Mesa Boogie MK IV Problem - Big drop in volume after a while

[dandan]

I've owned an MKIII before and it never happened to that amp..

I was playing for about 20 minutes and the amps volume went down really low to the point where it sounds like pure fizz (and i was playing with my master volume @ 3 and output @ 3 so it was pretty **** loud)

i put it on stand by for a minute - and when i kicked the amp back in it got back its loud volume

could it be a tube problem in V1? i bought it used from Guitar Center and it had nothing but Groove Tubes in it (god knows how old the tubes are)

any help would be appreciated. Ill call boogie tomorrow and ask

 

[Boogiebabies]

Start with the V1 and test it wit a known good or new tube. If the problem persists, try each position after that with a know good or new tube. While your playing, wiggle the standby switch and master volume knob to see if you get a drop in volume just in case.

 

[geenads]

Had the same thing with my mark iv (A) about 2 weeks ago, I was cranking it pretty loud (master on 3.5, pentode, full) the volume dropped out of it and sounded "fizzy." I flipped it on standby for a second and it appeared to fix itself. It did it a couple of times during the gig. It also did it at last weeks gig once with master on about 2.5, triode, full power. The tubes only have about 10 hours on them..

 

[Boogiebabies]

Sadly, new tubes do not matter. They can be bad out of the box or after ten minutes. Some can last for years. The one amp that I have never had a tube problem with is the MK IV. Until I started using GT 12AX7M's in the V1 my other MK's would spit out a V1 often and a V3 or V4 from time to time. It's also very typical that the standby resets the tube. It's always great fun to turn you amp on and get no sound, then freak out about speaker loads.
The M is not impervious, but a quick standby flip gets them to stop crackling. I had one that sounded like a Fuzz Face right out of the box. GT warrantied about 10 of the early productions for me and I have had litte trouble since. The Ruby 12AX7C9 has proven to be extremely reliable. I have been running most of these for over three years or so in the C+'s.

 

[tommyhawk13]

Do yourself a favor & get something like this:
http://www.radioshack.com/sm-tv-tuner-control-cleaner-and-lubricant--pi-2103700.html
or this:
http://www.stringitup.com/tonelguitpic.html

I was ready to send my amp to a tech, but he refused to see it until I sprayed it down first. I had the same problem & this fixed it. It might not fix your problem, but it couldn't hurt.