jbl gtq 190

[mike49504]

Im wonrking on this amp and it has me puzzled.

For the rectifiers it has a sf163a and a fep16bt in the board looks like the fep16bt is not orignal .

Wondering is the fep16bt = to a u1620?

And second thing is its sending the rail voltage to the speaker outputs

wondering if you can help me on this amp Any help would gretly be appericated

[Perry Babin]

Those rectifiers should work. An MUR1620 can replace the fep16bt but if it's not defective, there's no point.

Do you have negative rail voltage on the center leg of the sf163a?

Do you have positive rail voltage on the center leg of the fep16bt?

[mike49504]

i have + 31.86 on the u1620 had to replace the fep16 bt it was blown

and i have -26.11 on the other

[Perry Babin]

The voltages are not as close (in absolute value) as I'd expect. Place your black meter probe on a non-bridging speaker terminal and measure them again.

With the black probe on the same point, what DC voltage do you have on the power supply pins of the op-amps?

[mike49504]

u1620= 32.34
s= -26.18

i havent measured the op amps yet the power supply fets are getting red hot

[mike49504]

ok here are the readings sf163a= -26.18 mur1620= 32.34

lm318n
Pin1= -4.33
pin2= -6.28
pin3= - 5.03
pin4= -14.49
pin5= -3.62
pin6= -2.34
pin7= -1.61
pin8= -13.63

the other lm318n

pin1= -5.03
pin2= -8.33
pin3= -7.16
pin4= -14.58
pin5= -4.35
pin6= -2.32
pin7= -1.61
pin8= -13.88

[Perry Babin]

Are these in the audio section? If so, you should have positive voltage on pin 8.

[mike49504]

ok i have negative readings on all of the opamps so i checked the Mur1620 again and the new one i just put in is blown.

Wondering what might be causing theese to blow

[Perry Babin]

The rail voltage was OK so the 1620 must be OK. You need to find the regulators. I don't know the amp. Post a photo if you can't locate it.

[mike49504]

i saw some broken solder connections on the driver boards gonna fix them

Also there is a tlo74cn in the amp and that to has no positive voltage on it

The fets were hacked up but they still were good but a hack solder job so im gonna fix thoose nd fix the broken solder connections on the boards then go from there ill try to get my camera to take a decent pic of the amp cause all i see is the drivers for the outputs and on the driver boards just transistors like 2n something