performance teknique amp icbm 9550

[ian33]

hi am workin on this performance teknique amp,this amp is in protect when i remove one of the main rectifer(+) amp powers up.i i check the outputs they seem ok i remove the driver board for the out puts but still no change there a two 12v regulators in the out put section that is getin a bit hot any ideas whould be good

thx

[Perry Babin]

It's normal for regulators to heat up.

Have you checked all of the outputs from legs 1-2, 1-3 and 2-3?

Is it possible that one transistor has a broken leg? Move the body of the transistor side to side while watching the point where the leg enters the body of the transistor. Sometimes they break just inside the body and you can't tell that they're broken by simply looking at it.

[ian33]

i check all the legs, all is good.now i put back the rectifer and i unsolder the output leg for the + 12 regulator now amp is out of protect + and - voltage on d out puts is ok but now i can hear a lil noise in the power supply can it be a bad op amp in the input section???

thx

[Perry Babin]

If not outputs have failed, it could have a defective driver board. The only way I know to check them (I'm not sure if it will work on this amp) is to remove all of the outputs and drive the input with a strong signal If the driver board is OK, you should see a 10v square wave (at the frequency of the audio signal) on the gates pads for the output transistors. This works best for amps that use complementary outputs instead of all N-channel outputs.

[ian33]

i do not have a scope yet. the amplifer is a mono block class x it has one driver board when i remove it the amp still stays in protect so i was guessing the driver board is ok???

[Perry Babin]

It's possible. Remove the outputs from the board and check for leakage from leg 1 to the other legs (for each individual transistor). With the meter on ohms, the meter should continue to read as it does if the probes are not in contact with anything.

[ian33]

output FQP12P20 AND FQP19N20

her are the readings i got with ther transistos out ot the board
pin 1 2 forward and reverse no reading
pin 1 3 forward and reverse no reading
pin 2 3 forward .506 reverse no reading

with all outputs out of the board amp power up i have 70.1 on pin 1 and 3 on the output pads with black probe on ground terminal

[Perry Babin]

Did you do this for all of the output transistors?

[ian33]

yes and my meter was on diode test on ohms the places that read .506 read 10.18m

[Perry Babin]

Confirm that none of the diodes on the driver board are shorted.