2nd Mesa III Guru question..

[youthinkyourfish]

First... let me say that I have finally stepped off the plate and joined the ranks of the hardcore amp gurus.. ...

I just got my first major amp in, a Mesa Mark III .. wooHOO !!...

I have been playing a small POS mini-marshall for the last three years and before that, nothing.... (at least nothing worth at all mentioning )... and I am as green as green can get with these types of amps since I have NEVER owned anything like this so appreciate you bearing with me....... but, I can learn...


So hear goes..... I just turned the amp on, (after speaking to JGCable how to hookup up the Framus 4x12 16 ohm cab I have.. thanks Dude...(got a Cobra on the way)... and christened it with Big Red playing 'Lay It Down'...just awesome even though I had nothing really dialed in yet.... ........
....then the trouble started....

So my first question is, after about 15 minutes of playing at about Master Volume 1.2, the volume started to drop real low, then proceed to come in high then drop low again... (it stayed mostly low).. Would this constitue bad tube(s) and if so, can I start a troublshoot procedure by swapping tubes around???

My 2nd question's answer may take care of the 1st qustion.... Should I get replacement tubes and if so, from EuroTubes.com to replace the current ones I have and if so, what tubes should I get as in 6L6 or EL34 or a combintion of both and also get replacement 12AX7 tubes, the little ones?? OR, should I get the replacement tubes from Mesa.com and again, get the EL34 or 6L6 or a combination of both and the little tubes?? This question of course may mean nothing if swapping tubes will work but I am of the mind that starting fresh with a fresh set of tubes might be the ticket here... (especially since there seems to have been alot of moisture on the bottom of the amp at sometime)..

Thanks very much for your help and I will probably be asking a ton more questions.... .... remember, totally green at this...



Givin' Your Fish Away

[jgcable]

It could just be some dirt in the volume pot. Try spraying the pots with contact cleaner and... with the amp off!!!.... turn the knobs their full rotation. It could also be a dirty effects loop jack. Clean them too. Spray a quick shot of contact cleaner in them and plug in a jack several times.
Don't start swapping tubes yet bro!!!

[youthinkyourfish]

Hey JG... contact cleaner... don't have any... will head out and get some..,, any brand, style, quality, you recommend?.... thanks for the input.. will keep you updated..



Fish Talk

[jgcable]

Hey JG... contact cleaner... don't have any... will head out and get some..,, any brand, style, quality, you recommend?.... thanks for the input.. will keep you updated..



Fish Talk

GC Electronics makes a good cleaner. It doesn't really matter. Go to Radio Shack. They have it.

If you think its tubes just swap around the preamp tubes first and see what happens. Try putting the amp on 1/2 power and see if it stops. If it doesn't,then swap around the power tubes providing they are all the same. Swap the inners with the outers.

[youthinkyourfish]

Update on this issue. Used the contact cleaner on all knobs and switches... basically overhauled the amp, both internally and externally...(damn, it cleans up nice)... then, tried swapping tubes.... nothing....
I figured I'd done everything at this point other than take it to a service center (which I'm not willing to pay someone what I can do myself).. so gave Mesa a call; not much help other than recommending I change tubes and to buy Mesa brand.... thoughts anyone?

FYI...I've heard stuff about JJ Tubes, EuroTubes and biasing adjustments may need to be done when changing tube brands.... (it currently doesn't have mesa brand tubes in there now).... any help would be appreciated.... thanks guys...

(Do I wanna get this thing running or what??!...)

Fish

[sworn_enemy]

Update on this issue. Used the contact cleaner on all knobs and switches... basically overhauled the amp, both internally and externally...(damn, it cleans up nice)... then, tried swapping tubes.... nothing....
I figured I'd done everything at this point other than take it to a service center (which I'm not willing to pay someone what I can do myself).. so gave Mesa a call; not much help other than recommending I change tubes and to buy Mesa brand.... thoughts anyone?

FYI...I've heard stuff about JJ Tubes, EuroTubes and biasing adjustments may need to be done when changing tube brands.... (it currently doesn't have mesa brand tubes in there now).... any help would be appreciated.... thanks guys...

(Do I wanna get this thing running or what??!...)

Fish

Email Doug at dougstubes.com and tell him what type of stuff you like to play and what sound you want and he'll recommend a tubeset that will sound great and will work in your amp. It won't have to be biased.

[Twisteramps]

dirty fx loop possibly. Put a guitar cord in the fx loop from in to out. I know you cleaned the jacks, but try a guitar cord. The jacks may need to be replaced - the cable will 'hard wire' the jacks for now.

Pete

[442w30]

On my Marshall with a volume fluctuation problem, I just needed to reseat the PI (phase inverter) tube and it cleared up my problem. I got a spare set in case it acted up again. - other suggestions here are good.

[Deneb]

I do want to say that, if you use tuner cleaner, to make sure it has lube in it.

[jgcable]

So...... what the heck happened???