Unwell 1959 Superlead

[Wicksy]

Hi guys, i have been performing a little maintainence on my old '77 superlead. I cleaned the pots and jacks, replaced a 100nF cap with the correct 100nF Mustard and replaced a busted bias pot. I also installed 1 ohm resistors on the cathodes of the EL34s to facilitate biasing. However, i now seem to have a rather major problem. I switched the mains switch on (standby still "off") and immediately the heater wires between some of the power tube sockets started to smoke and are now charred. I didnt push my luck but i quickly measured about 4.5VAC across one of the power tube sockets heaters...not good.

I figure i might of burnt a few wires when i was soldering, which might be causing a short. I'm going to tear out the power tube heater wiring and replace it for good measure and test the filament winding on the power transformer.

Has anyone got any other suggestions?

[Alexo]

You can test if you've shorted the heaters thus:

Disconnect the leads from the heater supply on the pt to the first tube socket they go to.

Test for continuity between the leads, there should be none at that point, if you get continuity, you can go down the line, disconnecting each socket till you find the right one.

If you have no continuity between the two leads, something else may be fishy...

[kd]

Make one of these and hook your amp up to it before you turn it on again. If there is short, it will save your PT.
http://www.geofex.com/Article_Folders/SPO_Test.htm



Ken

[Wicksy]

Cheers guys!