# Why did my amp catch on fire ? lol



## zblee (May 18, 2010)

Well I just recently found some good deals on craigslist for some amps and subs and i was testing them to make sure they work.. they were all good until i got to my Rockford Fosgate Punch 500S.. this amp was in pristine shape .. but this is what happened, to test the equipment I simply connected some extra 8 awg to my distro block ( power and ground ) to power the bad boy and use rca's connected to my ipod to play tunes.. now the issue this time was when I put power to the "remote" input... the way i get power to the remote is just jumping from the power cable...i have never had a problem with doing this until this amp.. i touch the remote power to the input and the LED "power" light turns on showing the amp has power, not even a full second later bam bright ligth and small flames haha, my amp actually caught fire! so i quickly pulled the fuse out of the distro block and literally blew the little flame out haha..so im thinking that it can not handle that much juice from the remote turn on? im not sure, so i just wanted to get some opinions from you guys.. is this a bad way to test an amp? do you think this amp was about to blow anyways? just seems odd that a perfectly good , basically new looking amp would just blow up like that... and btw i didnt even have RCA's hooked up for the input OR speakers, so its not like i had music blasting or something as soon as i turned it on, it was just when i touched the power wire to the remote input....man so lame.. if i have time tomorrow morning i will take some pics of the amp guts and show the damage..its not too extensive.. just fried one of those black squares that is along each edge of the amp... not sure what they are or do...

what you think? my fault (this is my guess, but i dont know what i did wrong ) ? or faulty amp?

my first casualty in car audio


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## jtaudioacc (Apr 6, 2010)

faulty amp. it's also possible and probable, that the previous owner didn't have any problems with it.


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## TrickyRicky (Apr 5, 2009)

First of all the remote wire does not draw current. So it doesnt matter where the wire is coming from as long as it provides a constant 12v-14v which will then turn on the amplifier. Where did the fire come from?

Sometimes someone messes with the board or even a little loose wire strand could fall inside the amp (if this happends anything can happen). Thats why you always have to be careful when connecting amps without terminals on the end of wires (just loose wire strands screwed down to the terminals).

Your talking about the transistors mounted on the heatsink??


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## SQ_Bronco (Jul 31, 2005)

This is gonna sound awful, but are you sure you got the (+) and (-) right on the amp? And didn't screw anything else up?

Fun story, I once bought a ginormous amp used, (US-amps DE-3000) and accidentally hooked the 8GA speaker outputs to the +/- power along with the 8GA power/ground wires... (they were wired directly to board, and I didn't look very hard at what was what before hooking up/turning on). I mean, seriously, 8GA speaker outputs? With the same red/black wires as the power/ground? Coming out the same sidewall holes? Who does that?

(There were sidewall holes specifically for speaker wires, but these weren't being used. I should have realized, but didn't).

anyway, hilarity ensued, though less smoke than expected, due to the fact that I was well-fused. About a $600 mistake, although I think I've almost fixed it- for less $, but more hours of my time than I'd have liked.


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## zblee (May 18, 2010)

here are the guts










here is closeup of the burnt area











here is my layout for remote , + 12v and GRND...










you can see that the remote uses a wire clip or something , i didnt have one at the time, so i plugged in teh power and the ground.. yes they were up connected correctly.. double checked ( im sure they were ;D ) and when everything was good to go, i simply just touched the remote cable to the remote input and a second later, flame on ! haha


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## TrickyRicky (Apr 5, 2009)

the xistor beside it seems to be ready to go out too.


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## ChrisB (Jul 3, 2008)

Anyone remember the technical bulletin that Rockford Fosgate had out when the Punch 5002 was on the market? IIRC the bulletin warned against stripping wire anywhere near the amplifier due to the fairly open heat sink. As a result, one strand of wire getting in the amp could cause it to die, which is common with just about any electronic device.

As for the fire, I had a Punch 150 in high school that kept blowing fuses. The shop that installed the amp kept calling Fosgate and Fosgate kept saying "Install a bigger fuse." Well, the good news is that my amp didn't blow a 40 amp fuse but the bad news is that the circuit board went up in flames. As a result, Rockford Fosgate sent me a new amp.


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## zblee (May 18, 2010)

TrickyRicky said:


> the xistor beside it seems to be ready to go out too.


Are you refering to the other "little black box" that has some nearly black posts going to the board?



