Rockford 360.6 - blown power supply MOSFETs

[pac1085]

Hi, I have a rockford 360.6 with blown power supply MOSFETS. The amp blew when I was re-routing some wires in the front of the car a few years ago. Possibly related to the pre-amp inputs or +12v remote turn on wire?

I have some basic electronics knowledge, and tried replacing all of them (Motororla MTP50N06V) and as soon as I applied power the new ones burnt up.

Does anyone have a schematic for this amp, or any guidelines on where to look?

Thanks!

 

[Perry Babin]

If you haven't done so, read the entire basic amp repair page (link in sig line below). That will help you with the basics.

 

[seankane]

Did you make sure the gate resistors for the power supply fets were within tolerance and had a good connection?

Did you replace the pnp and npn driver transistors for the power supply fets?

Also did you confirm there were no solder bridges between the legs of the power supply fets?

Post a pic of the board where you did the repair.

I think I have the schematic somewhere I will look.

 

[pac1085]

Hi guys...

Thanks for the insight. After posting this thread, I noticed a burnt trace on the board near the power supply PWM controller chip.

Here are some pics:

Are there any equivlent replacements for the MTP50n06v that I can use?

 

[seankane]

You can still purchase those MTP50N06V's brand new.

I would use IRF3205 and change the gate resistors to 47 ohm.

Also you need to change the drivers to after a second failure they are sure to be shorted.


Looks like in the pic they would be marked 1GM and 2GM which are MMBTA56 and MMBTA06. The transistors in location Q4, Q5, Q6, Q7.

 

[seankane]

E-mail me at seankane89@hotmail.com if you want the schematic.

 

[pac1085]

Thanks for the info. Do you have any ideas why the trace near the PWM controller could have blown? Do you think it could have been related to static in the remote turn on line?

 

[pac1085]

Well, 4 years later (and about 9 years after I blew up the amp), I managed to repair it thanks to the advice in this thread.

1. Repaired burnt up PCB trace
2. Replaced all 4 drivers
3. Changed gate resistors to 47 ohm
4. Replaced MTP50n06v's with the IRF3205 (qty 8)

Amp fired right up and is working great. Still no clue what caused the failure in the first place.