Mesa DC-5

[Kage]

I recently got a DC-5, has some issues and thought I'd see if anyone here might be able to shed some light. When I set up the channels like in the manual to try it out, the Rhythm channel is significantly louder than the lead channel (both masters on 4) and there doesn't seem to be any clean headroom on the Rhythm channel. To get it to clean up I have to put the gain on 1 and even then it breaks up if I hit the strings too hard.

If I pump the volume on the Lead channel it goes louder but it doesn't seem to be able to get even as aggressive as the Rhythm channel with the boost on. And one strange thing, on the Lead channel, the treble control works backwards. If I turn it down it gets brighter and darker as I turn it up. Any thoughts?

The tubes are new and it spent the last three months in the shop on some other problems. The screen resistor had to be replaced and the master volume on the Lead channel. There was another gremlin that had to be chased down (amp would play for a while and then cut out with nothing but a loud hum) but when he fixed that he ran into other problems and he just couldn't keep spending the time on it. He suggested I send it to Mesa and I may have to. Figured I'd at least see what I could find out here.

[mikeboone]

I'd send it to Mesa...

I just talked to Chris at Mesa yesterday. They are going to repair my Mark II C+. It has some intermittent vibration (fractured solder joints I'm sure) issues that I have methodically chased for months and cant seem to locate. Mesa's are cool amps but tend to be dense in construction and a pain in backside to work on.

They will run the amp through a "period correct" factory check-out. That will usually expose issues and they will correct them.

He said most times it is less than $250 since they have the know-how and have likely experienced the issue you are having and can fix it quickly. Look on their website and call the number. You'll likely have to leave a message, but they will call you back eventually.

[Gtr_tech]

I sorta like that amp. I'm not a fan of messy boogers at all, but that one sounds fairly normal. Best one I've heard yet.

[pdf64]

'on the Lead channel, the treble control works backwards'
Maybe the treble cap which feeds the hot end of the treble pot is open circuit. If you can id it, and get to it, trying bridging another cap of the same value across it's legs to see if that restores proper functionality to the treble control.
They can have densely packed PCBs (for guitar amps), but at least they have through plated holes. Peter.

[Kage]

Have a question, here is a picture of the inside of my amp. There is a white wire running from the power tube on the right to the board. Anybody know what that is? I found a few other pictures online but none of them had that wire. See anything obviously wrong?

http://home.earthlink.net/~corbeilt/MBDC51.JPG

[pdf64]

It looks like it's supplying a ground path or reference - not connected to the tube pins, just to the metal clamp that retains the tube socket to the chassis.
Doesn't look like it's original fittment, so I'd guess that it's been fitted in an effort to track down these gremlins.
Peter.