Hammond AO-28335-1 Power Transformer

[SuperTzar]

Hi everyone, this is probably a long shot, but I'm looking for any specs/info for the power transformer in an AO-50-1c amplifier. The part number on the transformer is AO-28335-1, and all I know is the -1 probably indicates it has a 120V 60 Hz primary.

I've searched high and low for a circuit schematic for that amp, but the closest I can find is the schematic for the 2000 series Everett/Hammond amplifier. I know the AO-50-1c was used in the Everett 3022 organ, so if there is a 3000 series service manual, it might have the info I'm looking for. Does anyone know what the secondary voltage might be? Is there a power supply schematic floating around out there?

If anyone has any information regarding the amp or power transformer, I would greatly appreciate it!

Thanks!

[David Anderson]

The only thing I could find via a quick search was the same Hammond/Everett schematic you found.

If the tube complement and general circuit are pretty much the same, then you should be able to work out the overall PT specs from the voltages and the current draw that can be calculated from the schematic. The main current draw will be the output tubes. If it's a dual EL84 amp, there were quite a few guitar amps that used two EL84s, so it might be possible to adapt a PT from one of those.

I assume you have a bad power transformer. Or do you have a PT and want specs on it?

[SuperTzar]

Thanks David. I have the complete amp, and the power transformer works fine, but the filter caps need replacing. I'd like to see a schematic of the power supply so I know which caps connect where, and so I know the replacement caps are of a sufficient voltage rating.

The circuit is similar to the 2000 series schematic online, but with a few different capacitor and resistor values.

[David Anderson]

I've worked on several rare amps where there was no schematic available. Can you not simply document what's there and replace the parts accordingly?

[SuperTzar]

That's my plan at this point, I've traced out the power supply circuit, and most of the caps are labelled. Still would be nice to have some specs though.