I have a Kicker zx750.1 , the amp kicks in and out of protect mode. I brought the amp inside and currently have the cover off the amp and tested with a multimeter the speaker output terminals and this is whats happening. When I power the amp on for the first time it reads 0.0v DC and it begins to clime 0.3, 0.6, 0.10, and so on.. It climes for about 30 seconds until it reaches 1.75v DC and goes into protect mode. It then comes out of protect mode and shoots back up to about 1.45v and climes back up to 1.75v and goes back into protect mode and it just repeats and repeats. Any ideas on it? It does this with or without a subwoofer connected now. Nothing on the board looks bad or smells burnt.
The highest voltage I measured in between the on and off cycles was 5.8V before it kicks back into protect, it looked like it would keep climbing though. And about the input preamp board, the amp still cycles with the board plugged in or not and I still read voltage on the output side. Also noticed that the protect cycles are becoming shorter and shorter so I tested the output voltage again and now I am getting 3-4 volts DC on the outputs. I took notice that two of the transistors are getting warm and the others are cool if you look at the pictures and count form left to right they are numbers 6 & 7 the are the only two different looking ones of the bunch.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I wasn't to sure which set to test and what option for ohms my multimeter should be on. Can you tell me which ones from this picture? I think they are the lower left 5 or maybe the first 5 in the top and bottom rows?? Thanks
An externally hosted image should be here but it was not working when we last tested it.
Post the DC voltage on all pins of the LM361 (U14). Place the black meter probe on the negative speaker terminal.
Look up the datasheet if you don't know the pin numbering scheme.
Copy and paste the following into your reply.
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:
Look up the datasheet if you don't know the pin numbering scheme.
Copy and paste the following into your reply.
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:
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
__________
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.
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.
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
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
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.
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
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