PV ValveKing Combo dead

[1WoodHippie]

I've got a PV ValveKing 112 that's mostly dead. The heaters have voltage and I've got high B+ going to the power tubes but i've got no output and the Power On LED won't light. So that's the first thing I'm trying to tackle. Why won't the power light come on... (if you stare real hard you can barely see a faint light in the bulb)

In the Schematic I've got 19VAC coming out of the secondaries P211 to P215. 19VDC on the left of R213 and 18.9 on the right of R213. And 15.5VDC on the right of R212.

Measuring across R206 i get .08VAC. Measuring from P215 to the left of R206 i get 18.2VAC, to the right I get 18.1VAC.

Thanks in advance!

[The Dude]

Can you post a schematic?

[1WoodHippie]

My apologies. Forgot to attach to the orig post.

Schematic attached...

[The Dude]

What is the voltage across the LED itself?

As far as the "no output" symptom. The amp has an effects loop. Run a signal into the effects return and see if you have sound. Conversely, run the effects send into another amp and see if you have sound. This will help us determine if you have a preamp or power amp problem, or if the switching jack itself is the problem.

[1WoodHippie]

1.17VAC across the legs of the LED.

[The Dude]

1.17VAC across the legs of the LED.

That is more than enough voltage to light an LED. I suspect the LED itself is in crap- or not seated in the jewel properly.

[1WoodHippie]

hmmm... this is actually mounted in a plastic post that is attached to the board and the LED itself actually sits way behind the jewel bulb. Both legs of the LED are in there good and don't seem to be loose. And you can actually see it light very faintly.

[The Dude]

Just looked at the part description in your schematic. This is a super bright LED and many of those do require more voltage- my bad. Possibly R206 has started to go open? Make sure it still measures 1K.

Whatever the case, it's a pretty simple circuit - - power to resistor to LED to ground. Not much to it.

[1WoodHippie]

1.2VAC on the left side of R206 and 1.16VAC on the diode side. (measured from ground)

[g1]

That sounds kind of low for that transformer winding. F203 is good? What is the AC voltage between P211 and P215?

[1WoodHippie]

19VAC coming out of the secondaries P211 to P215. F203 is good.

[g1]

Then I would expect around half that (9.5V) at the top of R206 but you have 1.2V. Maybe a ground fault or blown ground trace? What is your DC voltage on either side of R212 ?

[1WoodHippie]

16VDC and 19VDC on either side of R212...

[The Dude]

Did you ever check R206?

[1WoodHippie]

.7VDC and .6VDC on each side of R206.