SMOKE!

[analogjunkie]

So i fired up my rockster with 6l6s and a 5u4 and it started to smoke. I unplugged quick and took out the tubes and fired her again, smoke.

I took the power supply board up and noticed the CT for the filaments was melted, then the filament taps themselves were melted. So I started over, figuring the PT was burned out anyway so why not keep trying. unplugged everything and back in again and fired her up and no smoke. voltages all look very good, and it sounds amazing.

should I be concerned? my power wiring is quiet neat and there is no exposure to ground on any voltage wiring. i know the edcor PT is supposed to be good quality but is it possible I got a bad unit? This thing SMOKED. TWICE. and is now working fine. thanks in advance!

[Ian444]

I have never read of an Edcor failure on the internet forums. If the filament wires coming from the transformer are melting then the problem is outside the transformer, not internal. Might be worth checking all your heater wiring, if it shorts again you might lose that transformer (or the heater windings at least). Hope you find the problem soon.

When you say filament taps, do you mean the heater wiring for the 6L6 and 12AX7 tubes, or the heater wiring for the 5U4?

[analogjunkie]

It is the center tap for the low voltage winding and the 6.3v leads. they melted but the smoke surely came from the PT.

[Zippy]

It is the center tap for the low voltage winding and the 6.3v leads. they melted but the smoke surely came from the PT.

If the leads melted, that indicates that they were carrying high current. An internal short would not load the leads.

Smoke comes from excessive current (IR heating) of the insulation on the windings.

Check your sockets for space between the tabs and wires. It is possible that you don't have much clearance between the ends of your leads and they shorted temporarily.

If you don't know what caused the failure, it will likely recur if you don't change something. I wouldn't just plug and play.