Vox AC30C2

[pnut5150]

Just the socket, tubes are new, I can put the tube in V6 in any other position and it works great.

[Enzo]

SO with NO tube in the socket, the voltage is still there?

[pnut5150]

Yep with no tube, but now let me add another crazy statement. Tonight amp sounds almost normal, PI voltages are close to normal, I can put tune back in V6 and heater fuse won't blow!! And the crazy voltage on pin6 of V6 isn't there... Scratching my head

[g1]

Is this by any chance double sided circuit board?
Did you find any type of residue on the V6 socket?
At this point I would suggest you remove the V6 socket and inspect it's underside, also check for any solder "blobs" under it. If no evidence of any problems, suggest you at least swap it with one of the others and keep track of where you swap it to.
This will help further troubleshooting.

[The Dude]

Is this by any chance double sided circuit board?
Did you find any type of residue on the V6 socket?
At this point I would suggest you remove the V6 socket and inspect it's underside, also check for any solder "blobs" under it. If no evidence of any problems, suggest you at least swap it with one of the others and keep track of where you swap it to.
This will help further troubleshooting.

Yes, and when/if you remove the socket, check the voltage on the pad that pin 6 solders to (without any socket there). This will tell us if it's a socket problem or elsewhere on the PC board.

[pnut5150]

Ok, been tied up last couple days, I will change tube socket in a few and post results. Thanks again

[pnut5150]

Ok, here's what I got....there was residue all over the boards around the rube sockets. So I cleaned them all, resoldered them all, and changed V6 socket. No change. I also resoldered all do the jumpers to pre & power tubes and still no luck. Voltages were not crazy on pin 6 either like they were. Well when I first turned amp on it sounded pretty good, voltage on pi was pretty close to normal, then it started dropping, the sound was getting lower and voltage to pi was getting weaker. When I turned power off the volume got loud until amp died, turned it back on and it was normal for a second. To make a long story short...the two caps soldered together were bad (power surge caps) and not getting but 55.5 ac volts to tranny after amp was on for a few minutes. Now after I removed them, amp sounds great, but I still can't guitar to work through the effects loop.

[g1]

This is very confusing, can you be more detailed in your explanations?
The power surge caps you refer to are the surge suppressors in the PT primary circuit?
Now you removed them and the amp works properly, but not if you run into the FX RETURN jack?
What happened to the weird voltages on V6 socket?
What happened to the voltages at the phase splitter tube?

[nickb]

Ok, here's what I got....there was residue all over the boards around the rube sockets. So I cleaned them all, resoldered them all, and changed V6 socket. No change. I also resoldered all do the jumpers to pre & power tubes and still no luck. Voltages were not crazy on pin 6 either like they were. Well when I first turned amp on it sounded pretty good, voltage on pi was pretty close to normal, then it started dropping, the sound was getting lower and voltage to pi was getting weaker. When I turned power off the volume got loud until amp died, turned it back on and it was normal for a second. To make a long story short...the two caps soldered together were bad (power surge caps) and not getting but 55.5 ac volts to tranny after amp was on for a few minutes. Now after I removed them, amp sounds great, but I still can't guitar to work through the effects loop.

Stop! Bypassing safety components is not likely to lead to a happy ending. Could be the amp is drawing too much current and that is causing the safety thermistors to kick in. They will shut the amp down in just over a minute if the input power is around 550W. Now they could be bad, in which case you could check by replacement. Better to measure the input current. I keep one of the kill-a-watt do-hickies handy for that.

http://www.legacydistribution.co.uk/...istors/SCK.pdf

[pnut5150]

Ok, sorry I didn't explain as good as I thought. I didn't have the crazy voltages on v6 anymore, I only had 55vac from the power cord(120vac)to transformer. Therefore low voltage was present in the amp. The reason being was the two surge protector caps wired in on the main power to power switch were bad. I am only guessing that the low voltage in was causing all of my crazy meter readings. Everything is normal now, amp sounds great as I used it for a couple of hrs this evening. Not sure about effects loop..could have been another issue before all this arose. As far as the the caps hurting anything, I can put 2 back in no biggie, they are kinda like a fuse or spike diode that takes the AC hit before transformer.

[Jazz P Bass]

The parts that where holding off the 120Vac are called NTC current inrush limiters.

That particular part should read 10 ohms without power applied.

http://img.docstoccdn.com/thumb/orig/126956366.png

Part#: SCK15105MSY.

[pnut5150]

Does that make sense with all the crazy readings?

[Jazz P Bass]

Yup.

[g1]

Does that make sense with all the crazy readings?

For the readings that were fluctuating it makes sense. For the reading where you had one power tube socket with weird readings but the other sockets were ok, the NTC problem could not cause the weird reading. That was probably the residue issue.

[diydidi]

Not to hijack the thread. I have one here for repairs with a real bad hum. Anyone have similar experience with these amps?