Fifty/Fifty Implosion...Help!

potus2028 · Nov 1, 2009

I was running my Fifty/Fifty pretty hard the other day (around 6 on each channel in high power, for over half an hour), when all of a sudden, the AC kicked on, there was a huge did/surge in the current, and there was a fizzle/pop from the amp. I saw it as it happened and immediately turned the amp off. I found the fuse blown, and thought that was all it was...replaced the fuse and went to turn the amp on today to be met with more fizzle, and more awful "oh sh*t!" smell of fried electronics.

I opened up the case and found the board toasted and several components burned out right in front of where the big transformer connector clip attahces to the board. Looks like two big resistors and maybe more. The board is actually a bit charred/scarred.

Anyone have any clues? Is the tranny fried, or did the dip/surge "only" toast these components???

The amp was plugged into a furman power conditioner when this happened. I watched as the current lights on the Furman went from 120+ down to 80 or so as this happened...

I'm kinda tweaked about it because now I have a $500 piece of gear that is either worth $0.02, or is going to cost too much to fix to be worth it...

fishyfishfish · Nov 1, 2009

Nothing major. I would send it to a authorized Mesa service center just for peace of mind. My best guess is that you fried some grid resistors or a varistor that protects the power section of the amp from being totally ruined. My old Lonestar was plugged into 220V once. It cost more in shipping than to fix the amp. Mesa's are built more than solid, but some things are out of control. You might need some tubes as well, but let the tech tell you that.
Keep us posted!

Oh yeah, do you know anything about the Suhr Mini MixII?

potus2028 · Nov 1, 2009

I appreciate the upbeat response...I'm really freaked about this. The hardest part is going to be finding an authorized Mesa tech in my area...

The tubes all look good - nothing visibly burned out inside any of them or anything. I'm going to have to call Mesa tomorrow to find someone near me who can look at it. I have to call them anyway to try to get a few replacement pots for my Nomad 100 Head.

It just LOOKS so bad inside, all burned up and stuff...makes me sad...

fishyfishfish · Nov 2, 2009

Might be the Varistor , a disk filled with metal oxide that protects the amp from power spikes. When that thing goes it makes a mess. So do other diodes and resistors when they 'Blow up". They go down in line to protect the rest of your amp. I mentioned a Mesa Service Center because they would have all the schems and would hopefully do the work to Mesa's spec. When my LSC went down in looked like an ashtray flipped over on the board. They will clean all that up good as new. Good luck!