p1000x2 no output

[punch45x2]

hey guys new to the forum and repair of amps but i am very familiar with soldering smd and through hole components. I have a p1000x2 that crapped out on me. Currently there is no out put on left or right channels and the yellow protect light is flashing. Any help on where to start would be great. Thanks again.

 

[Perry Babin]

Have you checked the output transistors to see if any are shorted?

Have you read the following page?
bcae1.com - Car Amplifier Repair Tutorial - The Basics

 

[punch45x2]

thats where i want to start but i am unsure what transistors are for the out puts. I am guessing it is q1 -16 left side and upper left of pic. do you need resistance on pin 1-2 and pin 2-3?

An externally hosted image should be here but it was not working when we last tested it.

 

[Perry Babin]

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[punch45x2]

thanks for the advice.

 

[Perry Babin]

They are on the left. Check all 16 from leg:

1-2
1-3
2-3

Do you read anything near 0 ohms on any of the outputs?

 

[punch45x2]

Irf3415 pin 1-2 pin1-3 pin2-3
Q1 26.3 24.2 2.9
Q2 26.5 24.2 2.9
Q5 26.4 24.2 2.8
Q6 6.5 4.1 3.0
Q9 26.8m 26.2m 8.3k
Q10 26.7m 26.2m 8 3k
Q13 26.7m 26.2m 8.3k
Q14 26.7m 26.1m 8.3k

 

[punch45x2]

Irf6218 pin 1-2 pin1-3 pin2-3
Q3 28m 27.5m 8.3k
Q4 28m 27.5m 8.3k
Q7 27.7m 27.5m 8.3k
Q8 27.7m 27.5m 8.3k
Q11 22.2 21.7 1
Q12 21.5 21.7 1
Q15 21.4 21.7 1
Q16 1.6 1.5 1

 

[Perry Babin]

1 each of the ones reading less than 10 ohms 2-3 are likely 'shorted'. It could be that the lowest reading one is the one that's shorted.

Pull them one at a time. When you find one that reads low out of the board, re-check on the board to confirm that the 2-3 readings of the rest are high.

For testing, you can operate the amp with only 1 on each rail missing to see if there are more problems. You can NOT replace only the defective parts. You must replace all 8 outputs in that channel (4-3415s, 4-6815s).

 

[punch45x2]

So I should start with q6 and q16 and recheck all others in board.

 

[Perry Babin]

Yes.

If those are the lowest again if you re-check them, I'd start with them.

 

[punch45x2]

So I took out q6 and q16 and the rest ohmed Into spec. I hooked up the amp with 2amp limit and it was powered up with no protect light and no dc voltage on speaker outputs. .03mv per channel. Once I checked that the power supply clicked off cause amperage trip. Then I checked the outputs and they are homing at like 26.5m. I checked the gate resistors but I could only check 6 or so,as the others went to a via. All source resistors are at .2 ohm.

 

[Perry Babin]

Without being clamped to the heatsink, the bias current may have drifted up as the output transistors heated up.

 

[punch45x2]

They were not. Took about 4 min. Should I check any thing else before I order parts. Do you now the location of the gate resistors. I only found like 5 or 6

 

[Perry Babin]

They should be very near the gate legs of the FETs.

The drive is the same for all 4 parallel outputs. Measure from gate pad to gate pad and make sure that you read the same between all 4 that are in parallel.

Have you tried to get the diagram from Rockford?

 

[punch45x2]

Am I reading resistance?and gate to what Ground.or is it continuity from gate to gate? I have not tried from rockford but it's a current model. The other gates run to a via. I will probably have to remove the board from heatsink?

 

[Perry Babin]

Yes. In parallel. Look at the attached diagram for an older model.

Yes, resistance.

 

[punch45x2]

Just to be clear I am checking resistance to gate to gate on the set of 4 in parallel?

 

[Perry Babin]

Yes.

 

[punch45x2]

Ok I will do that tomorrow morning. Thank you for being patient with me.