Feasible to fix a blown amp? I think its just the mofsets.

[ExtremeODD 10+ year member]

Well I have a phoenix gold xenon 600.1 that I managed to short out somehow. Ive had it for 6-7 years and in 3 different cars. Ive hooked it up and unhooked it a million times, this time I think I had a few strands of + touching off on the metal case which is also connected to the large metal heatsink that everything seems to be grounded on. I heard 5 distinct pops as I was getting shocked while pulling the + out (shocked from the case). Ive popped it open and found 5 obviously blown mofsets. They look easy enough to replace but should I just do the blown ones or all of em just in case? They are a fqp50n06 mofset, found some for cheap here. FAIRCHILD FQP50N06L is in stock | Buy FQP50N06L | Onlinecomponents.com Should be the correct one but who knows with electronics. Ill get some pics up in a bit.

I figure I cant make it any worse, its pretty fubar'd as is.

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[akheathen Premium Member]

thought you were gonna shoot me some pics of it....... been waiting, lol. really, you do not want to go cheap, not to say you cannot get them at a good deal. you will need to replace all of them, and order at least 10 to make sure they are matched. make sure they are at least a good brand. the resistors need to be replaced, as well, and check the driver. check the outputs for shorting across the legs, too. did you ever figure out where exactly the shorting occured? i would still be interested in the amp to match to mine, so please be carefull not to damage the traces and pads. it helps to cut the legs off the transistor and remove one at a time, and be sure to ****, or blow the holes out before installing the new ones.

 

[ExtremeODD 10+ year member]

Alright sorry for the delay on pics, some friends came by and I got drunk. **** happens, anyway here are the pics. Sorry bout the quality its an og droid.

















Not sure if that one is blown or just a messy connection.

 

[ExtremeODD 10+ year member]

Alright, so I decided to remove the heat sinks. It was easy enough since there was no thermal paste on top, only between the mofsets and the base plate which isnt sticky strangely enough. The 5 pops I heard were 4-5 of em literally exploding and 1-2 just cracking. Im either going to try replacing all of em or just sell it as is, but its a good project anyway. Great soldering practice, Ive built a few things including 2 lasers from scratch (pulling diodes from sleds, building my own driver) so I can handle a soldering iron quite well.

I wonder if I can get a multiple tip iron, like a tiny trident rofl.









Pretty sure those are fine.











Notice the bigger one has no burns, thats why I think those big guys are probably fine.

Seems fairly straight forward, I could break the job into chunks like take off half or all of the mofsets then later or the next day put all the new ones back one. Im not worried about the quality since its the same manufacturer unless Fairchild has declined in quality since 2003 when the amp was made. Its also quite affordable to simply replace every mofset, even all the ones that were untouched due to the amp not even really powering on just to avoid later frustrations. Looking closer Im pretty sure I can just lay the tip of my soldering iron across all 3 spots at once to quickly pop em out without putting too much heat on em.

 

[akheathen Premium Member]

those big ones (to227 case) are the rectifier diodes. pull them and test them individually, and do not install them untill you have the power supply working and stable. look for shorting across any and all legs of the output transistors. i would hate to see them go poof again in the power supply if it was somehow through the output section that it looped. all those resistors need replaced, i always step up to the next watt range. follow the traces and check the power supply driver(s) for shorting, too. many times the fets will take the drivers with them, but not always. also, if they are messed up, they can cook the fets without any load on them. make sure that heat transfer pad is not leaking any voltage. do not power it up without the fets clamped, and the pink pad, or little plastic pad, and paste under it..

 

[ExtremeODD 10+ year member]

Or on that note I may look to unload it, may be a bit over my head.

 

[akheathen Premium Member]

lol, lmk