63 vibroverb reissue--reverb problem

[dannymac]

Hi folks---I have a 63 Vibroverb with a howling/distorting reverb issue. When the Reverb is "on", there are certain notes that produce a distorted buzz that sustains. Also, the amp will produce a feedback type hum when the reverb is engaged. not sure where to start-- the amp has none of these issues when the reverb is not on.

The amp is stock as far as I know, except R58 was changed from a 1k to a 3.9k in order to correct the bias issue, and the speakers were replaced with Jensen C10q's. also, the reverb driver and recovery tubes are both new. (V4, V5)

Any thoughts? I am not an amp tech by trade, but feel comfortable using a multimeter and a soldering iron, and understand the safety issues when working on tube amps.

any help troubleshooting this would be great!! thanks so much--

d

[Jazz P Bass]

What are the chances that the reverb pan wires got reversed?
If not that, the reverb transformer itself may be going.

[dannymac]

that certainly could have happened. The Reverb leads are not marked or colored as to which is which. the tank is labeled input and output with the jacks being red and white.

I'm not sure how to tell which lead is which?? how do you test that?

I could just reverse them and see if it helps--will try and repost--

[überfuzz]

Hi, I guess I should say welcome!

First of all, you can flip the reverb cables around and see if it helps. You might even try the amp without the reverb connected, just to rule out as much as possible. Lastly, have you done the basic troubleshooting, switched tubes, checked for bad grounding, etc?

Edit, I just realized that you're tinkering with a reissue. I'm not sure grounding is an issue with those at all...

[Jazz P Bass]

.

I'm not sure how to tell which lead is which?? how do you test that

The wire that makes the amp hum when you touch the tip is the return (out)