Egnator 40

[Perkinsman]

I have one that blew a mains fuse & after replacing it, blew the one on the plug. I’ve read that these have power transformer problems. How do i check the transformer to know whether it’s bad?

[The Dude]

Do you have a light bulb limiter? If not, now's a good time to build one. I'd first pull the tubes and fire it up on a LBL. It could just be shorted/bad tubes. If you suspect the transformer, unhook the secondaries and fire it up with only the primary hooked up. Does the LBL go bright or does the fuse blow again?

[Enzo]

The question to ask is how do I find WHERE the problem is.

[Perkinsman]

I tested the tubes in my BK tester. Power tubes were fine, but the 3 ax7s were weak. I replaced the blown plug fuse, detached all of the secondary wires, pulled all tubes, plugged into 8 ohm speaker & powered on & was happy to see that it didn’t blow any fuses. Was this the correct procedure to determine whether the PT is bad?

[Perkinsman]

I put the tubes in, replaced the ax7’s & started it up on my variac with current meter. The current rose quickly at as I slowly raised the voltage so I powered down. How do I find where the problem is from here?

[The Dude]

Well, if you unhooked all of the PT secondaries, it doesn't matter if there's a speaker, tubes, or anything else. The amp is not powered. If the fuse held, I'd next check those secondaries to see if you have ACV there. You should, but verify. Be careful not to electrocute yourself!

[Perkinsman]

[QUOTE=The Dude;551475]Well, if you unhooked all of the PT secondaries, it doesn't matter if there's a speaker, tubes, or anything else. The amp is not powered. If the fuse held, I'd next check those secondaries to see if you have ACV there. You should, but verify. Be careful not to electrocute yourself![/QUOTE

Check AC on each of the secondaries with the tubes out and the secondary wires pulled?

[The Dude]

Yes just the secondary wires hanging there unhooked from the amp. Then check for voltage coming out of the tranformer (wires). We are only testing the transformer- not the amp. Tubes in or out- it doesn't matter.

[Perkinsman]

Yes just the secondary wires hanging there unhooked from the amp. Then check for voltage coming out of the tranformer (wires). We are only testing the transformer- not the amp. Tubes in or out- it doesn't matter.

What do you mean "voltage coming out of the transformer? Isn't that the ACV I'm checking the 2o's for? Or do you mean another set of wires?

[The Dude]

......Isn't that the ACV I'm checking the 2o's for?......

I'm not sure what that means? But, yes check ACV out of transformer with secondary unhooked.

[Perkinsman]

I'm not sure what that means? But, yes check ACV out of transformer with secondary unhooked.

I think I misunderstood your message. I'll measure the 6 secondaries (2o's) & report back.

[Mick Bailey]

What do you mean by 2o's? Not come across that term before.

[Dave H]

What do you mean by 2o's? Not come across that term before.

It's a new one on me too. 2o's = secondaries

[Helmholtz]

I'll measure the 6 secondaries (2o's) & report back.

And pay attention to measure between the corresponding wires of each secondary and not wrt to ground/chassis.

[Perkinsman]

[QUOTE=Helmholtz;551518]And pay attention to measure between the corresponding wires of each secondary and not wrt to ground/chassis.[/QUOT

You mean measure ACV green to green, red to red & yellow to yellow?