ChrisB said:


> Anyone remember the technical bulletin that Rockford Fosgate had out when the Punch 5002 was on the market? IIRC the bulletin warned against stripping wire anywhere near the amplifier due to the fairly open heat sink. As a result, one strand of wire getting in the amp could cause it to die, which is common with just about any electronic device.
> 
> As for the fire, I had a Punch 150 in high school that kept blowing fuses. The shop that installed the amp kept calling Fosgate and Fosgate kept saying "Install a bigger fuse." Well, the good news is that my amp didn't blow a 40 amp fuse but the bad news is that the circuit board went up in flames. As a result, Rockford Fosgate sent me a new amp.


Unfortunately I bought this on craigslist so I do not believe I have a chance at getting it replaced...


Is this a "fixable" amp, or just trash now? I may keep it just in case I find another working 500S that has a beat up chassis, as this amp is very clean on the outside...


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## ChrisB (Jul 3, 2008)

zblee said:


> Is this a "fixable" amp, or just trash now? I may keep it just in case I find another working 500S that has a beat up chassis, as this amp is very clean on the outside...


Just about anything can be repaired but it is a function of whether it is worth it or not. 

I just had a Power 351S listed for sale at $85, then I pulled it off the market. After PayPal fees and shipping, it was not worth my time to try to sell.


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## zblee (May 18, 2010)

ChrisB said:


> Just about anything can be repaired but it is a function of whether it is worth it or not.
> 
> I just


Well I guess I should rephrase my questions...

Is this a simple fix? swap out the broken part with a new one.. no real technical skills required except for soldering? I mean im looking at the board and I do not even know how i would remove the fried piece from the board safely haha... but i mean its dead now so I may just use this as a repair experiment and see what I can do with it


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## Pdogg (Jan 24, 2011)

It would normally be a simple fix but because of that MEHSA heat sink it will be a royal pain unless you're equipped to change those parts.
That appears to be a IRF3205 and if so fairly common/easy to find IF that's the only thing wrong with it.


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## zblee (May 18, 2010)

Pdogg said:


> It would normally be a simple fix but because of that MEHSA heat sink it will be a royal pain unless you're equipped to change those parts.
> That appears to be a IRF3205 and if so fairly common/easy to find IF that's the only thing wrong with it.



SO my quick googling of MEHSA heat sink led me to believe that the heatsink is basically the entire length of the board, those 2 small green strips on each side that all the "black boxes" are sitting on top of.. so in order for me to replace the one IRF3205 I would have to remove the entire heatsink , which involves UN-soldering ALL of the "block boxes" , replaceing the busted IRF3205 , and then resoldering all of them back in place? and maybe even having to replace the heat sink also?

bah that does sound like a pain, if that is what it entails... and if i guessed correctly.. sounds like i will not be doing this haha


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## TrickyRicky (Apr 5, 2009)

Yeah you would have to remove the circuit board (about 10-20 screws depending on model). Then unsolder the xistor's and drop in a few new ones (SAME VALUE, SAME PART). Beware that some parts are NPN or PNP just by an additional letter or different letter.

I just replaced all the electrolytic caps in my amp and now it works perfectly. As before a distorted signal and low wattage.

Just wondering, what is holding down those xistors? Usually there is sometype of bracket or bar bolted or screwed down holding pressure on the xistors that are on the heatsink. On yours a see none???


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## ChrisB (Jul 3, 2008)

I hate working with Rockford Fosgate MESHA strips. It is a royal pain in the ass to get the bad transistors off the MESHA without ruining something else and requires lots more patience than I have.

EDIT: When it comes to making that repair, you need to figure out why the transistors went up in a blaze of glory prior to replacing them. Otherwise your brand new parts may suffer the same fate.


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## [email protected] (Jun 12, 2008)

Most likely, something was wrong to make the transistor short out. There is chance that it was just bad, but there is a chance something else led to that. So if something else led to that and you just replace the transistor, then it could happen again. You would need to replace all of them on that side, not just the 1 so they all match.


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## zblee (May 18, 2010)

ChrisB said:


> EDIT: When it comes to making that repair, you need to figure out why the transistors went up in a blaze of glory prior to replacing them. Otherwise your brand new parts may suffer the same fate.


Exactly, I still do not know why it blew up, so I can see me fixing it, then as soon as i plug it in again, bam, same thing...

