JL Audio 500/1 repair info

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hello,
I have here a JL Audio 500/1 d class monoblock. Power supply failed, I changed all mosfets (FPQ65N06) and gate-resistors (47 ohm).
Worked, but has very low railvoltage, maximum undistorted output is 15w, then it clips.
I think the drivers of the mosfets from the PS are also faulty, I measure a pulses of about 5v and 1,7uS from the SG3525 (OK) but after the drivers they are distorted.

Drivers are UY 142 and WY 143
I looked at smd coding tabels etc. but can't find them....which type I can use here??

Thanks,
Rob.
 
OK thanks. I measure 150v DC with the rectifier disconnected from the rest of the PS. Just AC input, no load.
So I think something's wrong with the feedback of the regulation. Also a resistor was burnt 6k2 (R661) which I changed for 6k8, difficult to see what this resistor do without schematic. Could be in the PS regulation loop, not sure.
Rob.
 
Last edited:
What is the voltage on the first two pins of the driver board (looking at the component side of the driver board)?

I think you'll have to have the rectifier installed but I'm not sure.

Are you 100% sure that you read 160v DC on the center leg of the rectifier? It should have caused the filter caps to vent at 2x their rated voltage.
 
I connected only the outside legs of the rectifier to the board. The center leg is not connected, floating. Then I measure 150V dc. No regulation offcourse.

With the rectifier connected (normal regulation) the output is about 40Vdc.
Or the PS regulation is defect, or the amplifier is..

But with signal on, I have normal amplifier output to 15w, then it's clipping.

So I suspect the regulation of the powersupply.

Strange problem...
Rob.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.