Testing FETs

[lowpsiTSi]

I recently purchased a Power Acoustik LT1920 amp for 20 dollars. I opened it up and found two FET's blown. I went ahead and replaced all FETs that were connected to the blown ones for a total of 6. I am by no means good at soldering on circuit boards but I have experience. The amp is still going into protect mode, I need to find a way to test each FET to ensure that there is a clean connection to each contact. Any help would be great.

[luka]

something probably went along with fets, have you checked fet drivers?

[Perry Babin]

Have you checked the output transistors?

[lowpsiTSi]

I will have to look I'm not very familiar with amp circuits. How would I check for shorts in the FETs?

[Perry Babin]

Check them as shown in the FET section of the following page:
Basic Amplifier Repair - Transistor Test Applet Link

[lowpsiTSi]

Ok I will check those later today. When I give the amp power, the LED will light up red indicating it is in protect mode. Then after two seconds, the LED will turn off. There was no change in behavior after I had replaced the FET's. Would this be an indication that the problem also lies elsewhere?

[Perry Babin]

Post the DC voltage on all of the terminals of the KIA494.

494
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16:

[lowpsiTSi]

494
Pin 1: 0
Pin 2: 5.09
Pin 3: 0.07
Pin 4: 0.20
Pin 5: 1.58
Pin 6: 3.55
Pin 7: 0
Pin 8: 0.60
Pin 9: 0.09
Pin 10: 0.09
Pin 11: 0.60
Pin 12: 11.09
Pin 13: 5.10
Pin 14: 5.10
Pin 15: 5.10
Pin 16: 0.97

[Perry Babin]

Are you sure that the fuses aren't blown?

[lowpsiTSi]

I got so caught up replacing the FETs that I completely forgot about the fuses. I put in four 25a fuses. I'm using a 12v computer power supply to test the amp, and now that I have installed the fuses, the amp led wont flash on, and the power supply kicks off immediately when I jump the terminals.

Should I get a 12v battery out and remeasure the DV voltage on the KIA494?