Fender 4x10 DeVille No Output

[Billy Penn]

Hi all. Happy holidays!! I've read the other threads related to my issue but none of them apply. I have a mid-90's DeVille with very low to no output. Here is what I have so far:
1- Plug guitar into effects return and it sounds loud and clear.
2- Used a cable to go from effects send to effects return. Still low output.
3- Preamp out to another amp, no sound.
4- All voltages are fine on all 12AX7's and 6L6's.
5- Re-flowed a bunch of solder joints.
6- Checked all plate resistors. All read fine.
7- Have +/- volts going to opamps and relays.

I do not have a scope at this time. Anyone else have any experience with a low to no output DeVille with these symptoms? Any help would be greatly appreciated!! Thanks!!

[Jazz P Bass]

O/k.
You narrowed it down to the preamp.
The best way to check a tube is to measure the plate & the cathode voltages.
That is where I would start.
You can tell real quick if the tube is not conducting.
Generally speaking, either the plate will be high or the cathode will be low.

[Billy Penn]

Thanks for the reply Jazz P Bass! All voltages to the tubes are correct. I also swapped in another set of tubes. Tubes are good, voltages are good but still have very low output. I checked the two 470 ohm resistors and their solder joints. All good.

[52 Bill]

Start at the output of the preamp and work forward till you find out where the signal dies out. I find that when you take voltage readings at the plates, it will cause a noise or pop in the signal output. When you check the voltage at the input grids it will produce a hum in the signal output. So if there is a noise when you check the plate voltage then, check the input grid and see if there is a hum produced. If there is, then move to the next tube stage in front of this stage.

When you find the problem stage, check the coupling caps for open circuits, check the wiring to and from the pots, check the pots, etc.

[Jazz P Bass]

Fender Hot Rod Deville Service Manual

Here is the service manual.
The voltages in a circle are Vac (signal)
The voltages in a square are Vdc. Static voltages, no signal applied.
What I do when I get one of these amps is, first, yank the power tubes.
With the chassis on the bench, tubes up, I probe the 6L6 sockets.
Unit on , standby off, you can read the bias voltage ((pin 5) & the heaters (pin 2 & 7)
Then I activate the standby & measure the plates & screens.
At this time I inject a signal into the front end of the amp &, monitoring pin 5, Vac, "look" for the signal.
If it is not at pin 5, it is time to hunt down why the signal does not reach pin 5.
If the signal is at pin 5, then I will insert a known good set of 6L6 tubes and hook up a dummy load.
Signal should be at the dummy load.
If not, it is time to really check out the 6L6 socket & circuit & if all else is good, maybe hook up another output transformer.

[Billy Penn]

I get the popping on the PI tube but not on V2 or V1. I may have a bad coupling cap then. Voltages are good. I will check them out. Thanks!!