Blown Fuse: Mesa Boogie Dual Rectifier Multi-Watt (Should I be worried?)

[Mike_Blaszk]

Hey guys,

I purchased my Mesa Boogie Dual Rectifier Multi-Watt second-hand a little over a year ago and its been a great amp for me since. However, I figured that the thing needed a full tube change as the existing set had been over a year or two old prior to my purchase and, tonewise, things had recently started to take a change for the negative; particularly after the amp had been on for over 45-60 minutes. So, I replaced all of the preamp and power amp tubes with Mesa glass (STR440's, 12ax7's and 5u4gb's). This had everything running back better than ever today except for the fact that, at about the 1 hour mark, the amp suddenly got very noisey (lots of feedback), the volume suddenly dropped and the amp shut off. In fact, it wouldn't turn back on despite the fact that all of my other electronics were still in working order. Admittedly, this had never happened to me before and I was a little freaked out, but I eventually put 2 and 2 together and replaced the amps main fuse. Afterwards, the amp turned back on and I monitored the inside of it for a minute prior to flipping the standby switch and watched things for another minute without issue. Should I be concerned? Is this something that I should get checked out?

Appreciate any help/suggestions. Thanks,
Mike B

 

[the recluse]

When I've had fuses blow, it's usually been due to power tube issues. Either Bias was off, or there was a defect in the tube. I'd replace your fuse and see if the old power tubes cause it to blow again. If it does, you may have a bad tube in your new set.

 

[Mike_Blaszk]

Started the amp up fine without blowing another fuse and played for 30 minutes. However, the amps volume has dropped significantly and theres quite a bit more interference (Im picking up some kind of Punjabi radio station). Any ideas?

 

[the recluse]

Still sounds like possible tube issues. Easiest way to trouble shoot is to start swapping with known good tubes. If you cycle through all of them without eliminating the issue it's time to go to a tech

 

[Mike_Blaszk]

Atleast for the time being, the issues seem to have been resolved by replacing two of the power tubes (only one appeared to show signs of burning/black marks and functioning quite dimly upon closer inspection, but I replaced the set). However, I'm also going to have to look over the preamp tubes at some point because the amp sounds quite different with the FX loop engaged now (could be a cable or something else too). This is such a bummer to deal with when it happens lol; especially randomly losing a power tube during a time of shortages/price hikes. And theres still the possibility of an underlying issue that causes things to blow again down the road.

 

[Mike_Blaszk]

I'm driving it over to a certified Mesa tech to give it a once over to negate any potential issues, just in case. I'll let everyone know what the verdict is when I hear back.

 

[Mike_Blaszk]

Everything's fine with the amp. Looks like a tube failure blew the fuse. Once the fuse and blown tube were replaced, everything appears to be back to normal.