JL Audio 500/1

Perry Babin · 2011-09-13 3:33 am

I think this regulator should be rated for 1 amp of current. The 26 ohm load seems low (an older version reads 200 ohms) but I think it should be able to maintain voltage if it's not defective. Did you check the voltage on the output to see if it was 5v before you removed it?

mike49504 · 2011-09-13 3:52 am

Output is good.. I still have a problem though in the output section..

Amp powers on and starts drawing excessive current.. If i remove the rectifier amp powers up and idles perfectly..

I checked all drivers and replaced the outputs ..

Any ideas on where to check?

mike49504 · 2011-09-13 3:56 am

Ok i found that problem dont know how but the outputs shorted again..

Perry Babin · 2011-09-13 5:38 am

Did you check all of the resistors near the outputs. Sometimes they open which can cause the outputs to fail.

mike49504 · 2011-09-13 10:01 pm

Would 47.5 ohm 1% work for the power supply fets?

Perry Babin · 2011-09-13 10:12 pm

mike49504 · 2011-09-20 1:48 am

If i leave the outputs out of the amp and power it up R515 and R516 will burn up..

Is this normal since there are no outputs in the amp or do i have another problem?

Perry Babin · 2011-09-20 2:03 am

I'm not 100% sure but I think that they drive the gate of the FET and nothing else. Are you sure that there is no tiny solder bridge (top or bottom of the board)?

mike49504 · 2011-09-20 2:34 am

I cannot find any solder bridges on top or bottom of the board.

Perry Babin · 2011-09-20 2:44 am

Follow the traces. Do those components go to anything other than the gate of the low side FETs?

The 10 ohm and the diode are in series. Those are in parallel with the 47 ohm resistor.

mike49504 · 2011-09-20 2:49 am

One side of the 10 ohm and one side of the 47 ohm go to PIN 5 on a

TC4427E IC

Perry Babin · 2011-09-20 2:51 am

That's the driver IC. It drives the gates through the 3 components mentioned previously.

mike49504 · 2011-09-20 2:54 am

So is there a way to tell if its defective??

2 of the outs were shorted when i got it in for repair..

Perry Babin · 2011-09-20 2:58 am

From what I know about this amp, there should be no connection to anything except the FET gate so even if the IC was defective, it would not be able to pass current through the resistors. Did you follow the traces to see if those components connected to anything other than the gate and the driver IC?

mike49504 · 2011-09-20 3:13 am

They dont they just connect to the diode and the Driver IC

Perry Babin · 2011-09-20 3:19 am

There's no way for them to burn if they're not connected to anything.

Did you use your meter to check for continuity from the gate pad to the surrounding traces and lands?

mike49504 · 2011-09-21 2:53 am

I put the outputs back in the amp today..

When i power it up it burns 2 of the outputs up everytime..

I checked Q501 Q502 2N3906's they test fine..

Also checked Q502 that tests fine..

And i checked the diodes and 10 ohm and 47 ohm resistors they both test fine..

But the amp burns The outputs Q504 and Q505..

Any ideas?

Perry Babin · 2011-09-21 3:42 am

Did you determine why it was burning those resistors? That is a very serious problem if they're not connected to anything and they're burning.

mike49504 · 2011-09-23 1:15 am

I figured out the problem for thoose resistors burning..

Amp now just likes to burn Q504 and Q505 - outputs..

Any ideas??

I must have had a solder bridge on the pads cleaned them up and that doesnt burn the resistors so theres that problem fixed..

Perry Babin · 2011-09-23 1:17 am

Are the resistors and the diode all OK? You may have to remove one of the resistors to check the diode definitively.

JL Audio 500/1

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