Fender 212R 37 volts DC

[ManuCE]

Good evening. I own a Fender 212r. the appliance was left standing still for a few years. I turned it back on but it makes a constant buzz from the speakers. There are 37 volts DC on the PINs of the speakers. I measured all the ceramic resistors and they are good. I also changed all the capacitors including the 4700 microfarad ones. what can I do ? thanks to anyone who can help me

[DrGonz78]

Remove the speakers from the amp. Do not power it up with them connected until the output of the amp is 0 volts. Sounds like a transistor or diode is bad or failing. Check the power supply for stability first.

[Mars Amp Repair]

Hello,
These amps are notorious for developing bad connections on the main filter caps that results in a horrendous Buzz in the speakers. You can ususally just push the caps to one side making a temporary connection for testing. If the buzz goes away, there's you isseue.
I'm not sure that this would cause the symptom you're experiencing, unless you're measuring AC voltage at the speaker output.
Just a though...Glen

[ManuCE]

The strange thing is that even if you keep all the volume potentiometers at 0 there are still 37 volts and a strong hum at the output. Power supply capacitors have optimal ESR.

[Helmholtz]

The strange thing is that even if you keep all the volume potentiometers at 0 there are still 37 volts and a strong hum at the output.

That's not strange as vol. pots can just lower AC (signal) but not DC.
37 Vdc can kill a speaker in short time.

Please find and post the schematic.

[x-pro]

please

[x-pro]

What is the polarity sign of the 37 V voltage? (the black probe of the meter is pressed against the body)

[The Dude]

Q12 & Q13 are known to have problems in this amp. I'd first check those.

[ManuCE]

Good morning. I tried to desolder the q12 transistor and I no longer have direct current on the final. the amplifier works because it correctly amplifies the signal that enters via the Jack. the transistor is recognized by my tester as a double diode!!

[x-pro]

I tried to desolder the q12 transistor .......the transistor is recognized by my tester as a double diode!!

Figuratively speaking, that's fine. Bipolar single transistors are all like that.
So now you don't have Q12 in your amp?

Then it's good. There are still many parts that are superfluous.....

[ManuCE]

Good evening. I have some good news. as I wrote before I desoldered the q12 transistor. I replaced it with a pnp transistor of similar characteristics. the amplifier thus works correctly and does not emit any strange voltage at the output. I then ordered the A1013 transistors and a C2383. I think I've solved all the problems, I'll keep you updated when the right transistors arrive. Thank you

[ManuCE]

I replaced the transistors you indicated. Now the amplifier works perfectly. Thanks thanks thanks