peavey duel 212 no output

[nosaj]

Anyone seen this before(the pics that is.
Has no output. preamp out works.

3 tubes test good. The one that looks like it was super glued into the socket is shorted plate to cathode.

Good sockets pin 2 25vdc 54ac
pin3 485
pin4 480
pin5 -40
pin7 25vdc 54ac

The bad socket voltages are intermittant but pins 6 and 7 show 25vdc 54ac.

Filament voltages seem way off. I'll pull out the simpson to verify them when i have a chance. Inside it looks like a glue mess any idea what it is? It doesn't look like it is from the caps though.. looks like I will also have to drill out the rivets to get at pc board.

Ot primary blue and brown 80 ohms blue and red 40 ohms brown and red 39 ohms.
Schematic attached.

Thanks,
nosaj
DUEL_212.pdf

[The Dude]

Candle wax? Maybe someone set a candle on top of the amp? Mr. Obvious says: You'll have to clean all of that gunk out of there before you can really know what's going on.

[nosaj]

Candle wax? Maybe someone set a candle on top of the amp? Mr. Obvious says: You'll have to clean all of that gunk out of there before you can really know what's going on.

I really think it will be easier to replace the socket it's like a hard glue. I had to use a screwdriver to pry the tube from the socket..
Voltage measurements were with tubes removed.


nosaj

[52 Bill]

I really think it will be easier to replace the socket it's like a hard glue. I had to use a screwdriver to pry the tube from the socket..
Voltage measurements were with tubes removed.


nosaj

Have you tried to heat the stuff? If it melts You could use a heat gun to clean off the bulk of it.

[g1]

Some kind of spill residue, the stuff on the board looks to be the same as the stuff on the socket.
Check the heater voltage with one probe to pin2, the other to pin7 (not with one probe to ground).

[oc disorder]

Failing that try the opposite , freeze spray, makes it more brittle and snaps off. Well so I'm told....

[nosaj]

I really think it will be easier to replace the socket it's like a hard glue. I had to use a screwdriver to pry the tube from the socket..
Voltage measurements were with tubes removed.


nosaj

With simpson 260 getting almost 30 volts at f2 and acfil1 and acfil2 . black lead to ground red lead to j47 and j48. I'm thinking whatever caused the 6l6 to short K to P may have messed up filament voltages.
To patch in a 6.3v I should need one about 4 amps i believe.

Can anyone tell from the schematic what ACfil1 and acfil2 should be?

Thanks,
nosaj

[nosaj]

Some kind of spill residue, the stuff on the board looks to be the same as the stuff on the socket.
Check the heater voltage with one probe to pin2, the other to pin7 (not with one probe to ground).

5.7 volts no powertubes in 12ax7 are installed.. Something is still keeping the filaments from lighting. Guess I'll bite the bullet and remove the power board. Won't be able to get to it till Monday though.
nosaj

[nosaj]

Have you tried to heat the stuff? If it melts You could use a heat gun to clean off the bulk of it.

Not yet but the residue is down in the socket. If all the other stuff checks ok I think it'd be wiser to just change it.

nosaj

[Enzo]

READ the schematic. Your AC 6v heater supply is connected to +25vDC by R81, right there by the fuses on the drawing. This elevates the AC heater supply by 25v DC for hum abatement. Perfectly normal to find DC voltage there. Also, look at V1 and V2, their heaters are wired in series from +23v to ground. Likewise V3 and V4 are wired in series from -23vDC to ground. The 6vAC only powers the power tube heaters.

AC FIL is plain old 6.3vAC. You measure it from one to the other, NOT to ground. You will get about 25vDC to ground from either one, AC readings to ground are meaningless. AC 6v should appear from ACFIL1 to ACFIL2. I'd be very surprised if your 6v heater winding is bad.

Whatever spilled in there, you need to clean it off before anything else matters.

You might get close to 6vAC from pin 2 to 7 on a socket, but with no tubes installed, and power off, measure resistance from pin 2 to pin 7. it ought to read like a short circuit, as the heater winding has VERY low resistance. if you measure high resistance, that explains no heaters lighting. Your meter might be just picking up voltage from the air.

[The Dude]

5.7 volts no powertubes in 12ax7 are installed.. Something is still keeping the filaments from lighting. Guess I'll bite the bullet and remove the power board. Won't be able to get to it till Monday though.
nosaj

So you have 5.7V on the sockets and no filaments lighting? Is that measured right at the sockets or somewhere else?

[nosaj]

READ the schematic. Your AC 6v heater supply is connected to +25vDC by R81, right there by the fuses on the drawing. This elevates the AC heater supply by 25v DC for hum abatement. Perfectly normal to find DC voltage there. Also, look at V1 and V2, their heaters are wired in series from +23v to ground. Likewise V3 and V4 are wired in series from -23vDC to ground. The 6vAC only powers the power tube heaters.

AC FIL is plain old 6.3vAC. You measure it from one to the other, NOT to ground. You will get about 25vDC to ground from either one, AC readings to ground are meaningless. AC 6v should appear from ACFIL1 to ACFIL2. I'd be very surprised if your 6v heater winding is bad.

Whatever spilled in there, you need to clean it off before anything else matters.

You might get close to 6vAC from pin 2 to 7 on a socket, but with no tubes installed, and power off, measure resistance from pin 2 to pin 7. it ought to read like a short circuit, as the heater winding has VERY low resistance. if you measure high resistance, that explains no heaters lighting. Your meter might be just picking up voltage from the air.

Measuring 200ohms , The ribbon cable on the power board section j47 acfil2 shows scorching. Gonna remove the socket see if i can find one local

nosaj

[Enzo]

200 ohms for a heater winding? Not on my watch. You have any other tube amps around? Or PTs for them? Measure the resistance of the 6v winding, that is what to expect.

DOn;t take my word for it, measure right at J46, J49 where the transformer wires come onto the board. Are the wires yellow maybe? Measure resistance there. if it is not the same at the tube sockets, then there is resistance in the wiring. And now that I look more closely, yes, that ribbon from the main board to the power tube board is burnt. The solution is to hard wire it. Solder wires from one board to the other for the two 6v wires in the ribbon.

[nosaj]

So you have 5.7V on the sockets and no filaments lighting? Is that measured right at the sockets or somewhere else?

on 3 of the power tube sockets. Just got the socket desoldered gonna try heating it tomorrow in an old toaster oven to see if goop will come out. And check local for a pcboard tube socket.

nosaj

[nosaj]

200 ohms for a heater winding? Not on my watch. You have any other tube amps around? Or PTs for them? Measure the resistance of the 6v winding, that is what to expect.

DOn;t take my word for it, measure right at J46, J49 where the transformer wires come onto the board. Are the wires yellow maybe? Measure resistance there. if it is not the same at the tube sockets, then there is resistance in the wiring. And now that I look more closely, yes, that ribbon from the main board to the power tube board is burnt. The solution is to hard wire it. Solder wires from one board to the other for the two 6v wires in the ribbon.

.5 ohm at the yellow cables.

nosaj