Reverb Problem 1977 Twin Reverb

[plexi50]

I have a 1977 Twin Reverb that had a bad reverb transformer. I have installed a new transformer and have the following problem:

Without the tank being installed i have a loud squeel at half pot CW and also the reverb pot seems to be working more like a volume pot

The primary voltages on the reverb tranny is 435VDC and the secondary is 431VDC. I would think it would be lower on the secondary

Cathode voltages on  V3@7.2 VDC & V4@2.2 VDC





No reverb when the tank is connected. Any clues?

[eleventeen]

The **SECondary** of the reverb tranny is showing big volts?? I hope like heck you mean the "tube side" = blue (vs the B+ side = red) of the rev trans shows big volts. Those are both on the primary side. It's correct that there's only a single-digit (or so) voltage difference between those primary red-blue leads.

You mean you are sending 400+ volts to the reverb can?? Ay caramba. A Fender reverb tranny is nothing more or less than than a fairly ordinary 5-8 watt SE output transformer. With nothing plugged into the reverb send jack you should have nothing, zero on the reverb trans secondary. One end (blk) is grounded, the other (green) goes nowhere until something is plugged into the send jack. Do you have that ground = black in place?

Check coil continuity on both ends of the reverb can. That includes checking VERY carefully the integrity of the solder joints and indeed, all aspects of the teeny wires at the RCA plugs within the rev can. That is 65% of ALL reverb problems as far as I'm concerned.

Usually, changing the 12AT7 driver does nothing, but in this case it's worth trying another tube, plus same for the recovery tube.

I'm wondering if the transformer going bad took out some surrounding components. WHAT was bad about it? Pretty rare to see those go bad.

^^^^^^^^^^^^^

If, when the Rev trans failed, it applied primary volts (circa 400 vdc) to the secondary (supposed to be like a speaker) it might have done some fairly wicked things. If it didn't blow the mains fuse from overloading the amp power supply, it probably would have turned either the transformer secondary OR the reverb send transducer (or BOTH) into fuse(s) and fried them with extreme prejudice. I continue to believe that would be an extremely unusual failure mode for that transformer. But if it happened, it woulda done some damage.

You have to go right away to checking continuity on the reverb send transducer and all the wires connecting to it. And I would definitely take the "bad" reverb tranny and see if there's a short between any combination of [red-blue] and [grn-blk]. That should be a fully open connection.

[plexi50]

eleventeen your great! Look at what i did

First pic is the Fender way

Second pic is my way

I have my dunce cap on today / Ground wire is soldered to ground now. Beautiful reverb. Thanks*