Toroid transformer in Hartke HA3500a dead

[spider]

Hello

I have a little problem

I buy a Hartke HA3500a with a dead toroid transformer ( i have this information before i buy ) and i try to find a equivalent, but it's not really easy because secondary is not very standard

WP/QCI T20073935030 TOP CHEERS

59v -0- 59v
0-189v
0-10.9v
23.4v -0- 23.4v

I think it's possible to use more than one transformer, but it take more space...

Before this model ( HA3500a ) hartke not use toroid transformer for the standard model 3500.

It's very strange because all fuse are OK, but the transformer smoke.

Any idea, experiences about that ? Thanks a lot !

[Amp Kat]

Are you sure the tranny is gone. The Toroids will sometimes loose connection on the wires coming out that have the coated copper around them. If you strip it back with some cutters you will see the true copper to connect to. If it's hooked up something else could be dragging it down making you think it's bad.

[Steve Conner]

I'll bet that the 189V winding, or one of the other low current windings, has shorted out. Because they have thin wire, the short circuit current isn't enough to blow the fuse.

Hopefully, the 59-0-59 drives the output stage and is the only real high current winding, so you can replace the whole mess with one large off-the-shelf toroid. The exact voltage isn't critical, and units with two identical windings of 50, 55 or 60v can be bought off the shelf or on ebay.

The other voltages could be got by a combination of things like winding your own wire onto the toroid (should work fine for the 10.6V, maybe the 23.6, you'll need a lot of patience for the 189!) and using two small transformers back-to-back, or one small transformer backwards to step up one of the windings you added to the toroid.

But do check all the stuff Big Kat mentioned, to make sure it really is the transformer. If it's smoking, it almost certainly is damaged, but maybe something in the amp blew and shorted one of the low current supplies, rather than the tranny itself shorting out.

[spider]

Thanks Amp Kat and Steve

Yes, i sure the transformer is dead



I test with ohmeter and the problem is the one of the primary is dead, other seems like OK, i find values between 0.4 and 3.1 Ohms. But it don't change the problem, this transformer must be replaced.

Maybe 3 transformer would be find to do this, but the voltage values are not really simple to find. Ok for the supply of the amplifier ( 60v )

The other problem is if i would build myself a transformer(s) i need to know the power of each sections of transformer, it's possible to find with another Hartke transformer and mA Grip.

The cost of this tranformer in France is expensive ( 200-220 €... ) and i would replace it but i think 2 or 3 tranformers or another build specialy by another manufacturer with my specification is more cheaper... i hope lol

It's strange that nobody already replaced this one, but thanks for any idea or help

[Enzo]

200-220 might seem expensive, but it would drop into place, connect up immediately and your project is complete. But if you spend 150 on several transformers, using up hours and hours searching for them, mounting them, calculating new wiring patterns, what have you saved? My labor has a value to me.