Kicker DX A1500.1 no oscillation in power supply

[barber02]

I have a kicker amp that gives a green LED when powered up but, there is no oscillation in the power supply, no rail voltage of course, but I see battery voltage at the rectifiers and on the output mosfets, no oscillation there.

Basically the amp makes you think it is functional with the green LED but there no action happening on the inside.

The amp doesn’t even try to start, I usually see a quick spike in current when I connect the remote voltage when the rail caps charge but that is not happening here.

This is only my second kicker amp that I’ve had the opportunity to work on and know very little about them.

Another quick curiosity is that, I noticed that many of the SMD resistors are black blanks. When I measure some of them I get various ohm readings. What’s the deal with that?

David

 

[PapaZBill]

Check the DC Voltage at R5-10 ohm and around the IC16-UC3843. R5 feeds B+ to IV16 Pin 7 and may have opened up because of a shorted C46-22uf 16v, Q5-2045es or IC16.

 

[PapaZBill]

Another common problem is the circuit with Q21-BCP56, ZD9-13v, C69-220uf/16v causing the B+ line to short.

 

[barber02]

I’m feeding the amp 14.55 volts and I get 13.46 volts to pin 7 of IC 16.

I checked for opens and shorts around the other mentioned components and didn’t find anything wrong.

 

[PapaZBill]

Okay, Check the DC voltage around IC16. Check the waveforms at IC16-Pin 4 and 6.

 

[barber02]

IC16 has the following voltages.

1 .814v
2 4.54v
3 .498v
4 saw tooth wave with some DC offset just above ground
5 0.00v
6 dead, no output
7 13.5 v
8 5v

 

[PapaZBill]

Pin 1 is low and Pin 2 is high. Which means that either the UC3843 has failed or surrounding circuitry.

Measure the voltages around Q4-C817, IC13 and IC7(You'll need to carefully probe because of the tight pin spacing), using power ground for the black probe.

Measure with an ohmmeter around IC16,IC13 and Q4, also with black probe on power ground.

Post your results.