JX500/1D Protect mode

[joselorenzo]

Hi
I am looking for help with repair of Jx500.1d of jl audio.
The first problem that was detected is contact with water and two pieces of capacitor 63v 3300uf exploited. One of the capacitors was in total short circuit.
Replace the two 63v 3300uf capacitors.
Now just turn on the LED that indicates protection.

These are some measurements that I made
TL494 IC2
IC2
1-0.998
2- 3.56
3- 4.69
4- 4.01
5- 1.438
6- 3.54
7- 0.01
8- 4.94
9- 0.01
10- 0.01
11- 4.94
12- 13.54
13- 4.94
14- 4.94
15- 4.94
16- 7.19

IC3 MP18021
IC2
1- 13.63
2- 13.63
3- 0.01
4- 0.01
5- 0.01
6- 0.01
7- 0.01
8- 0.05

IC 1 LM358
IC2
1- 0.01
2- 3.38
3- 2.460
4- 0.01
5- 2.797
6- 0.332
7- 7.84
8- 9.01

 

[Perry Babin]

Are the FETs in the power supply?

 

[joselorenzo]

Are the FETs in the power supply?

The fets are connected to the board

 

[Perry Babin]

What's the DC voltage on all 3 legs of the PS FETs in each bank?

 

[joselorenzo]

Q8
1- .001
2- 13.65
3- .001
Q6
1- .002
2- 13.65
3- .001
Q5
1- .137 ** ?
2- 13.65
3- .001
Q7
1- .007
2- 13.65
3- .001

NOTE: In rail + caps 63v 3300 there are 13.03 volts

 

[Perry Babin]

Pull Q5 and check it for leakage from the gate to the other legs.

 

[joselorenzo]

I removed Q5. Outside the circuit and with tests it's fine.
Without Q5, the millivolts were measured.
D7 measure me low impedance.

D7 Is it a diode 1n4148?

 

[Perry Babin]

Probably.