Strange reverb problems, Help, I'm going crazy!

[dragonbat13]

OK I will try to make this as brief as I can.

Reverb not working for a few years. I just left the tank disconnected.
Decided to fix up my amp(Twin Reverb 100 Watt). Swapped in all new tubes. Did a complete cap job, installed a blackface kit. Converted to adjustable Bias. Amp sounded great after I discovered a cathode resistor problem on the reverb driver tube. I had not tried the reverb yet, The amp was down on power on the reverb channel. Anyway I hooked up the tank just to see what happens. It was working. Then As I start to turn the amp up the reverb would go out. I started checking the circuit to no avail. Then I scored a organ amp that had reverb and used the tank from that. It doesn't have a bag. I was just seeing if the original tank had problems. It worked. Then As I crank the amp up the reverb went nuts with all kinds of feedback and noise so I turned the reverb all the way down. The amp still sounded fine. Turned down the amp and tried the reverb again. NO Reverb, so I got mad and wacked the tank, you could here the springs but no signal from the guitar was coming through, so I Hit it harder (troubleshooting?!), started working. I also twisted the cables back and forth and the reverb seemed to be more reliable at high volume. I am thinking that I need a new tank but I don't understand why high volume doesn't work but low volume does until you crank it. I did try the reverb tank on a table outside the amp and you can crank it louder but not maxed out.

I am sorry about the long writting but how else can I explain this?

Any suggestions would be GREATLY appreciated.
Thanks

[rfgordon]

I just finished a build of an amp with reverb, and experienced somewhat similar problems. I could hear reverb "boing' but no guitar in it, and the verb driver was drawing HUGE current. Turns out it was a bad verb xfrmr--brand new, mind you. Swapped it out and all was verbolicious.

I'd check the plate voltage on the verb driver. If it's stupid low (my xfmr was downstream of a 100k resistor, and above the resistor it was 325vdc, but on the plates (after the resistor and xfmr) it was like 6vdc. The thing is, just checking the pri/sec with a meter didn't tell the story, but there was obviously a short in there.

Reverb xfmrs are cheap, so try a new one. Also, be mindful of the input impedance on the tank. If your verb xfmr was iffy, a bad mismatch may have done it in completely. Here's a link to a table of reverb tank codes.

http://www.ampwares.com/reverb_codes.html

[dragonbat13]

Thanks. I was suspecting the transformer at one point but when it started working some of the time I thought maybe it was ok. I will check it out when I get home from work next week.

Thanks again!