Kicker ZX.750 Cycling in&out of protect mode

[Perry Babin]

Are you sure that 9, 10 and 11 were all positive voltages?

[shawn111493]

Originally Posted by Perry Babin

Are you sure that 9, 10 and 11 were all positive voltages?

I retested all of them again. Pins 9, 10 are negative. but 11 is positive.
LM361

Pin 1: +12.13
Pin 2: 0
Pin 3: -7.58
Pin 4: -0.56
Pin 5: 0
Pin 6: -12.06
Pin 7: 0
Pin 8: +2.95
Pin 9: -1.56
Pin 10: -1.81
Pin 11: +1.59
Pin 12: 0
Pin 13: +2.95
Pin 14:+2.95
__________

[Perry Babin]

That looks OK.

Post the DC voltage on U11 and U13.

[shawn111493]

U11

Pin 1: -10.5
Pin 2: 3.58
Pin 3: 0
Pin 4: -12.14
Pin 5: 0.42
Pin 6: 0.40
Pin 7: 4.28
Pin 8: 12.06


U13

Pin 1: 0
Pin 2: 0
Pin 3: 0
Pin 4: -12.08
Pin 5: 0
Pin 6: 0
Pin 7: 0.63
Pin 8: 12.09

[Perry Babin]

U11 may be defective. Can you easily replace that IC?

[shawn111493]

I have soldered before but nothing this small. What exactly does U11 do and what would make it go bad? Im just curious.

[Perry Babin]

U11 is part of the servo/feedback circuit, if I'm not mistaken. I don't have the schematic diagram.

There's no way to determine what caused it to fail. It may not have failed but from the numbers you posted, I think it's defective. I could be wrong. The voltage doesn't always indicate conclusively that an IC has failed.

[shawn111493]

I just replaced U11 and everything went well. Easier than what I thought. I retested it and I am still getting the same voltages give or take a few like 0.03V. I repleaced with a brand new tlo72c. Any other ideas about this board?

U11

Pin 1: -10.5
Pin 2: 3.58
Pin 3: 0
Pin 4: -12.14
Pin 5: 0.42
Pin 6: 0.40
Pin 7: 4.28
Pin 8: 12.06


U13

Pin 1: 0
Pin 2: 0
Pin 3: 0
Pin 4: -12.08
Pin 5: 0
Pin 6: 0
Pin 7: 0.63
Pin 8: 12.09

[Perry Babin]

Remove the LM361. Be careful not to damage the board. Make sure that all legs are completely free before pulling it out.

Find a point near the LM361 that reads 0 ohms to the negative speaker terminal.

Connect a jumper from pin 11 to that point.

Do the relays engage and remain engaged?

Post the DC voltage on pads 3, 4 and 11 of the LM361.

[shawn111493]

Originally Posted by Perry Babin

Remove the LM361. Be careful not to damage the board. Make sure that all legs are completely free before pulling it out.

Find a point near the LM361 that reads 0 ohms to the negative speaker terminal.

Connect a jumper from pin 11 to that point.

Do the relays engage and remain engaged?

Post the DC voltage on pads 3, 4 and 11 of the LM361.

I removed LM361 successfully.
Without a jumper wire on pin 11 the amp cycles on and off but no red lights. With a jumper wire on pin 11 to a point on the board the relays engage and the amp stays on in green mode. Im reading 0.03V across the speaker outputs.
Pin 3 -10.68V
Pin 4 0.0V
Pin 11 0.0V