6G6B build - bad power transformer????

[Greg_L]

I've built a 6G6B Bassman into an old junky solid state combo. I've run into trouble right off the bat.

I'm not getting any bias, heater, or HV out the secondary of the PT. I've got it on a variac and a light bulb limiter. At 70 VAC input I'm getting that voltage to and through the power switch, but then nothing coming out the secondary side of the PT. Nothing on the pilot light. Nothing on the bias feed. The center taps are on a confirmed good ground. The light bulb limiter is not lighting nor has the fuse blown. I'm just getting nothing out of this PT.

I'm also getting continuity to ground through one leg of the HV secondary taps.

It's a Classic Tone that I've been sitting on for a few years now.
40-18005.pdf

My wiring goes...IEC receptacle hot > fuse tip > fuse sleeve > power switch > transformer primary > transformer primary > IEC neutral.

Any ideas? Am I just too wrapped up in it and missing something here?

[loudthud]

Unplug from the Mains and Ohm across the power plug. Any continuity when you turn the power switch on ?

[Greg_L]

Unplug from the Mains and Ohm across the power plug. Any continuity when you turn the power switch on ?

Yes there is. Open with the switch off, about 1.5 ohms with the switch on.

[loudthud]

Seems kinda low ... disconnect one side of the primary and Ohm the primary.

[Greg_L]

Well I'm sorry for the false alarm...it seems to be working now. I disconnected the two secondary leads from the diode rectifier and the bias wire. Powered it on and got voltage on those wires and the pilot light/filament string came alive. Reconnected everything and things are working normally. I guess I just had a bad solder joint on some of this stuff. DOH!!!

Now I'm getting 490 VDC unloaded on the first stage caps and max negative bias voltage at -62 VDC. Heaters purring along at 6.5 VAC. So far so good.

[J M Fahey]

Cool.

With normal to lowish resistance primary present, current can go into it (I mean current, not voltage) which in due time *must* induce voltage in secondaries.

You may have one open, of course, but all open at the same time? Not impossible either but highly unlikely.

[jack briggs]

I have this same tranny in a build I did last year. On mine the CT wire came out of the bell housing before the trans was installed! Had to remove bell cover and resolder the lead. Don't know if you could have the same issue, but I though it worth mentioning.

cheers,