Sparks from amp

[chewy04]

I recently installed a Hifonics Bx1000d amplifier. About 5 seconds after the amp turned on there were sparks comng from it. The fuse at the battery blew but not the one on the amp. I opened up the amp to see what was broke and it appears that 3 of the MOSFETs are fried. Does anyone know what would cause this to happen and why the amp fuse did not blow?

 

[djQUAN]

did you get your amp brand new or second hand?

 

[chewy04]

I got it second hand.

 

[richie00boy]

Maybe somebody replaced the amp fuse with too high a value, or the battery fuse is lower than the amp fuse value..

As for the fault, it's difficult to say. Best thing is to look where on the board may have got burned. Could be power supply or output stage.

 

[chewy04]

I know that 3 of the MOSFETs are burned...that appears to be the only damage. I have replacements parts coming. Im hoping that replacing those will fix it.

 

[raidfibre]

I know that 3 of the MOSFETs are burned...that appears to be the only damage. I have replacements parts coming. Im hoping that replacing those will fix it.

I don't mean to discourage but there's probably a real reason why they blew up, but maybe not.
Did the amp appear to have gotten wet ever?
Good luck, let us know how it goes.

 

[djQUAN]

to save you probably lots of money, before installing the new switching mosfets (assuming the mosfets are used in the primary side of the SMPS) run the amp without them, then check the oscillator with an oscilloscope to see if it is still in good condition.

 

[chewy04]

Thanks for the help guys. I will post an update after I replace the MOSFETs.

 

[chewy04]

Well, I replaced the MOSFETs and reinstalled the amp and it happened again...3 seconds of power and then the MOSFETs blew. I know my wiring is correct because I have a different amp installed and it is working fine. I do not think there is much more I can do myself so I will probably have to send it out to be repaired.

 

[li_gangyi]

it was probably the controller that forced the mosfets to remian on...thus creating a huge current flow and blowing it up...you should've checked the driver portion BEFORE deciding a replacement was necessary...

 

[micutu]

give some detailes maibe some pictures, how many mosfets were in the smps? you can reach me ay athenee@xnet.ro

 

[xplod1236]

it was probably the controller that forced the mosfets to remian on...

That's assuming that the those were the ps fets.


chewy04, which fets blew, ps or output?

 

[chewy04]

I'm very new to this so I don't know which ones they were. I will try to post some pictures of them later.

 

[chewy04]

here is a pic of the amp...the blown fets are in the bottom right.

 

[xplod1236]

could you post a picture of the whole pcb

 

[chewy04]

Here it is.

 

[djQUAN]

I think those are the PS fets.

 

[SkinnyBoy]

is that it? lol this is what I was faced with.....

can't you still read the numbers on yours? (I didn't bother reading the rest of this thread )

 

[bkoopman]

Yeah, those are the transistors in your power supply. If you still need help with this, do post and I'll see what I can do. I assume that everything obvious (ie, loose clamps) can be ruled out? And that you replaced them with the exact part? Did you only replace 3, or the whole bank? It probably won't be a simple fix, but I can at least help you diagnose the problem. Do you have any sort of equipment, at least a multimeter?

 

[chewy04]

Thanks again for the help. I only replaced the three that were blown. I used the exact part. I visually inspected the whole pcb and did not see any other damage or loose parts. I do not have a multimeter but I can get one. I dont have a lot of experience with this but I am a fast learner and would greatly appreciate any help you could give.