Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TenderTendon on March 03, 2023, 03:46:08 pm

Title: 1974 Twin Reverb Transformer
Post by: TenderTendon on March 03, 2023, 03:46:08 pm

I was troubleshooting a power supply recently, when I remembered I had an old Twin Reverb PT in the basement. I had everything set up on the bench, so I thought I'd test it too. I definitely got some unexpected results. Is this transformer hurt, or is it possible that the center tap is that far off?

Title: Re: 1974 Twin Reverb Transformer
Post by: tubeswell on March 03, 2023, 04:02:06 pm

Try a simple VAC test with your multi-meter and no caps or diodes.


A twin reverb high tension winding for a 2-phase voltage doubler is 185-0-185VAC

Title: Re: 1974 Twin Reverb Transformer
Post by: sluckey on March 03, 2023, 04:08:32 pm

Looks like you have mistakenly used the bias tap for your center tap.

Title: Re: 1974 Twin Reverb Transformer
Post by: TenderTendon on March 03, 2023, 04:12:42 pm

Quote from: sluckey on March 03, 2023, 04:08:32 pm

Looks like you have mistakenly used the bias tap for your center tap.

Damn it Sluckey! You got me again. Testing again......

Title: Re: 1974 Twin Reverb Transformer
Post by: TenderTendon on March 03, 2023, 04:28:12 pm

Well, this is more like it...  335-0-335vac unloaded. 432vdc rectified and filtered. Good news is the transformer is good. Bad news is I have no use for it. Thanks again.