#1
I just made a quite big wipe, made mistake and plugged my 2x 8ohm's speakers to 2x 4ohm's amp inputs, and yea - I had from back of my amp smoke, smell and current out.
Yea i'm not carefully fool, ok, but my question is - is it for sure 100% broken thrash already, or probably it's repairable?
It is(was?) Mesa Boogie 50/50.

Speakers 8ohm's -> Mesa 4ohm's spekaers input (not reverse).
Last edited by Blazkowicz at Sep 30, 2014,
#2
I'm surprised anything bad happened at all. Mesas are pretty bulletproof like that, and especially in that direction. Is the amp working?
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Cathbard Amplification
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#3
Ok, I know the reason I plugged amp to wrong voltage current transformator (some chineese sh*t which i was running my preamp, instead of normal/better one).
It was max 100w and Mesa is 50/50, so the transformator is smelt like cheese, gladly i didnt burned whole house.
Unfortunelly Mesa also got burned something inside (i plugged to the other one transformator and its dead, no response).
Hope it will be repairable.

The smell is from transformator, Mesa don't smell like burned chicken, so maybe there wasn't much fire inside.
Last edited by Blazkowicz at Sep 30, 2014,
#4
Quote by Blazkowicz
Ok, I know the reason I plugged amp to wrong voltage current transformator (some chineese sh*t which i was running my preamp, instead of normal/better one).
It was max 100w and Mesa is 50/50, so the transformator is smelt like cheese, gladly i didnt burned whole house.
Unfortunelly Mesa also got burned something inside (i plugged to the other one transformator and its dead, no response).
Hope it will be repairable.

The smell is from transformator, Mesa don't smell like burned chicken, so maybe there wasn't much fire inside.

Check the fuses in the mesa, that would be my first guess. Like Cathbard said mesa amps are built very well and can handle thing a lot of amps can not.
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#5
Ok I'm not expert but that wire in fuse glass is broken (not continous from bottom to end) and there's little brown? spot on glass, so it's problably burned i guess?
#6
Quote by Blazkowicz
Ok I'm not expert but that wire in fuse glass is broken (not continous from bottom to end) and there's little brown? spot on glass, so it's problably burned i guess?

Yes it is burnt. replace it with the exact same type.

You also might want to see if the mesa has a multi tap feature where you could switch it to 240v instead of 110v. If it can you will need to get the correct fuse for that voltage.
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
Last edited by Robbgnarly at Sep 30, 2014,
#7
Mesa never have multi power taps, Rob.

Replace the fuse and see what happens. This time make sure it's into the right voltage. You may have gotten lucky. Chances are pretty high that you've fried something. Instead of 300 to 400Vdc, you've fed 600 to 800Vdc through it. I'd be surprised if you haven't fried a capacitor or two at the very least.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#8
I agree with Cathbard, replace the fuse and check it out, you might have gotten lucky, if the fuse blew quick enough. but if you fed it too much voltage, there is a more than good chance something else could have been fried as well, especially if it let the "factory smoke" out...that's never a good sign and just a fuse blowing should not result in visible smoke. At most when a fuse blows you'll hear a light pop and it will go quiet. If you saw and smelled smoke, chances are very good more than the fuse is blown.

And be very sure you replace the fuse with the exact same voltage and amperage fuse. DO NOT use one with higher amperage.

To explain the other comment Cathbard made, the transformer inside there takes 110V AC and changes it to 6.3V for the tube heaters, and anywhere from 300V to 450 V DC for the tubes to use. That's why it's very dangerous to open up a tube amp and tinker inside, the filter capacitors charge up and hold that same voltage, 300-450VDC, for several months after the amp is shut down. If you plugged it into 220, it sent double that voltage to the tubes, and the rest of the circuit, which can be anywhere from 600 to 900VDC...depending on the tubes, how hot it's biased, and so forth. You'd have to look at the schematics to know just what voltage it's usually supposed to have. My Fender Champ produces 350V, my Super Reverb somewhere around 400. Some other tube amps can produce as high as 500VDC in some cases, usually closer to 400-450 though.

In any case, you're dealing with some really high voltage, and if you plug a 110 amp into 220 good things are not likely to happen...I'd agree there is more than a good chance the fuse is not all that's fried...
Hmmm...I wonder what this button does...
Last edited by Paleo Pete at Sep 30, 2014,
#9
^^ I wasn't sure Cath, so many amps have a multi tap tranny these days that is why I threw that out there.
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#10
Not having a multi tapped PT is why hardly anybody outside of the US has a Mesa. They've got a collusion thing happening with their overseas distributors which pumps the price way up. Last time I looked they wanted something insane like $800 for an "export transformer" for the Mark V which makes buying a cheap Mesa from the US uneconomical, especially with shipping added in.
That's the only reason that I've never own a Mesa. And that's why in Australia, Mesas are as rare as an honest cop. It's a rort.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band