ppi pcx 1250 problem

[3nCod3R]

The amp stays in standby all the time drawing almost an amp. Any ideas ?

[Perry Babin]

Have you checked the output transistors?

[3nCod3R]

I have not checked anything on the board yet, just a visual inspection that has revealed a hot resistor (R34) which feeds one of the transistors. It reads 80 ohms, the others in the same bank read 18 ohms. The next question is how to remove the board from the case, it seems they must have a jig to assemble/disassemble this unit. All the transistors are clipped in to a rail on both sides of the board.

[Perry Babin]

Read THIS.

You can probably check the outputs without removing the clamps.

What transistor (part number on face of transistor) is that resistor connected to?

[3nCod3R]

Got the clamp off, works well when you know the trick, thanks. The part number on the transistor is RFP70N06, and it is cracked wide open.

[Perry Babin]

You'll need to replace all of the RFP70N06s. You still need to check the output transistors.

[3nCod3R]

Just an update for anyone who has this type of problem in the future.....replaced all of the mosfets for the power supply and the unit functions normally. There were several that were shorted, and since they are in parallel, it was causing voltage to drop on the gate resistors. Thanks for the help !