Fixed/Fried My Amp!!!

[Death By Bass 10+ year member]

There is in fact a bulging capacitor near the speaker outputs. It's not leaking anything but it appears to be open. This could be the problem ey?

yes, it could be the problem

replace it, and see what happens.

 

[soulstace 10+ year member]

Will do tomorrow. Thanks!

BTW any tips on discharging the capacitor before replacing it? This one is a 47uF(K)100v I don't have a clue if this is dangerous or not.

 

[Death By Bass 10+ year member]

Will do tomorrow. Thanks!
BTW any tips on discharging the capacitor before replacing it?

yeah... just one tip... it doesn't need discharging

 

[snoopdan 5,000+ posts]

Those caps are such low capacitance that it wont hurt a fly.

as far as the first guy's amp is concerned, I highly doubt the reason it shorted was because of some goop, its non conductive anyways. let me ask some things about your amp first though, did it fry the first second you put the power leads to the amp, or when you tried to turn it on via remote switching from your remote turn on lead power? Plus a pic of the damage would do me well in trying to figure out where the damage stemmed from and what needs to be looked at. Usually amps fry when people run the amp at an impedience lower than the fet's can handle thermally, and they bust/crack and or catch on fire. Also you must try to get an exact part replacement from the correct semiconductor manufacturer, since even though one company makes IRF9640 for example, its an International Recitifer part, but Fairchild makes their bastard version of it, as well as Phillips and Intersil. All three claim a Vd of 200v, Rp of .15 Ohm and Id=18a but have different attributes like single pulse avalanche energy, and pulsed drain current. These little differences are enough to screw up the left and right biasing of the amplification stage....some amps rely on the natural switching function of the chips to regulate this, others have a variable resistor biasing circuit to make sure the sine wave doesnt go too goofy into distrotion / overlap. For bias circuit adjustment, you really need to contact the tech support of the company who made the amp and pray to god you find somone on staff with half a frontal lobe.

 

[jrouter76 10+ year member]

Those caps are such low capacitance that it wont hurt a fly.
as far as the first guy's amp is concerned, I highly doubt the reason it shorted was because of some goop, its non conductive anyways. let me ask some things about your amp first though, did it fry the first second you put the power leads to the amp, or when you tried to turn it on via remote switching from your remote turn on lead power? Plus a pic of the damage would do me well in trying to figure out where the damage stemmed from and what needs to be looked at. Usually amps fry when people run the amp at an impedience lower than the fet's can handle thermally, and they bust/crack and or catch on fire. Also you must try to get an exact part replacement from the correct semiconductor manufacturer, since even though one company makes IRF9640 for example, its an International Recitifer part, but Fairchild makes their bastard version of it, as well as Phillips and Intersil. All three claim a Vd of 200v, Rp of .15 Ohm and Id=18a but have different attributes like single pulse avalanche energy, and pulsed drain current. These little differences are enough to screw up the left and right biasing of the amplification stage....some amps rely on the natural switching function of the chips to regulate this, others have a variable resistor biasing circuit to make sure the sine wave doesnt go too goofy into distrotion / overlap. For bias circuit adjustment, you really need to contact the tech support of the company who made the amp and pray to god you find somone on staff with half a frontal lobe.

I got a question for you Snoopdan I open up my DEI2400d which I bought oof ebay and notice that the transitors at the power connection end seem to have gotten hot becuase there is some brown like substance around them on the board and it has a smell none of the resistors are burned but seem to have a film on them brown...you don`t think it is burnt out there do you.

 

[helotaxi 5,000+ posts]

jrouter-the amp has been repaired. The transistors blew at some point and were replaced. Whoever did the repair didn't bother to clean up the mess from the problem and just replaced the destroyed components.

Too the original poster-firstly, gasket sealant is not a replacement for thermal compound. It is doubtful that the sealant had anything to do with the second problem. It is possible that there was a bit of stray solder or a lead that you left too long on the solder side of the board. Also, as mentioned above, if you didn't isolate the FETs from the heatsink it would have shorted that way. A short of that nature would surely toast the FETs in question.

 

[620hpcrx 10+ year member]

The original mica film was left in place so that isn't the problem. The FETs fried right when I put the main fuse from the battery back on. BTW there was a large amount of current draw when this was done...not enough to blow the 80amp fuse though...just a pretty loud pop. I also made sure my solder joints were clean...no stray globs anywhere...but the leads were a little long but not to the point where they would ground to the heatsink.

 

[jrouter76 10+ year member]

jrouter-the amp has been repaired. The transistors blew at some point and were replaced. Whoever did the repair didn't bother to clean up the mess from the problem and just replaced the destroyed components.
Too the original poster-firstly, gasket sealant is not a replacement for thermal compound. It is doubtful that the sealant had anything to do with the second problem. It is possible that there was a bit of stray solder or a lead that you left too long on the solder side of the board. Also, as mentioned above, if you didn't isolate the FETs from the heatsink it would have shorted that way. A short of that nature would surely toast the FETs in question.

Hey thanks much love to you for the info