Why did my amp blow????

[Trey803 5,000+ posts]

MBQuart pab 1200.1

So......I dont have the sub hooked up but havnt had the time or tools to take the fuse out of my distro block to the amp. The amp has 2 fuses on it and I thought taking one of them out would stop it from turning on. I noticed it still turned on with one fuse in but got really really hot(I havnt ever really touched it to feel temp. until now) I put the the fuse I took out back in and was like ok Ill leave it be. The speaker wires are taped up. I have no allen wrenches right now which is what I needed to remove anything basically. So I keep an eye on the temp and when I turn my HU on the amp gets really really hot so after a while of no music I braved it (under the assumption it always got this hot) and played some music. The only way I had to turn me sub amp off was to turn my cd player off = no music. A couple of days go by and nothing happens so I figure my amp just runs hot. To be sure I even turned the gains all the way down. I got in today and turn on my cd player and then the bad smell....turn around and smoke comin out. Im not too mad b/c I do car audio for the intellectual challenge not bragging rights and now it gives me something to try and fix! I will take pics of internals ASAP but my main question is why the hell would it have done this???? The speaker wires are both comp. taped, gain all the way down, and sub turned off on cd player.

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[Trey803 5,000+ posts]

cliff notes:

no sub hooked up

no tools to unhook amp

electrical tape on ends of speaker wire to prevent problems

amp still connected but gain all the way down

sub option turned off on cd player

speaker wires taped very well

amp gets very hot but never smokes

today for some reason started smoking

 

[TurdFergueson2 5,000+ posts]

what size is the wire going to the amp? and what size fuses are you using? I would say never ever mess with the fuses on the amp unless ou know what you're doing. Sounds like it's time to try another amp. Which one are you considering?

 

[Trey803 5,000+ posts]

No offense but wires and fuses are the correct size

O this amp has worked flawlessly with my FI Q.....and even for a very long time w/o it hooked up. What could have caused it to blow so suddenly? Im not even sure if it is blown I havnt looked at the internals yet but smoke usually means goodbye

 

[Trey803 5,000+ posts]

bump

 

[Team WP Bill 10+ year member]

Sounds like an internal short

 

[Trey803 5,000+ posts]

O and my Alpine amp that is running from same power and ground through distro block is working 100%

 

[Trey803 5,000+ posts]

no ideas? Im wondering if having nothing hooked up to the outputs has anything to do with it.

 

[Ed Lester 10+ year member]

so you were playing music with the amp hooked up but no sub?

If thats the case what happened was the rail voltage built up without a load and cooked your MOSFETS on the output stage.

You should never run an amp without a load hooked up.

 

[Blinkdogo2 10+ year member]

sounds possible ed lesster

 

[Louisiana_CRX 5,000+ posts]

so you were playing music with the amp hooked up but no sub?
If thats the case what happened was the rail voltage built up without a load and cooked your MOSFETS on the output stage.

You should never run an amp without a load hooked up.

x2

 

[99grandprixGT 5,000+ posts]

shit all u had to do was take out the remote wire.

 

[headless 10+ year member]

huh; i've never run an amp without a load...but out of curiosity,

1. Would this happen even if you don't actually send a signal to the amp? He said he disabled the sub outputs on the deck...

and

2. Does this mean if you were to set gains using a DVM you'd need to measure voltage with the speaker connected? I thought that wouldn't work.

 

[oldschool4me 10+ year member]

shit all u had to do was take out the remote wire.

thats what i was thinking. cut it if you had to. unplug the rca's as well.

 

[muskyhunter567 10+ year member]

wait so if your never supposed to run an amp without a load how are you supposed to set your gains with a dmm? i thought you were supposed to unhook the subs and then hook up the dmm? and i have a mbquart 4.100 and that thing gets pretty warm also