fried ny Rockford Punch 40.2

[chipper]

This really sucks i got into my car and and as soon as i turned on the car it smoked! Everything hooked up right i don't get it what went wrong????? And it was thumping just fine the same day it died. From what i can see power supply fets cooked i was surprised that there was no big damage to the circuit board just a bunch of resedue from all the smoke and now my car stinks. Now my question is where can i get the power supply FETs from? Or kind of sub would be good? This is really a pain still trying to repair a 150a2 now this.

Any help would be appreciated. Thanks

[Perry Babin]

Digi-Key - IRFZ44PBF-ND (Manufacturer - IRFZ44PBF)

You also need to check the gate resistors, the driver transistors (near the TL494) and the output transistors.

[chipper]

Originally Posted by Perry Babin

Digi-Key - IRFZ44PBF-ND (Manufacturer - IRFZ44PBF)

You also need to check the gate resistors, the driver transistors (near the TL494) and the output transistors.

You mean the IRF540 & IRF9540?
how about CR2 & CR1?
The Gate Resistors by D3 & D2?
Also do i need to remove the driver transistors to test or can i test with them installed?

Much thanks Perry for your help.

[chipper]

Originally Posted by Perry Babin

Digi-Key - IRFZ44PBF-ND (Manufacturer - IRFZ44PBF)

You also need to check the gate resistors, the driver transistors (near the TL494) and the output transistors.

If these are the gate resistors i checked them and i got:

98.8 near D3
98.9 near D2

Is this normal?

[Perry Babin]

The 540s and 9540s are the output transistors.

CR1 and CR2 are rectifiers and rarely fail.

Those are normal if the gate resistors are marked 101.

After removing the power supply FETs, measure the DC voltage on the 3 points indicated by the arrows in the second photo (assuming that yours is roughly similar). The voltage on those points should be ~5-6v DC. Also measure the voltage on the solder pad for the first leg of each of the power supply FETs. The voltage there should be the same as on the points indicated by the green and orange arrows.

[chipper]

Originally Posted by Perry Babin

The 540s and 9540s are the output transistors.

CR1 and CR2 are rectifiers and rarely fail.

Those are normal if the gate resistors are marked 101.

After removing the power supply FETs, measure the DC voltage on the 3 points indicated by the arrows in the second photo (assuming that yours is roughly similar). The voltage on those points should be ~5-6v DC. Also measure the voltage on the solder pad for the first leg of each of the power supply FETs. The voltage there should be the same as on the points indicated by the green and orange arrows.

This is what i got for the following:

Q2 = 0.638
Q1 = 0.636
Q5 = 0.635
Q4 = 0.637

Now i had the VOM on diode check.
Also do i do the other testing with power to the amp? i already removed the ps FETs. Thanks for the help.

[Perry Babin]

Set the meter to DC volts and power up the amp normally. Then measure the voltage on the points indicated by those arrows and on the gate pads. Place the black meter probe on chassis ground. Place the red meter probe on the point where you need to measure the voltage.

Yellow arrow DC volts:
Green arrow DC volts:
Orange arrow DC volts:
Gate pad FET 1:
Gate pad FET 2:

[chipper]

Originally Posted by Perry Babin

Set the meter to DC volts and power up the amp normally. Then measure the voltage on the points indicated by those arrows and on the gate pads. Place the black meter probe on chassis ground. Place the red meter probe on the point where you need to measure the voltage.

Yellow arrow DC volts:
Green arrow DC volts:
Orange arrow DC volts:
Gate pad FET 1:
Gate pad FET 2:

When powering up the amp w/o ps FETs do i hook the REM wire also?

[chipper]

Originally Posted by Perry Babin

Set the meter to DC volts and power up the amp normally. Then measure the voltage on the points indicated by those arrows and on the gate pads. Place the black meter probe on chassis ground. Place the red meter probe on the point where you need to measure the voltage.

Yellow arrow DC volts:
Green arrow DC volts:
Orange arrow DC volts:
Gate pad FET 1:
Gate pad FET 2:

Do i put the negative probe on the heatsink chassis???? Thanks

[Perry Babin]

Yes.