MTX Thunder Elite 1501d amp problems, could be fried?

[Infinity2600]

hey all, long time reader first time poster.
So heres the deal....
I have a MTX thunder elite 1501d amp hooked up to 2 15" kicker compvx's running at 1 ohm, everythings been fine for a while untill today, when there was alot of feed back when the volume was turned up, and almost sounded like the subs were blown. After a little troubleshooting i determined that the subs were fine, however my amp seemed to be the problem. When i opened it up i saw (picture below)....any idea how this happened, or even what this part is and if it would be possible to replace all of them? Any help would be great, i sure as hell dont want to spend another 800$ replacing this puppy.... thanks for any help

[Perry Babin]

HUF75339P

There are 5 more on the other side of the heatsink.

Sometimes they fail randomly. Sometimes it's due to shorted output transistors.

Check R112 and R111. Also check all of the resistors connected to the 1st leg of the 10 power supply FETs (5 of which are shown in the photo) after removing the blown FETs.

If you decide to repair this amp, NEVER power up the amp with the power supply FETs in the amp unless ALL FETs are tightly clamped to the heatsink.

[Infinity2600]

hey, thanks for the reply, what exactly are these FETS, sorry, im just unsure, and where could i purchase these parts, and how do i know which ones to get, all it says on these things is F1J29aa Z5339P, any more info would be awesome as i want to try and fix this amp. Thanks again

[Perry Babin]

Mouser Electronics - Electronic Component Distributor HUF75339P

[Infinity2600]

sweet man, thanks alot. so basically just order up 5 of those and swap them out and all should be fine? i really appreciate it dude

[Dr Zeus]

If there are 5 of these on the other side of the heat sync then they are quite possibly burned out as well unless this amp has two seperate power supplies. You can check them real quick with a digital volt meter. There should be no shorts between any of the legs of the three legged transistors.

Reason for failure could be anything, and it is quite possible that there are more faults inside of the amplifier. Undervolting, overdriven (1ohm), input voltage clipping, inadequate cooling (These MTX amps have inadequate heatsyncs with merely a fan to regulate). The top cover has a nice christmas tree though.

[Perry Babin]

You need to replace all 10 of the power supply FETs and check the resistors listed previously. You also must check the output transistors.

There's no guarantee that there won't be other problems. If there are other problems, it could result in the FETs failing again.

If you want to learn to do this type of work, we'll help you but it may not be easy or quick. If you simply want to get your amp working again, pay someone to repair it.

[Infinity2600]

Hey, so i got a DMM and checked the other side of the powersupply FETS and they all seem ok, i also went on to check the rest of them and everything checks out, as far as i can tell. can someone point me in the right direction on what else to check to make sure everything else is good? i would like to learn how to do this as it really interests me. I can post more pictures if needed. Thanks alot everyone.

[Perry Babin]

I suggest replacing all 10 power supply FETs even if 5 survived.

You can't check everything. You check for the most common faults and beyond that, you power it up to see if there are any more problems.

If you want to learn to do this type of work. Read the basic amp repair tutorial. If you read all of it and find yourself re-reading some parts to better understand them, you probably want to learn to do this type of work. If you get half way through it and find your mind drifting to other things and don't have enough interest to re-read any of it, you probably won't be able to do this type of work... well, not beyond the simplest of repairs. Either way, we'll help you get your amp working.

[Infinity2600]

why would you recommend replacing all of them? also, there are 5 on the other side the same size, but on both sides, there are more FETS that increase in size i checked them and they all seem fine. any ideas?