Fender Hot Rod DeVille 2x12 Low Volume

[goldtop5]

I have a problem with a Fender Hot Rod DeVille that has low output. I tested the signal going from the preamp out into another amp and it seems fine. When I ran a signal into the power amp in. It is very weak. So something is telling me that it's in the output section. Any ideas what could be the cause?

[The Dude]

These amps are notorious for cold/cracked solder on the tube sockets. That would be my first check. This problem is so common I just automatically resolder the sockets when I get one in the shop to keep it from coming back in.

[Pedro Vecino]

Here are some possibilities:
- Fault in the internal send/return connection
- Weak/defective 12AX7 driver
- Open resistor in driver plate (82K usually)
- Open screen grid resistor (470 Ohms)
- Problem with 6L6
- Problems with sockets
- Speakers connected out of phase...

[52 Bill]

Here are some possibilities:
- Fault in the internal send/return connection
- Weak/defective 12AX7 driver
- Open resistor in driver plate (82K usually)
- Open screen grid resistor (470 Ohms)
- Problem with 6L6
- Problems with sockets
- Speakers connected out of phase...

And to add one more to Pedro's list, check the switching contact on the extension speaker jack.

[Bruce / Mission Amps]

Setting aside obvious things, my first suspicion would also be the 1/4w to 1/2w plate load resistors on the phase inverter tube section... 100K and 82K.

[Yelly]

One of the two plate resistors burned will not make the output very weak particularly, maybe weaker, but it will certainly distort alot like you're on the OD channel. Can't miss that problem.
How does the signal look on the output?
If the signal is present but very low volume, could also be a bad OT, quickcheck before dissamble just by using the variac to check normal powerconsumption with and without signal.

[goldtop5]

I found the problem. The driver plate resistor (82k ohm) at the phase inverter was open. I replaced it and the all the tubes as well. Now, this thing is so loud it nearly knocked my head off. Thanks guys!!!

[Randall]

One word... Bruce.

[g1]

One word... Bruce.

No disrespect to Bruce intended, but, to be fair, Vote for Pedro.