RK series 1 problem: Low Power or Loss of Volume

asookazian · Dec 21, 2006

Master Volume stops increasing (cuts out and/or less loud) after turning master output pot past 50% or so. geofex.com debugging page talks about a possible faulty phase inverter tube which for this model is the V5 position preamp tube. Anybody know how the phase inverter works with the rest of the controls/pots?

I have recently replaced all the output and rectifier tubes with Mesas. The preamp tubes are not brand new and I was able to fix scratching sound by replacing V4 tube. The burning smell seems to have gone away but I think that was due to the old rectifier tubes.

Anybody had this problem before? I'm planning on re-tubing all 5 preamp tubes and if she's still having problems, taking her to Mesa Hollywood. She's definitely not as loud as she used to be...

P.S. How do you guys date Road Kings? My amp's serial # starts with RK-001. Is this a 2001 model?

Platypus · Dec 21, 2006

Definetly sounds preamp tube related, replace all 5 with known good ones.

asookazian · Dec 21, 2006

thanks i'll check out the FAQ

asookazian · Dec 21, 2006

i purchased 5 Groove Tube 12AX7C preamp tubes and removed the old ones and installed these new ones. Still has that BURNING smell and the power is weak (master output volume does not increase properly as expected).

I have a feeling I damaged one of the transformers (probably the output transformer) when I had the Line6 DL-4 running and it doubled the volume when I had the output at 6 and preamp at 6 on the ch. 3 and ch. 4.

I've heard reliability problems from my amp tech about the Marshal TSL 100 output transformer when you crank the amp. Same with the Mesa Road Kings? That's why I bought a Mesa, it's like a Lexus thing, you know? RELIABILITY!!!

All 13 tubes are brand new (all Mesas or GT's). It's not the tubes. Any ideas??? What is that **** burning smell!!!???

I'm taking to Mesa Hollywood this weekend if they're open...

asookazian · Dec 22, 2006

I just talked to Paul Patronete @ Mercury Magnetics and he said that it's possible the power transformer is dying. He said he gets this type of call a lot and referred me to a tech named Alan Cyr in the Los Angeles area. He said that the more you increase the master output/volume, the more current the power tranny needs to draw. When you play metal (like I do on this amp) there is not much rest to the tranny.

He said that Bogner and Soldano come stock with Mercury trannys, but Mesa, Marshall and Diezel don't. He also said that the burning smell may be from the dying transformer. He said that Mesas are not designed to be able to handle cranking the master output/volume very high (I had it around 6 on master and 6 on preamp ch. 3 or 4 the first time I smelled the burning).

The Mercury trannys come with a 10 yr warranty. Any advice on this whole thing?

Anybody routinely crank Mesa rectifiers past 50%?

Anybody had issues with stock Mesa trannys?

Anybody done mods with Voodoo amps to replace the trannys with Mercury's?

How does the Mesa warranty cover blown trannys?

Any help would be appreciated. He said that Mesa service will say that the amp is operating as designed (even with the burning smell???) b/c it seems to work ok at lower volumes with some fade in and out of sound.

Please don't say it's the tubes; I've re-tubed all preamp tubes with GT 12AX7C and all the others with brand new Mesas. Fuse never blew.

P.S. Mesa Petaluma office is closed starting today until Jan. 2nd (that's shitty customer service, honestly) I called them and got that message on the greeting.

:evil:

Platypus · Dec 22, 2006

Not calling the MMOT guys liars but I've never had a problem running my rectifier and I crank the living piss out of it with a power soak DAILY for a year straight now... something is up with the amp, possibly the OT, but it's a poor practice for them to make a blanket statement like that... especially when they're trying to push their own product :roll: :roll: :roll:

Good luck with what you find, just don't believe slimey sales tactics like that.