burnt JL 500/1 v2 please help

[CarlosL]

Ive had this amp in the box for over 2 years, last week picked up a used 12" kicker L7 and box and wired everything up with a scoshe loc to the rear speakers on my car, 6awg pos to batt, 4awg ground with no remote cable because i planned on using the signal sensing feature. As soon as i powered up the amp it started smoking really bad
I shut everything off opened the amp and noticed 3 badly burnt IRZ44N transistors and one resistor. I checked resistance on the woofer and one coil is 4ohm the other is open the meter reads nothing.
Any suggestions on my issue? I plan on ordering all new Irz44N and a few resistors, do u guys recommend me replacing any other parts maybe the output transistors also.

thanks in advance
Carlos

[Perry Babin]

Have the output transistors failed?

[CarlosL]

Not sure perry, but when I checked them with my meter I was getting different readings from them.

Thanks for the reply

[CarlosL]

Here is the measurements of the four output resistors on the form from Perry's link to basic amplifier repair thanks again for your help.

[CarlosL]

sorry how about this

[Perry Babin]

Q506 and 507 appear to be shorted. There could be damage to the components that drove those transistors. You need to remove them and the IRFZ44s so that you can test the driver components. For the outputs, check the resistors.

To test the power supply, remove the Z44s and the rectifier and apply power. Measure the DC voltage on the gate resistors (the end not connected to the Z44s). They should all read approximately the same voltage (~5.5v DC).

[CarlosL]

Perry I removed all the IRFZ44s and the 2 in Q506 and Q507, are u saying to remove all the resistors to test them? One resistor in slot R605 I had already removed because it was burnt. Im assuming the rectifier is SF1606G in slot D600 is this correct? Should I remove the other 2 output transistors to test the power supply?

Thanks again Perry

[Perry Babin]

After removing the defective output and power supply transistors, you should be able to check most of the resistors.

Yes. D600 is the rectifier.

When you replace all of the power supply gate resistors (replace them even if they're within tolerance), install them a bit off of the board (see attached). This will help prevent damage to the board if the amp fails again.

[CarlosL]

Perry I checked the voltage at the resistors all read between 4.94v-4.97v (at the end not connected to the irfz44ns) and 4.92 on the other end connected to the irfz44n. Does this mean that everything else on the amp should be fine or are there any other components I should test? I used a small jet ski battery as my power source I hope is sufficient for testing. Another question i got is the rectifier i removed is this likely no good either or is there a proper way of testing it.
Thank you

[Perry Babin]

As long as the rectifier doesn't read anything near 0 ohms between any of the legs, it's likely OK.

You also need to check the resistors near the outputs. Also use a high-power lighted magnifying glass to see if any have visible damage to the tops of the resistors.