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Hi mates, just looking for someone that can help me,

Problem is: amp sounds little bit like crap, early break up in the clean channel, less volume than normal, but still sounds, even enough for a band rehearsal.
Had a look and noticed that from both power tubes only one was "red" and "hot", the other one is not "lit" at all and it's barely warm.

First thought, dead tube. Tries another couple. Same thing happens. huh. Next try: swithched position of the tubes, the tube that was "red" now is "off", the one that was "off" now is "red", sounds the same (crap).

So I checked voltages to find the fucked up part in the circuit, but circuits around both tubes look ok, similar volatages in the pins of both tubes.

I'm lost. Any thought, welcome. Thanks. Love.

First - if you are not comfortable with following the steps below - take the amp to a tech. There are deadly high voltages in the amp.

Tubes can be bad - right out of the box. Usual cause of the symptom you describe is a bad tube...but it seems to follow the socket.

Is the glow red or orange? Red means that the plates in the tube are fried OR you have an issue with bias or a component.

The heaters should glow orange if you are in 'standby'. When you turn standby off, the high voltage is turned on to the tubes and they start conducting current. If the tubes can't handle this, they start red-plating - you may also hear a hum before the fuse (hopefully) blows and prevents damage to the board. The plate that would be bad to get red (red-plating) is the inner plate.

Check the socket where the tube is glowing and make sure that there is no damage - this can cause the tube to red-plate as well.

Carbon buildup around the socket (front and/or back) is also a sign that something internal is going or gone.

To check bias - remove back cover. Turn amp on and let it warm up - no instrument plugged in. Bias Pot is R82 (blue circle thingy with a notch in it next to two boxy-looking resistors. Use multimeter set on Milli-Amps (mA) - black probe attached to ground (somewhere on chassis), red probe (above the power tubes) is on the corner of the circuit board - it is marked. Move the standby switch to active (standby is off) and check mA reading. Fender recommends 60mA, 68mA is very comfortable and warm. If you set it too low, you will hear a buzz following low notes.

To further troubleshoot - check the plate voltage of the power amp tubes (pin 3) with the multitester set on VDC - HIGH (1000). The reading should be 400+ on all tube sockets (indicates that Output Transformer is OK when voltage is over 400) - if one is lower - your screen resistor is wonky and needs replacing. The screen resistors but they are R61 and R62. Recommend (if needed) 5W 750V, I believe they are 470ohm. You can pop these up to 1k to prevent a screen resistor failure if this is the issue (recommended).

If all is still fine, Phase Inverter (V3) - check voltages at pin 1 and pin 6 (black lead at ground). You should get 200+ VDC at these two points. If one is zero - then either R57 or R58 has gone bad. The resistor is replaced with an 82k 1/2 watt unit.

This should get you started.

Great first post, claskowski! Excellent knowledge.

Much better description of the procedure than I could give to someone on a forum, that's for sure.


Cheers...
Steve

Thank you claskowski, I think this will help me a lot!! I will work on the amp this afternoon with your procedure,

About the glow, that's orange I would say. Switching stanby on and off doesn't change the glow or temperature of tubes.

I was checking voltages before, but without knowing exactly what to look for. So I better have a new look today; will report whatever I find.

Regarding safety issues, I very carefully handle this stuff, as I know how dangerous it is, don't worry about that.

Then check you have heater voltage right at the pin sockets,, look for cracked solder joins.
Phil.

Ed opps, misread that.
Sounds more like that socket has lost it's bias voltage.

I'm on the amp, right now (just having a little rest). I think I got something... will tell you soon...

...Back from the battlefield...

The socket!! The solder in pin 7 (tube 4), the heater. I also added some solder to all the pins, to prevent future problems with other pins.

I also adjusted bias to 68, as claskowski said. Sounds sweet!!

Thank you guys!

Thanks for the thanks!!!

Sorry I didn't think about resoldering the sockets - I should have known. The DeVille is similar to the Deluxe and the Deluxe has this as a problem. The tubes will get hot and soften the solder. In the past I have purchased three different Deluxe amps for very little money, fixed this particular problem and sold them for a bit of a profit. Something to check for - if you see one of these in a pawn shop, try it out, ask if there are any problem, check the amp. You can usually (after looking a bit and bargaining with the owner) get one in a condition needing a little time and a few dollars (usually less than two hours and $10). Easy to fix and a good amp.

The last one I purchased was only a few weeks ago - after about 15 minutes, smelled like something was burning - bought the amp for nearly half of the asking price (under $175) and checked it out. Issue was a screen resistor that burned.

Glad I could help!!