So back to my OP, why would the amp just burn up? could it be there was something on the amp ( like a piece of wire or something )... any other tests i can do other than just guessing?


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## TrickyRicky (Apr 5, 2009)

Yeah get the schematic for that amp or follow the traces to see what other components are before and after that xistor. Not all the xistors are the same, but they should be the same as the opposite side. You will notice how some are the same then it changes to a whole different xistor.

You can replace the two transistors that look bad, try it again, and if does the same then you will have to do some diagnosting.


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## sqshoestring (Jun 19, 2007)

I don't mess with those, they are soldered to the board and you need a heat gun. You can find on the net how to take them off. You can cut the legs on that, test the rest and cut any others that are shorted, then start the amp on a 10A fuse. That looks like the power supply, you need to figure out what ones are in the power supply they should be similar. It should run with only one on each side of the power supply if its a typical design. Why would it go bad, well, if the amp section is bad, piece of wire shorting it, maybe even bad cap or some thing shorting it. You should test that stuff before you replace. Other than that you can solder new mosfets in and if the resistors and drivers to them are good it should work. Yeah, the soldering is the easy part lol.


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## zblee (May 18, 2010)

well seems this may get more involved than i want to... I think i am going to just scrap it, or find someone that wants to buy it broke..I did not pay very much for it and it just is not worth it to me to put any time or money into it..

thanks everyone for the responses and tips, i was trying to determine if "I" would be able to fix it easily and with these responses I have gotten my answer.. "probably not" , so thank you guys for getting my question answered...


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## RBeachTL (Jul 21, 2008)

It looks like the orange wire connector contacted one of the leads of the transistor. Not sure what the orange wires are but my guess is a ground of some sort. Not sure why the connector got tweaked and contacted the transistor but it looks fixable if you can deal with the way the transistor is mounted.


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## TrickyRicky (Apr 5, 2009)

BINGO. The orange wire is just for ground. But why put it so dawm close to a xistor with no covers on the legs. Easy fix. 1 shrink wrap the terminal of the ground wire, replace the two transistors and should work.

Except I dont know how MEHSA works. Am use to the screw down clips or bars.


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## ChrisB (Jul 3, 2008)

The transistors are soldered to the MESHA strips which is why I absolutely HATE working with them.


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## alm001 (Feb 13, 2010)

YOaudioAINTnothinSON said:


> WHY do you fools know NOTHIN bout NOTHIN?! My amp catches on fire on a daily basis SON. You ask WHY??? because its the top HEAT playa. It be crankin out mad BEATS yo, so mad they make you go CRAZY.


Is there a way to subscribe to every post this person makes? I just canceled cable and I'm going to need some entertainment.


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## sqshoestring (Jun 19, 2007)

ChrisB said:


> The transistors are soldered to the MESHA strips which is why I absolutely HATE working with them.


LOL you said it. You can find how to do them on the net in electronics forums/etc. To be technical you could chop the legs and solder new transistors on just to test it and see if that fixed it, I think you can do that anyway. If you run a 10A fuse it should not overheat the transistors to run it idle, if nothing else is wrong with it. I used to do that and run them off a cheap DMM on the 10A, they should pull some current to load the caps then idle at 2A or something. If they keep pulling current something is wrong. Can also hold the transistors and touch power to amp to make sure they don't burn up. If they get hot quick you have trouble.

Where can I get some of those crazy beats....


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## zblee (May 18, 2010)

Well I decided to put ZERO time into this, so I just posted it up on ebay... if anyone is interested it is here 

Rockford Fosgate Punch 500S Car Amplifier Broken As-Is - eBay (item 230581541758 end time Feb-09-11 22:13:40 PST)

thanks again for everyones help/replies


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## TrickyRicky (Apr 5, 2009)

Am pretty sure it will sell for around 15-35 bucks. Goodluck.


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## sqshoestring (Jun 19, 2007)

There you got a couple bids already lol. It is a clean looking amp.


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## zblee (May 18, 2010)

sqshoestring said:


> There you got a couple bids already lol. It is a clean looking amp.


Ya I was stoked to see how nice of shape it was in when i first got it.. then of course i had to fry it haha.. oh well, someone will be happy once they get it fixed, nice amp for cheap


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## TrickyRicky (Apr 5, 2009)

Some want just the end caps as they go for around 10-20 bucks for a pair. Then add the heatsink which is pretty neat, someone is going to use that amp for a pull-a-parts amp.


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