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Oh No! My Mesa Boogie M Pulse 600 has gone silent! Please help

Sutton

Sutton

Mar 3, 2005
635
1
40
Plainwell, MI
#1
Hey everyone,
I had a show last night, and brought my half stack in, turned it on and noticed that the volume was about 25% what I'm usually able to get. I switched out basses, switched out cables, I tried everything, and decided it was either My Mesa Boogie Mpulse 600 or my Glockenklang 2x12 cabinet. Because I was getting some volume out of it, and it wasnt distorted until I turned up my volume all the way, I think it might be the Mesa. Is this a problem that can occur if your preamp tubes die? I was always under the impression that preamp tubes dying would result in hissing and humming, not a huge cut in volume.

Mesa is closed until Monday, and I need my amp badly, as I play 3-4 shows a week. does anyone have any idea what could be wrong with it?
 
#2
hmm...that's not a lot of info to go on. More questions and maybe some tips.
* You say you switched out cables. Speaker cables too?
* Did you try a different speaker cab?
* When you turn your pots, are they gritty sounding?
* Try cleaning your effects loop jacks.
* Make sure your amp hasn't been switched to 230 volt by accident.
* Have you tried your amp way a different AC power source?
 
#3
I switched out Instrument cables, I havent tried speaker cables, as its a Speakon to 1/4" cable. I'll grab one of those and try that.

I also havent tried a different speaker cabinet. Mostly on the basis that I have no other cabinets to use. I'll try to find a cabinet and let you know how that goes aswell.

My pots have always sounded clean and without any scratching

Would the effect loop jack have anything to do with it, even if it wasnt in use? I have it set to footswitch, and I never turn on the effect loop, as I never plug anything into it.

There is no way to change it to 230V, so I dont think thats an issue.

But I'll call up our manager and get another cable and atleast try that. Are you suggesting that this issue can almost positively not be the preamp tubes?
 
#4
Sutton said:
I switched out Instrument cables, I havent tried speaker cables, as its a Speakon to 1/4" cable. I'll grab one of those and try that.

I also havent tried a different speaker cabinet. Mostly on the basis that I have no other cabinets to use. I'll try to find a cabinet and let you know how that goes aswell.

My pots have always sounded clean and without any scratching

Would the effect loop jack have anything to do with it, even if it wasnt in use? I have it set to footswitch, and I never turn on the effect loop, as I never plug anything into it.

There is no way to change it to 230V, so I dont think thats an issue.

But I'll call up our manager and get another cable and atleast try that. Are you suggesting that this issue can almost positively not be the preamp tubes?
Click to expand...

It certainly could be a preamp tube. Even if you aren't using your effects loop, it could still be it. Take a 1/4" plug and insert it/remove it several times in each jack of the effects loop.
 
#5
I tired my luck with the effects loop, no change. I wont be able to check the cables and whatnot until tomorrow when guitar center opens. But have you ever heard of a speaker cable still producing sound, just at a significantly lower volume? Because everytime I've had cable issues, it just cuts out or dies out completely...
 
#6
Sutton said:
I tired my luck with the effects loop, no change. I wont be able to check the cables and whatnot until tomorrow when guitar center opens. But have you ever heard of a speaker cable still producing sound, just at a significantly lower volume? Because everytime I've had cable issues, it just cuts out or dies out completely...
Click to expand...

no...I haven't. It is just standard operating procedure for me to switch out everything, when diagnosing a problem. Even if I switch basses and I still have the problem, I still check the battery in both basses.
 
#9
It;s not the tubes. I've changed both and the problem still occurs. I will check the effects loop switch and the effect loop jacks, as well as the passive input jack. I am sure mesa has heard of this problem and the solution probably is the same, but they won't tell you exactly on the phone other than say "send the unit in." They don't, however, offer a unit to use as a backup so I suggest getting a decent (eg. Hartke HA5500 or other) just to have around when and if the Mesa has to go in the shop. Love my 600's sound, though!
 

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