Spark while voltage testing

[Deke609]

Hi Krishk - I'd follow PB's advice here and really scrutinize the green heater wiring that runs between the two tube sockets.

... the green twisted wiring going from the 8 pin socket to the 12AU7 may be loose at either end.

No 12AU7 glow suggests that there's no heater current, and the green wires carry that current directly from the transformer. And you know that the heater winding of the transformer is working b/c the 6080 glows. So all of this points to a possible faulty joint on the green wires between tube sockets.  The problem might turn out to be somewhere else, but this is the first thing you need to rule in or out.

It might be helpful if you posted clear pics of each socket and of the solder connections of the green wires at each socket.

cheers, Derek

[Krishk]

Hi Krishk - I'd follow PB's advice here and really scrutinize the green heater wiring that runs between the two tube sockets.

No 12AU7 glow suggests that there's no heater current, and the green wires carry that current directly from the transformer. And you know that the heater winding of the transformer is working b/c the 6080 glows. So all of this points to a possible faulty joint on the green wires between tube sockets.  The problem might turn out to be somewhere else, but this is the first thing you need to rule in or out.

It might be helpful if you posted clear pics of each socket and of the solder connections of the green wires at each socket.

cheers, Derek

I've attached pics of the tube sockets. Please let me know if you need better pictures. I checked all the solder joints and they all seem stable however, please let me know what you think.

[Paul Birkeland]

This wire needs to be soldered for both tubes to glow.

You have some wires on the 9 pin socket with way too much jacketing stripped off, and that may cause shorts down the road. 

-PB

[Krishk]

Thanks for the advice I'll re solder that wire and I'll trim down any extra leads to prevent shorting, I'll let you know what happens.

[Krishk]

It turns out that was the faulty solder joint, after I applied more solder the lights for both the led and tube turned on. thanks for the advice!

[Krishk]

Hi Paul,
After getting the tubes relit again I redid the voltage tests and I found these terminals to be a bit out of the suggested range given in the manual. Should I be alarmed by these rather high voltages? The terminals not listed all came back within the range.
Thanks!

Terminal 2: 208 volts
Terminal 4: 208 volts
Terminal 7: 123.8
Terminal 9: 123.8 volts

[Deke609]

Just a shot in the dark here: you might want to (a) double check your mains voltage coming out of your wall outlets, and (b) make sure you wired the transformer for the corresponding voltage. It looks like your measured voltages are about 20% high. I imagine a mains voltage of 120V or more with a transformer wired for less than 115V would result in higher voltages.

cheers, Derek 

[Krishk]

I see, I used a different power strip to wire my transformer than the outlet I used to test the amp. Will that explain the difference I am getting? Thanks!

[Deke609]

I doubt it, but I can't say for sure. To take the strip out of the equation, try measuring the voltage coming out of the power strip.

[Edit: apologies - I misread your post. If you're not powering the amp through the power strip, and instead directly from a wall outlet, I'd measure the voaltge coming out of the wall outlet - that said, measuring both would tell you whether your power strip is putting out less voltage - in which case I'd say there's something wrong with it).

cheers, Derek

[Krishk]

I'm sorry, I didn't correctly identify that I used a surge protector, not a power strip, to figure out the voltage to wire my amp. Would a surge protector change the result?

[Deke609]

Dunno    Just measure it!

[Krishk]

I see what you mean, the voltages are the same and when I redid the powerline voltage test, the voltage came back as 123 volts. So I must have misread the multimeter. Anyways fixing the wiring should solve my high voltage issue then right? Thanks!

[Deke609]

Anyways fixing the wiring should solve my high voltage issue then right? Thanks!

My guess is "yes", but at the very least you'll be a lot closer 

cheers, Derek

[Paul Birkeland]

If you have 123V coming out of the wall and you wired for 120V AC, then I'm not worried about those voltages that you have which are a bit on the high side.

[Krishk]

Just to update, I reconfigured the transformer setup and now passed all my voltage tests. I tried the amp with a pair of zmf headphones and the amp sounds incredible! I have a very slight buzz when I have nothing playing, this is probably result to a faulty solder join right? Thanks for all the help with my build guys!