Anybody have a dead Champ 25

[Bill Moore]

I've been trying for quite a while, (with no luck), to find a PT for my Champ 25. I wonder if someone has a dead one, (not worth fixing), that may have a working PT? I would like to get this old amp working again. Thanks for any help.

[Enzo]

Is this the Champ 25 SE? Is the PT the 039043?

Does Fender have them?

The Champ25se has a B+ of 408v, bias of -41v, 6VAC for the heaters, and a winding for +/-24/16/8v for the solid state front end.

[Bill Moore]

Mine is not the SE model, but that is the correct Pt. No. My schematic showed a different No., but the copper on the PT has that no. stamped on it. Can you help? I thought I had one purchased from the guru, but they returned my Pay-Pal when they realized they were out of stock. They said it didn't look like Fender was going to build more any time soon. Thanks for the reply, Bill Moore

[Don Symes]

If you're more interested in getting the thing functional than in preserving its vintage integrity, replacing the 'correct' PT with a useable tube-oriented unit and adding a 24-0-24 tranny and some rectifiers and regualtors might be an option.

Enzo - was that 24/16/8 three sets of taps?

[Bill Moore]

Thanks for the reply, Don, the solid state portion of the PT is actually 19-0-19 vac, it increases to 24v after the bridge rectifier. There is an ac tap to the panel indicator from the + leg listed @ 19vac. Another tech has also warned me that the high voltage tap utillizes a full wave bridge, and no center tap, which I guess is unusual. He estimated that the input to the rectifier would be about 300vac, to gain the 408vdc. If you have any ideas, I'm all ears. Thanks again, Bill Moore.

[Don Symes]

Digikey has 18 and 20V transformers - should be close enough this is their parametric search : http://www.digikey.com/scripts/DkSea...S&Cat=35849111

You can the secondaries in series to get 18-0-18. All you need from there is a rough idea how many VA you want.

For the tube section PT, you have a 7025 with a 300mA heater and 2 6L6s at 900mA, each ... you need at least 2.1A of 6.3VAC.

For a push-pull pair of 6L6s making 25W - a Hammond 272BX (300-0-300 @ 100mA)? The Hammonds are designed for a Full-Wave recto, but not sure how they'll do for a bridge.

Would a 269BX (150-0-150 @ 75mA) be more appropriate?

[Enzo]

No, the 24/16/8 or whatever was the results of the one winding, as were the other voltages. It was one winding resulting in the +/-24, then drops to zeners for the lower volts.

The amp does not use a center tap, however you can use a center tapped transformer, just don't connect the CT to anything.