Problem with Bold setting on Trem-o-verb

[Mobius435]

Hi Everyone! New here and was wondering if you all could give me some help. I recently purchased a Trem-o-verb combo ('97) which has been a dream amp of mine for years. Everything seemed to work well until the other night when I was playing and the amp slowly started losing volume as well as sounding ultra distorted and flubby. Thinking it was possibly overheating I turned it off for the night. Next morning there was almost zero output unless the amp was cranked, in which case it was very distorted and the sound was intermittent.

I've done all the typical troubleshooting, i.e. tubes and switches, etc. Verified all tubes are good, but in testing switches I did find that the amp seems to work just fine when set to the Spongy setting (both channels) and the problem is most definitely isolated to the Bold setting. If I switch from Spongy to Bold it will sound fine for a couple of seconds before the volume slowly fades out and the intermittent sound/distortion kicks in again.

I've contact our only local Mesa authorized tech, but he seems to be very busy and we're having a hard time syncing up. I'm wondering if there's anything else I can try since I'm having a hard time getting it in for service. I do have some electrical experience and am very well aware of the lethal voltages that can be contained in the caps and take the proper precautions. I'm afraid it might be the output transformer, but hoping otherwise!

Any suggestions would be awesome though. Thanks!

 

[domct203]

How did you verify all tubes were good?

Are you using the tube rectifiers?

 

[Mobius435]

I ran the fx send (t-verb has serial loop mod) out to the fx return of a different amp and the preamp of the t-verb is working fine.

The power tubes are brand new JJ's from Eurotubes. I've tried them all in a different amp as well as running the t-verb with only 2 power tubes inserted for 50 watts, while trying all possible configurations with the power tubes. I even tried the Mesa branded 6l6s that it came with that were working when I bought it.

I made sure to test with rectifier tubes and silicon diodes too. Even ran the amp on silicon with the rectifier tubes removed. Same result in both settings.

I feel like I can safely say it's not the tubes at this point, although I really wish it was!

 

[Eevil]

I’ve heard some Tremoverbs had issues with Vactrols bad batch of those

In some amps I’ve had the fx return jack has been dirty/not connecting properly when there’s no plug and the symptoms have been similar. Not sure how the parallel fx loop is implemented but using jumper cable has been foolproof fix for that issue

 

[daveyf]

I had a similar problem on my Tverb, wherein the sound was very muddy and distorted. I replaced the rectifier tubes and re-set the power tubes. This fixed the issue. Even though you say that the tubes have been checked, I would definitely re- check those, particularly the rectifier tubes. Some of the new Russian tubes can be very iffy even when new. I also noticed that if I rolled in El84’s that the sound was again somewhat distorted and weak. A strong set of 6l6’s are the answer, hopefully in your case as well.

 

[Mobius435]

Unfortunately, I've tried 3 different sets of power tubes at this point, all 6l6. Mesas, JJs, and Rubies. Same result on all.

I decided to wave the white flag and called Mesa to fix it. Sending it off tomorrow, but they have an 8 to 10 week wait, ugh. Oh well. It'll be worth it, since this is an amp I've been waiting over 20+ years to own. I can wait a bit longer.

Thanks to everyone who responded!

 

[daveyf]

You did check the rectifier tubes? Anyhow, good luck with the amp.

 

[Mobius435]

Yeah, checked the rectifier tubes in a buddy's dual just to cover all bases. Checked the tube sockets by alternating a single rectifier tube running the amp with only 2 power tubes in 50 watts. Tried it on silicone diodes with the rectifier tubes completely removed too. Same story on all tests.

It's on its way to Mesa now though. Gave up on the local tech. 10 week wait, but I figure it's worth it since this is a dream/forever amp for me. If they can't fix it, nobody can.

Thanks!