What causes a power supply to fail?

[Supergumby5000 5,000+ posts]

Well, not necessarily fail.

My autotek4k is going in for repair due to power supply issues (and now blown mosfets)

I bought the amp used, wired it up, started my truck, and it worked fine (with nothing hooked up to the speaker terminals) I turn my truck off, come back 10 minutes later to tune with test tones, and as soon as i turn my truck on, i hear a slight pop, and ta da! my current issue. The amp still powers on and functions, but has a whine to it.

Anyways, what could have caused this to happen? I have 5600amp's worth of battery and a 250 amp alternator.

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[Trey803 5,000+ posts]

the voltage builds up if you dont have a speaker hooked up and it gets really really hot. This is how I blew my mbquart 1200.1

 

[chunky cumz 10+ year member]

the voltage builds up if you dont have a speaker hooked up and it gets really really hot. This is how I blew my mbquart 1200.1

seriously?

 

[Supergumby5000 5,000+ posts]

ttt

 

[Trey803 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.

This is just what I was told and would like to know if this is true or not also. As far as the amp not getting hot I don't know what if anything that means.

 

[Supergumby5000 5,000+ posts]

yeah, but i wasnt playing music.... I hadnt even put in the test tone CD yet.

 

[Trey803 5,000+ posts]

ive never heard of that before
what exactly gets hot?

As soon as i turned the truck off after the pop/smoke, felt the amp to see if anywhere on it was warm, and it was definately not warm to the touch, not even luke warm.

I guess if the voltage builds up quick enough this could happen before it started to get hot. Mine didn't blow for a couple of weeks before one day I smelled smoke and realized my amp was about to meltdown.

 

[Trey803 5,000+ posts]

yeah, but i wasnt playing music.... I hadnt even put in the test tone CD yet.

I had my HU sub output turned off when mine blew so there should not have been a signal into the amp either

 

[PaulD 10+ year member]

WOW ... that's all I can say

 

[teamquakecelica 10+ year member]

This is just what I was told and would like to know if this is true or not also. As far as the amp not getting hot I don't know what if anything that means.

That is the most nubi-ist thing I have ever heard... Absolute BULL SHIT

Voltage doesn't "build up" when the amp is connected to no load (not attached to a speaker) its the equivelent of you car idling.... does horsepower build up and blow up your engine?? I hope you answerd no to that question.... an amp with no load is simply drawing very little current maybe an amp or 2... its essentially doing nothing..

DO NOT LISTEN TO THIS CRAP!!

whoever told you that is a complete TOOL!!

 

[Saint211 10+ year member]

I had one of my profile ap 1040s hooked up with no load on it for almost 2 weeks and I play my stereo A LOT. Not a problem. Ive also bench tested hundreds of amps to verify they work or figure out whats wrong with them. Sometime for extended periods with and without loads. Hell, the other day I had an alpine mrp 1000 hooked up with no load for a longgggg time.

Never ever heard of this "problem" Sounds like a myth personally. Maybe something else caused it?

I dont even undertsand what you mean by the voltage building up. If you mean your electrical systems voltage, yeah high voltage can kill an amp, depending on design. Some will take only up to 15 or so volts while others will take higher. But you make it sound like the capacitors just keep trying to store power til they melt, which is totally crazy.

 

[Korn4Life 5,000+ posts]

Wow what a noob! Everyone knows its the Power Supply Fairy that comes at nite and ruins your amp

 

[Supergumby5000 5,000+ posts]

well, a lot of good learning info hear

but the question still doesnt have an answer! lol.

 

[Supergumby5000 5,000+ posts]

ttt

 

[Ford302Redneck 10+ year member]

The autotek 4k's had wine problems anyways.

I know of a few that that has happened to.