Im newb here need help repairing 2- punch 250a2's

Whosnxt

Member
2016-02-28 1:00 am
Let me introduce my self im a newby this my first post. I have very limited tools and basically just have a multimeter and soldering iron and very basic knowledge of amps but i love fixing things and i have a love for old school usa fosgate amps. Im wondering if i could get a schematic for a 250a2 board # is 2035-H. I know i have shorted power supply fets on both amps and way out of tolerance gate res to same side on both amps. I have stupid ? Do i have to pull out all the output irf9540's and irf540's to check or can i leave them in? Thanks for any help. And ive been reading some threads and Perry your a genius. Thanks Travis. Sorry for long post
 

Whosnxt

Member
2016-02-28 1:00 am
I hope i can fix it. output transistors are reading complete short across all legs no matter how u check it circuit. Also let me add this amp had been prev worked both mtp75n05's were raised and not soldered down to strip. When i applied power and rem it instantly popped ps fet q6. Then i checked there was a short across + and - input on amp i clipped that fet out now 98ohms across + and -.
 
With most Rockford amps, you can check the drive circuit for the FETs by connecting only remote and ground (no B+). If you do this with the PS FETs in the circuit, you can tell if there is damage to the drive circuit.

You likely have defective driver transistors or out of tolerance gate resistors.

If all of the outputs are reading 0 ohms across all legs, you'll need to remove them before you try to power up the amp again.
 

Whosnxt

Member
2016-02-28 1:00 am
thank you and yes the gate res are bad on one side supposed to be 68ohms and are up in the K range. this will be a slow repair as I don't have any parts here. I have ordered ps supply fets pt# Irf 3205 and surface mount res. 47 0hm from china as seen from other threads you were helping out in. I have bare minimum tools I don't even have a power supply except car wiring. I'm gonna start looking for a power supply. I also ordered output fets also as figure there prob bad. Gotta wait for that stuff to come in I guess. Thanks for your help Perry your the best if you think of something else I can check in the mean time let me know thanks!
 

Whosnxt

Member
2016-02-28 1:00 am
With most Rockford amps, you can check the drive circuit for the FETs by connecting only remote and ground (no B+). If you do this with the PS FETs in the circuit, you can tell if there is damage to the drive circuit.

You likely have defective driver transistors or out of tolerance gate resistors.

If all of the outputs are reading 0 ohms across all legs, you'll need to remove them before you try to power up the amp again.

are the driver transistors the same as PS transistors sorry for my ignorants.
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi Whosnxt,
It's not even worth trying the parts from China. Get them from a real distributor like Mouser or Digikey. There are other good suppliers also. Most will have parts in your hand in a day or two just to really give them a push.

What was the Ebay store / seller you got them from?

Back to Perry ...

-Chris