Testing 250A2 no power up

[bagged2drag]

testing 250A2 no power up

Measure the resistance points A-B and D-E (amp not connected to any source of power). If you get something greater than ~1meg ohms, power the amp up through a 5 amp fuse (nothing larger). Measure the DC voltage at all points in the photo and post the results. The black laed will remain on the ground terminal of the amp for all measurements. Also post the voltage on the remote and B+ inputs (again, black lead on the ground terminal).

Hello,

I know this is an OLD post, but...
I am trying to repair the same type of amp. Per your suggestion, I have tested the fets. I have the following voltages:

A: 0.00
B: -0.08
C: 0.00
D: 14.87
E: 14.87
F: 0.00

Any help is appreciated.

Kris

 

[Perry Babin]

Points B and E should have approximately 12v. Point B with essentially no voltage seems to indicate that you have some board damage. Point D having the same voltage as point E means that the FET has failed.

At the very least, both FETs in the power supply will need to be replaced. Expect to have to replace both gate resistors and the driver transistors as well.

You'll need to check the output transistors as well. They may have failed causing the power supply to fail.

You may want to read through the following thread.
http://www.diyaudio.com/forums/car-audio/293482-rockford-301s-wont-power-up.html