Late 1960s Fender Deluxe Reverb Guitar Amp Issues

[eleventeen]

Wait, I thought you said you had it working semi-OK and then a hum started. If you had it working semi OK and then this hum started, then the conclusion is you don't (yet) know what's causing the hum. Heater to cathode shorts are pretty rare. Not "never" but very rare.


If it was working, even briefly; but more than just a few seconds, then those mods, while they might depart from stock...quite possibly do not amount to major surgery. In other words, one value cap was removed and another value was put in its place. This is a kind of mod that is done for tone. But if it is done with functioning solder joints, then it will not completely kill the operation of the amp. This means you have kind of a bifurcated path to take.


If you want to "restore it to stock", then you really have to trace out and ohm-out things (that means essentially every wire) and that involves staring at the thing for long periods of time with a schematic and layout. It can be astronomically tedious. That effort, the "return to stock" makes the assumption that amp DOES NOT WORK as currently constituted. But it DID work.


A skilled eye could see what's going on very quickly. IMHO. Easier done than said. Can't always see it from a photo. I got to this discussion late but the "no B+ to the first tubes" is almost always a bad intranode R, under the doghouse.

 
I say again, if this belongs to someone else's kid I have to assume (but I do not know) there is some sort of upper limit that YOU are going to contribute to the effort. I can talk about what I would do for MY amp because I have done that, and more, to my '72 Deluxe Reverb. If I were to do "that" for someone else, I could see giving away a few hours of focused time but maybe not a dozen.

By the way; if you like, prefer, or are used to neat wiring, even Fred Flintstoney wiring like (earlier than yours) Fenders, then the so-called spaghetti wiring of 70's Fender amps is certified and guaranteed to drive you nuts. It does. You could talk to 100 bench techs and they would all say they hate it. I am just saying, that wiring looks bizarro to *everyone*, even those who are used to Fenders.

[captainclock]

I will tomorrow after i get off work, but not now as i need to get to bed soon as i need to get up at 5:30 in the morning in order to get around for work so i can be in by 7am.

[Paul1453]

Hum, as a general symptom, puts you right back in the Power Supply section to start.

Maybe there were other loose/poorly connected or just about to fail components right where you were last time?   

[captainclock]

Hum, as a general symptom, puts you right back in the Power Supply section to start.

Maybe there were other loose/poorly connected or just about to fail components right where you were last time?   

Well that's the thing I resoldered a loose resistor that was in the power supply capacitor box that was preventing the 7025s from getting B+ current in the amp and when I did that the amp worked flawlessly without any hum for about week until the day after a friend of mine tested it with his electric guitar so we could hear what it sounded like. Then it started to develop a hum a low volume 60hz hum (or perhaps a 120 Hz hum) anyways I assumed it was because the old Mallory Power supply caps finally started taking a crap so I had ordered some new capacitors and installed them and put the amp back together and sure enough the hum was still there which means something in the circuit is still causing that hum, but as to what I'm not sure.