This could be power supply, it could a bad coupling cap, could be just a bad connection.
This is not the kind of amp to be sticking your fingers in, unless you know what you're doing and have the proper test equipment. I suggest taking it in you a tech.

 

Too late. I have taken the board out, and see one problem as outlined in this video. The Two resistors he talks about at 57 seconds, have turned the board a little toasty coloured, and one wire lead has come free from the board and I can see the tracing is still attached but is lifting off the board. The other looks like someone has re-soldered it and there is a bigger solder blob on it than any other solder connection on the board.

So I would think the first thing to do is replace the 3 resistors he recommends, and cut the traces from them and use a wire to go to the next soldered component on that tracing. Then look at the filter caps...

 

Well since you're down the rabbit hole...
That is a common problem, be careful, those traces are delicate and it's easy to make things worse. Keep the resistors raised off the board to dissipate heat better.
He's re-capped that amp too.
While you're in there you might as well look at that too.
Just make sure powers drained off.

 

Well since you're down the rabbit hole...
That is a common problem, be careful, those traces are delicate and it's easy to make things worse. Keep the resistors raised off the board to dissipate heat better.
He's re-capped that amp too.
While you're in there you might as well look at that too.
Just make sure powers drained off.

Thanks. Yes I was planning to do exactly what you describe. I need to get a resistor to drain the caps. The traces are definitely lifted off around the ceramic resistors. That may just be the start, so I will get the caps and resistors and do a major swap-out.

Are there brands of resisters and caps that are preferred for amps?

 

I was doing some testing, and found:

Some knobs work, and some have no effect. The channel switching button, master volume and presence do not have any effect. The volume, drive, bass, middle and treble do work.

The amp is not very loud, and a bit distorted and fuzzy.

 

Have you rolled the tubes. That distorted and fuzzy sound screams blown preamp tube to me. IIRC the two channels share V1, and V2 is added in for the drive channel.

 

For those large resistors i prefer Vishay wire wound, but there are many other choices. I didn't like the radial caps in place of axials in that video, but it works. The newer Illinois caps are fine (those grey ones shown are lousy though), there's also Vishay/BC, and F&T, and United Chemi that are quite good.

I'll have a look at the schematic later and see why those controls don't work .

 

PI plate resistors are notorious in this series for going open (one of the 2) resulting in lower output and earlier distortion.
Are you switching channels with the footswitch, or are drive and volume both working at the same time?
Anyway, if those 2 big resistors aren't connected properly, testing isn't going to tell that much.

 

Not with the footswitch, with the little channel switch on the control panel. It has no effect. I was talking to the original owner and he said the reverb went out some time ago. The amp was also doing random channel switching, all symptoms of those resistors, according to the video.
The first thing I will do is replace those resistors and glue the lifted tracing back down.

 

I will need to find out the value of the resistors, as well as a good brand, and a cost effective supplier.

 

They are 470 ohm 5w resistors. The drop 48v down for the zener diode regulators for +/-16v. This 16v is for the opamps, control circuitry and reverb driver. That whole part of the power supply could possibly be most of your issues.
Here's a link to good resistors
AC05000004700JAC00 Vishay BC Components | Resistors | DigiKey
Also take a look at C39 - C42 as well as zener diodes CR13, and CR14.
You do have a schematic I presume?

 

They are 470 ohm 5w resistors. The drop 48v down for the zener diode regulators for +/-16v. This 16v is for the opamps, control circuitry and reverb driver. That whole part of the power supply could possibly be most of your issues.
Here's a link to good resistors
AC05000004700JAC00 Vishay BC Components | Resistors | DigiKey
Also take a look at C39 - C42 as well as zener diodes CR13, and CR14.
You do have a schematic I presume?

Thanks for the info. No I do not have a schematic...

What about all the filter caps and power caps? I might as well replace at least the filter caps, and I saw a vid where the power caps were also replaced as a good measure.

This amp was new in 1995, and gigged by a pro player. The amp owner was teaching lessons at a music store and the owner (who we suspect was not very knowledgeable) said it was the transformers and not worth repairing. My friend said in that case the owner could use it for parts. The store was closing, and the owner sold it to me cheap. I bought it to try to fix it and I will be giving it back to the original owner once (if) I get it working again.

 

Between Digikey and The Tubestore, you should be able to get all the parts you need.
You can also find the schematic here:
Fender Amp Schematics - www.thetubestore.com

 

What is the 3rd resistor he replaces in the top left corner?
I have synced the video to the spot where he points it out.

 

That's R97, a 1.2k 2w resistor. It's part of the footswitch circuit.
You really should learn the basics of these schematics. This amp is particularly good as it gives a board layout, all the test points and voltages you should read. It's fairly easy to get the hang of.

 

Attached is the schematic and board layout under discussion.
As far as learning to read schematics, check out the 'how to read tube amp schematics' on the page I'll link here. I'm not vouching 100% for Rob's site as we all make mistakes, and I've found some things I don't necessarily agree with, but it'll serve to get you started:
Amp Stuff

 

I happened to be in a Hot Rod Deluxe recently. The amp had been fixed once already for the two hot resistors. This time the PCB traces were lifting off, from the previous repair. I built a jumper wire and bypassed the damaged traces. Owner is happy again and has been playing the heck out of it he claims.

http://www.prowessamplifiers.com/schematics/images/hotrod_deluxe.pdf

 

My board is like that. I replaced the ceramic resisters with new ones. I added jumpers where it looked like they were needed and the was a slight improvement but it didn't fix it. I think the 2 diodes right around there may be bad as they have the burning around them too.

 

Here's where you are going to need to do some testing. Specifically voltage testing, otherwise you are just shooting in the dark.
Those resistors you just replaced are the first place to start. Download the schematic and go to the board layout. It shows all the test points. Those resistors should have +/- 48 volts DC on one end, and +/- 16V on the other. Referenced to ground (chassis). If that is correct, it isn't the diodes. Then go to all the little integrated circuits (opamps). Pin 4 and pin 8 on those should be +/-16V as well. If not there is where your problem lies. If all that is correct, you will need to test for high voltage on the tubes. That's the tricky part as this could kill you.

 

That's the tricky part as this could kill you.

Quoted for emphasis.

BE CAREFUL!!...Sorry....Captain Obvious at your service.