-lived transitional AA165 circuit.

[@thatampguy]

Nice channel. I probably restore 4-6 of those annually and I've never seen those blue filter caps before. I'm usually treated to those sweet gold GE caps on occasion. What a find! Happy holidays!

[@Kilgore40]

Thanks for your post. Happy holidays to you as well.

[@clarkeblacker]

You could tell that it was a 1965 or 64 by the faceplate that referred to the Fender Electric Instrument Company. That makes it pre-CBS. It is in astonishingly good condition. I own a 1964 Super Reverb myself, but I have played through many Bassmans. They're really great amps!

[@vintageelectronicsrepair9206]

You're correct of course. Don't know why I didn't think of that. Thanks for the comment.

[@jjsant3250]

True 5881 tubes are 23 watts. Those are likely 6L6GCs posing as 5881 and would be 30 watts.

[@vintageelectronicsrepair9206]

Yep. Re-branded Sovtek. Thanks for the comment.

[@alanpecherer5705]

I remember when you could buy as many of those as would fill an airplane hangar for $125. each.

[@rodneyouellette3429]

The 8mF filter cap indicates that this is an AA165 and not an AA864. I have an identical one made in the 9th week of 1965. Great video

[@vintageelectronicsrepair9206]

Thanks. It's true that the additional filter cap is not on the original AA864 schematic, but the tube chart is AA864, the phase inverter coupling cap is 500 pf instead of .1 uf, and most importantly, the normal channel does not go through the second gain stage. Must be transitional. Does yours have these characteristics as well?

[@rodneyouellette3429]

@@vintageelectronicsrepair9206 Exactly the same. Fender would use previous tube charts until they ran out and then updated them so they do not always match the circuit! My AA165 has the AA864 tube chart that has OC stamp (March 65), FN0965 cabinet and chassis stamp and serial number A05XXX so it was made in March of 1965. Yours was made a week later. The AB165 began shortly there after so there only a couple of months where AA165 were make. I have not updated the electrolytics yet and i am debating if i will have the Bass channel converted to AA864. The normal channel of the AA864 and AA165 are identical. Uncle Doug has a great video explaining the difference between the two. kzbin.info/www/bejne/oXiWkoerpt2UY7c Keep up the good work!

[@Pgu9de]

Seems like there was some hum. Did you address that?

[@vintageelectronicsrepair9206]

I did not eliminate it entirely. It's not as prominent when it's not sitting on top of the other amp. I adjusted the heaters that had been moved when I installed the new cord, but there is still some hum. Apparently, it's common to replace the two 70 mfd filters in series with much higher values, but for now the owner was okay with keeping it as close to stock values as possible (the F&Ts are 80 mfd).

[@garyeggleton1142]

I was under the impression that the 864 didnt have the 27k dropping resistor and extra filter cap...

[@vintageelectronicsrepair9206]

You're correct that it's not on the schematic. Transitional perhaps?

[@garyeggleton1142]

@@vintageelectronicsrepair9206 I believe that that amp is transitional

[@rodneyouellette3429]

AA165

[@pacocalimari]

You seem to tap and slap a lot in there. Its hard for me to look at.

[@vintageelectronicsrepair9206]

I get that, I do, but when you have an intermittent issue, the chopstick method is pretty standard troubleshooting. Also, Fender designs were pretty dang sturdy. If it can't take a bit of poking, it's not going to last long on the road. Thanks for the comment.