Amp repair where do I start

[LoveChet]

I am electronic technician but have limited test equipment and guitar amp repair experience. I have a modified Fender Deluxe Reverb that sounded super (i mean Chet Atkins super) until it fell over a few years ago. After it fell over it sounded crappy but worked, I think I can get it going again but I need direction. I had all 9 pins tested and were good. I replaced the power tube and replaced the output tubes with Brimar 6V6 and set bias to 20, (i did note that to get the bias to 20 I had to increase the pot quite a bit and maybe Brimar was a bad choice). Right now it isn't operating, I can get a little sound out of it by increasing the Master volume (a mod addition) but its defunct. Where do I start ?

[Helmholtz]

Where do I start ?

Best post a schematic that includes the mods and circuit voltages.

[LoveChet]

I have no schematics and voltages. I can get dc plate voltages if I got access to the head, I would need to draw a schematic of whole thing which I have not. I only drew a schematic of the fx loop .I was thinking of getting an analog scope and a signal generator so I could trace the signal. I know what 400v feels like from electronics school so don't worry about me. As an aside do you think that putting in Brimar 6V6s was a poor judgement for q Fender Deluxe ?

[Helmholtz]

As an aside do you think that putting in Brimar 6V6s was a poor judgement for q Fender Deluxe ?

Nothing wrong with Brimar 6V6s as long as they perform like new.
It shouldn't be a problem to draw the actual schematic for an electronic technician.
Use the original Fender schematic and edit for mods.
It's not a complicated circuit.
A schematic would immensely help with remote troubleshooting.

For troubleshooting best start with measuring supply node voltages followed by preamp tube cathode and plate voltages as well as power tube grid and screen voltages.

[Tom Phillips]

I have no schematics ...

Gary,

Please tell us a little more about the version of your Deluxe reverb. They roughly break down into several classes commonly referred to as classic Blackface, Silverface, and re-Issues. It would probably be easiest if you post some photos of the amp including a gut shot of the chassis removed from the cabinet. If you can do that, then I can post the appropriate service information that you can mark up. The Deluxe Reverb circuits are almost identical anyway but it would be nice to start with the closest service information.

I have an additional thought about the Master Volume Mod that you mentioned. If a connection associated with that mod came loose when the amp fell over that could easily cause of the symptoms you described. If so, then re-soldering a loose wire may be the only repair needed.

Cheers,
Tom

[mozz]

If it fell over, the speaker could be the problem.

[g1]

I'm attaching the schematic for the re-issue amp. For repair purposes it is close enough if you have an original.
One very simple thing that can create a problem like this is if the speaker gets connected to the 'ext. spkr' jack instead of the 'spkr' jack.

[The Dude]

If it fell over, the speaker could be the problem.

That was my first thought. If it fell over, it's possible the gap shifted (magnet broke) on the speaker and it is seized. Please test the speaker with another amp, and/or test the amp with a known good speaker.

[Pedro Vecino]

I only drew a schematic of the fx loop

Things get complicated...
If so and it worked, almost the first thing I would do would be to bridge the send with the return by connecting a cable between them.

[LoveChet]

Its an original silverface. You folks are a lot of help. I plan on making a full schematic from input through output stage and noteing mods as I go. I'll check some voltages first as you suggested and a schematic will help me with that. I'll also check out spkr. I've got a scope, sig gen, and dummy load on the way. As an aside I lost the end section of my left middle finger in a fall so when I get the amp going again I may have to scale back to easier Chet tunes. Maybe also might have to put down the Nashville Classic for the Country Gent as Classic sounds wonderfully but wider neck is mire difficult to chord. I also might start with Gabby tune as two big strings are defined. Im also talking to my grand daughters boyfriend on how to make a prosthetic. He's into 3D scanning. I'll be back !

.

[LoveChet]

Looking near input end of circuit board there are two large green capacitors side by side. Why are they glued together ?

[Tom Phillips]

Looking near input end of circuit board there are two large green capacitors side by side. Why are they glued together ?

I have never seen that in a stock original Silverface as you reported the amp to be in your post #10. Therefore, I can only guess that it's a mod or some sort of repair attempt. In cases like this, it would be good if you could attach photos.

[LoveChet]

Trying to upload photo

[LoveChet]

[Tom Phillips]

Regarding the photo in post #14.
I'd say that someone glued the caps together after the amp left the factory. In my opinion, there is no need to do that. There are also mods visible.
If you can, please show a clear photo showing the full inside view of the chassis so we can see what you are working with.