AA864 schematic?

[r8burst]

I'm looking for a schematic/layout for my 1965 Vibrolux Reverb, AA864, and can't seem to locate one. Anyone have any idea where to get one? I've looked in all (most all) of the usual places.

Thanks
Tony

[dbx]

The tube chart on my '70 SFVR is an "AA864"...I had it de-modded (PO put in a SS rectifier) and re-spec'd...hopefully to this circuit...haven't spent a lot of time looking for the schem but let me know if you run across one...it would be very informative... :JAM

[billdurham]

You can find your schematic here...

http://www.ampwares.com/ffg/index.html

BD

[r8burst]

Ampwares doesn't have that schematic. Tried all the usual online sources for schematics, and the AA864 is conspicuously absent. Wonder why?

Tony

[mbratch]

The Bassman uses the AA864 circuit, and the schematic is listed under there. This may be one of those cases where Fender just slapped on a handy tube chart. Check out an AA964 (http://www.bnv-gz.de/%7Eooehmann/schematics/fender/Vibrolux_Rreverb_aa964_Schematic.pdf) schematic. Maybe that's what it is really (?).

[r8burst]

I don't think it's a mistake or a case of the nearest handy tube chart. The circuit is mentioned here:

http://www.tcguitar.com/articles/gagliano_pt5.html

under the serial number list at the bottom. Mine falls in the serial number range for the AA864 amps in 1965. And I'm not certain the Bassman schematic would be of much use since mine is tube rectified, and voltages would likely be off. I'll look more closely at the AA964 and see if it's close.

Tony

[dbx]

It is conspicuously absent...I saw that site earlier today http://www.tcguitar.com/articles/gagliano_pt5.html and his s/n list confirms mine to be 1970...this wasn't a "small" run of Vibroluxes on this circuit so it's curious why it's not found on the 'net...could be tucked away in a hardcopy Fender Service manual somewhere...I'm tempted to throw FMC a ten-ner for the schematic...

[billdurham]

Thats really strange.. I knew I had seen the AA864 designation, but didn't connect the Vibrolux Reverb vs Bassman. Sorry.

BD

[mbratch]

It's quite possible that Gagliano's list is showing SNs of amps that have AA864 designated on their tube charts. That's not necessarily proof that the circuit is an AA864. Also, the Bassman and VR preamps are different enough that I'm not sure they should carry the same number. I would suggest checking your VR against an AA964.

[John Phillips]

'AA864' is not a designation for the Bassman, it simply means the first circuit variation for a particular amp in August, 1964. So there could easily be a Vibrolux AA864 as well as the Bassman AA864, which do not bear any relation to each other beyond being designed in the same month.

It's also entirely possible that there is a Vibrolux AA864 and a Vibrolux AA964 (September '64) - Fender really weren't joking when they said that 'specifications are subject to change without notice'! There are even two Bassman circuits from January 1965 - the AA165 and the AB165.

[r8burst]

Confusement abounds.

I thought the original circuit code (AA***) showed when the circuit was instituted, and the revision (AB***) just showed that the original circuit had been altered. Otherwise, most of the revisions were done in the same month/year as the original (i.e. AA763/AB763, AA165/AB165, AA668/AB668, AB568, AC568, etc). Or were they all designed and revised in the same month of the same year?

Tony

[John Phillips]

Many of them were, or there wouldn't have been 'B' designations. Presumably the circuit was prototyped, then revised almost immediately once some little problem showed up in the production examples. Still, the 'A's must have been considered suitable for production originally since large numbers of tube charts were ordered for some of them, and then often used up on examples of the later circuit, which makes things even more confusing :).

They obviously had even more serious trouble with the AC568 Twin, since that's the second revision within one month. This is the time when CBS's new engineers were messing about with the amps though, so not too surprising...

Some were got right first go and not revised too - like the AA864 Bassman, which remained in production for a whole four months! - and the AA964 Vibrolux. I've never seen an AA864 Vibrolux (amp or schematic) but if you have one with that on the tube chart, then they probably did make it for at least a week or two ;) - but whether your amp is actually that circuit or just an AA964 with a left-over chart, you'll only find out by comparing the amp to the schematic.

[mbratch]

Thanks for clarifying John. Just when I thought I had the Fender codes figured out... ;)