Rockford Fosgate Power 1501 BD

[Hexhclass]

This amp does not power on.I think it powers up and then go to protect.
Rail caps have massive charge.

pwm IC

1:4.97
2:3.689
3:4.22
4:4.70
5:4.79
6:0.001
7:0.001
8:4.28
9:3.724
10:2.016
11:0.003
12:4.63
13:6.50
14:15.34
15:0.001
16:6.25
17:15.37
18:4.97

 

[Perry Babin]

If the protect LED remains lit continuously after remote is applied, post the DC voltage on U21. They commonly fail.

 

[Hexhclass]

LED goes off

 

[Perry Babin]

Post the voltage on all pins of the LM339.

 

[Hexhclass]

339 IC

1:4.37
2:4.37
3:14.99
4:0.267
5:1.653
6:3.799
7:4.96
8:2.82 and goes down slow to 0.176
9:3.203
10:4.96
11:7.81
12:0.001
13:4.16
14:0.001

 

[Perry Babin]

Do you have a square wave with an amplitude of about 25v on the tab (center leg) of all of the power supply FETs (to confirm that both supplies are functioning)?

Do you have a carrier wave (square wave) that swings about 80v on the output FETs?

 

[Hexhclass]

All PS FETs have same wave form on center leg.

Outputs group one (in a pic here i see they mark as switchers ) 3415/6215 10v/dv 10/us

 

[Hexhclass]

Outputs group 2 10v/dv 10/us

 

[Perry Babin]

Do you have audio at pin 1 of U4?

 

[Hexhclass]

I see audio on pin 4


I don't know what happen but the amp now has output.There was no supply voltage on the op amps when it came in.I have done no work on it just test.maybe something is failing?

 

[Hexhclass]

U21 cause problem like this before it fails?

 

[Perry Babin]

If U21 is the problem, the protect LED never goes off.