JL Audio 1000/1

[caraudioguy2100]

When trying to power up the amp it draws excessive current .

I checked all outputs and power supply fets they all test fine .


Only thing I noticed is on the power supply fets between gate and source legs I get 47 ohms I think that’s normal for this amp .

Any ideas since I can’t seems to find anything shorted

 

[Perry Babin]

Does the current draw start IMMEDIATELY after remote is applied or does it take 2-3 seconds for the excessive current draw?

Yes. You should read the gate resistor value.

 

[caraudioguy2100]

I will have to get back to you on that .

Testing a large amp and my power supply broke again .

Blew the transistors that I just replaced

 

[Perry Babin]

Did you replace all of them?

Did you confirm that all of the series resistors were within tolerance?

 

[caraudioguy2100]

I replaced them all . And I checked the source resistors . I replaced them again and now my supply is up and running .


Back to the amp .

It takes 2 to 3 secs when applying the remote for the amp to draw current

 

[Perry Babin]

Confirm that the FET that's driving the low-voltage transformer has oscillation on it's tab before the current draw begins.

 

[caraudioguy2100]

Yes I get oscillation before the amp draws current

 

[Perry Babin]

That would seem to indicate that the problem is in the rail supply.

Check the rectifier
The 4 diodes near the 5w resistor R871
Twist the transformer to see if that makes a difference.

 

[caraudioguy2100]

The diodes check fine . Tried pulling /twisting the transformer no change .

I pulled the rectifiers and the current draw stopped .

I checked the rectifiers in diode check but they test fine

 

[Perry Babin]

Shorted secondary PS inductor?

Possible output driver board faults?

Did you check the output FETs carefully?