JL Audio 1000/1v2

[Perry Babin]

Pin 2 is the input, 6/7 are the outputs.

Pin 1 should be 12v.

 

[caraudioguy2100]

That’s what I meant pin 2 square wave and on pin 6,7 of both ic’s

 

[Perry Babin]

Do you have a good square wave on the gates of all of the outputs?

 

[caraudioguy2100]

On Q500,501 I get 10 volts on the gate pad is this normal ?

 

[Perry Babin]

Those are driven by the 4420 Check the gate resistors.

 

[caraudioguy2100]

I think something is wrong with 1 of the boards that sits in front of the outputs .

When it’s install I bet 98 volts on all 3 legs of the outputs Q500,501,ect when removed the voltage is normal

 

[Perry Babin]

The vertical boards drive the high-side FETs. The FETs you listed are the low-side FETs and are driven by the 4420s on the main board.

 

[caraudioguy2100]

I still have an isssue I have full rail voltage measured directly across the outputs

not sure where the voltage is coming from

 

[caraudioguy2100]

I’m gonna order some new parts for this again since I had it powered up and it blew the outputs

 

[Perry Babin]

Remove all outputs and troubleshoot without them.

 

[caraudioguy2100]

I removed the outputs and the dc voltage is gone across the speaker terminals .

I know the outputs weren’t the issue causing the dc across the speaker terminals .

So where do I go from here

 

[Perry Babin]

Solder a bridge between pins 6 and 7 on U517. That should give you an approximate 50% duty cycle drive on all gate pads for the output transistors.

 

[caraudioguy2100]

Here is what I get on the following
Q500,501,506,507

The last pic is what I get on Q502,503,504,505

 

[Perry Babin]

The high-side is floating. There should be no voltage on the source leg of the high-side FETs. Confirm and then (if there is o voltage) ground the scope probe to the FET source leg and re-check. This is best done in differential mode but using the ground clip will work if there is no voltage.

 

[caraudioguy2100]

Q502: 126.1
Q503: 126.1
Q504: 71.7
Q505: 71.7

This is what I get on the source leg for the outputs (3rd leg)

 

[Perry Babin]

Touch an incandescent lamp (one terminal connected to ground) to the high-side source pad. Does it light up?

 

[caraudioguy2100]

No but I tried with a light bulb for a house .

I will get a 12 volt light bulb and try again

 

[Perry Babin]

That means there there is no voltage source connected to that pad. If you can't use your scope in differential mode, ground the source pad through the lamp and re-check the gate signal.

 

[caraudioguy2100]

I grounded the scope probe to the source leg and here is what I get on Q502,503,504,505

 

[Perry Babin]

I don't see anything that could be causing a problem.

Try all again with a 0.01uF loading capacitor. You can ground the scope to the source pad for the low-side FET pads to get a cleaner signal.