Rockford fosgate power 1000 mosfet

[chipper]

Hey guys so I got in my first power 1000 I've never seen one in person. Now the problem is no audio from all four channels. This amp does turn on and if volume on source is all the way up it'll play some audio that is broken up or distorted at max volume on source. What should I check? I also checked all output mosfets none appear to be shorted.

 

[chipper]

Anyone?

 

[Perry Babin]

Is it producing both positive and negative rail and regulated voltages?

 

[chipper]

Yes there's 88 volts - + present.

 

[Hexhclass]

Yes there's 88 volts - + present.

And the regulated voltage?

 

[chipper]

How do you check for those?

 

[Perry Babin]

Black probe on RCA shield, red probe on pins 4/8 of the op-amps near the RCA jacks.

 

[chipper]

I have the following:

LM833N #1
1.105v
065.01mV
064.2mV
-16.83v

2.521v
1.213v
061.3mV
061.8

LM833N #2
-2.056v
-466.1mV
-466.3mV
-16.83v

2.523v
272.8mV
136.5mV
135.8mV

 

[chipper]

Those measurements were from those two op-amps I'll get the other two next

 

[Perry Babin]

check the 7818 voltage regulator.

 

[chipper]

How do I check that one?

 

[Perry Babin]

Post the DC voltage on all 3 legs of the 7818.

 

[chipper]

7818 with negative probe on tab:

Leg #1 07.10v
Leg #2 -000.1mV
Leg #3 5.737v

 

[Perry Babin]

The supply voltage feeding the regulator is too low. There may be another problem because the supply voltage on pin 8 was well below the 5.7v output of the regulator.

Check the diodes feeding pin 1 of the regulator.

 

[chipper]

Would that be those two?

 

[Perry Babin]

I would guess that two of the blue/white diodes with the striped end connected to pin 1 of the regulator.

What's the DC voltage on all terminals of the 7918? Black probe on tab of 7818.

 

[chipper]

7918:

Pin 1:-000.1mV
Pin 2:-47.28V
Pin 3:-18.10V

With negative probe on tab of 7818.

 

[Perry Babin]

That regulator is powered from the same supply as the 7818 so the problem is likely a corroded trace, bad solder connections or possibly defective rectifiers.

 

[chipper]

Are the measurements from the Lm833n similar to the other pair? I have not checked those yet. Approximately what does a good rectifier check out on diode check on the meter?

 

[chipper]

Does it matter if one of those capacitors are missing from the board the other is loose.