#1
So, basically I put this amp away for a few months in a spare bedroom. It was completely undisturbed the entire time. Now, the other day I went too power it on and...nothing... no lights, no noises...just nothing. At first I thought "ah no problem its probably just a fuse", but I replaced the fuse. Still nothing, and I even went to the local electronics store and bought a few more fuses just to make sure. Still no lights, no noises, nothing. I have a few extra tubes but not a complete set, i tried swapping them all around and I just can't get this amp to power on. The closest repair place is very very far from me, so before I take it in (which wont be for a long while because I am crazy broke at the moment). I though maybe id see if anyone had any ideas?

tldr; Mesa Boogie Mark IV (Version A) wont power on, no lights, no noise. Replaced fuse, swapped tubes, still nothing. Any ideas?
Last edited by MesaMarkIVA at Apr 25, 2014,
#2
Did you check the main power cable to make sure its plugged into the back of the amp properly? Can you try the amp in another room? Do you have kids? Could one of them have dinged it?

Thats a weird situation you have there

I would suggest checking the power tubes.. But even if they were seated properly, the amp should still power up. You just wouldnt be able to hear anything or very low volume.
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Last edited by Watterboy at Apr 25, 2014,
#3
Flick the on/off switch back and forth a few times. Maybe just dirt in the switch. Are you certain you have power at that outlet? Plug in a lamp and test it.
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#4
My money is on; faulty mains outlet, faulty power cable, not plugged in properly. Test all of them.
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#5
Wow, so I jiggled the on/off switch a couple times while leaving the amp on standbye and the lights started to turn on. After about 10 on/offs they went from nothing, to dim, then to fully lit!!! and then smoke starting coming from inside the chassis, smelled pretty gnarly. Only took a couple seconds before I saw the smoke and turned it off and yanked the plug... Damn, Im so heart-broken right now.
#6
The fact that the amp was on standby may be a blessing. At least the smoke wasn't from the HT side of things. It needs to go to a tech now to sort it out though. Something is badly askew.
Gilchrist custom
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Telecasters
Randall RM100 & RM20
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Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


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#7
Quote by Cathbard
The fact that the amp was on standby may be a blessing. At least the smoke wasn't from the HT side of things. It needs to go to a tech now to sort it out though. Something is badly askew.


Wonder if the caps died. Its about that time on that amp. With it sitting for a period of time it fits.
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#8
Well, the reservoir cap is often before the standby switch, so it's very possible. Not sure where it sits on the Mark IV but it's certainly a possibility.
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
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#9
Looks like the fan is tied to the power switch, at least according to the schem I have. The fan is run when the switch is on full power. No caps before the x-former aside from the ground switched one.

TS- where the fuses blown? Is the fuse blown now?
Quote by DeathByDestroyr
See, it's important that people clarify when they say "metal", because I pretty much always assume they are a Cannibal Corpse fanboi.
#10
When I first read the original post I was going to suggest the circuit breaker was tripped.

Strange situation you've got here, at this point I would highly recommend taking it to a tech as the problem is likely beyond your skills. Not only is the Mark IV a sophisticated amp, if you start poking around inside the amp without any proper knowledge it's possible to kill yourself from high voltage.

A pest of some kind (bug, mouse) could have crawled inside and shorted something in the power section, although I'm betting a cap in the power supply went to hell..
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Last edited by Flux'D at Apr 25, 2014,
#11
Could simply be the fan I guess. Is there some sort of failsafe tied to the fan perhaps?

Still, it needs to go to a tech. We can wax philosophically about what we'd look for in our workshops but that doesn't really help the TS.
Take it to a tech. There's a lot of shit going on inside those things.
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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
#12
Yup. Once opened it should be pretty easy to spot.

Those are some busy amps internally. Take it to a shop that works on Mesa's for sure.
Quote by DeathByDestroyr
See, it's important that people clarify when they say "metal", because I pretty much always assume they are a Cannibal Corpse fanboi.