kicker zx400.1 goes in to protectuon mode.

[rdiaz]

Hello everyone, I have a kicker zx400.1 with problems, the amp turns on and produces output signal at low gain when I start turning the gain up the amp goes in to protection mode, if I turn the gain down the amp comes out of protection. The amp come in with R108 (270 ohm) and R106 and R107 (220 ohm) burned, I have replaced the resistors and TL074C on input board.

 

[rdiaz]

Here are some pictures of the amp.

 

[PapaZBill]

I don't recall seeing this on a ZX400.1. I have on other 06ZX mono amps. Take a look underneath the input board you will see a 10uF 160v NP Cap lying down. Inspect it for any punctures from the Gain pot leads. This will cause the amp to oscillate.If this is the case, trim the leads and add a thin sheet of cardboard to add more insulation. You want to replace cap, but may not be necessary.

Let me know what you find. There may be other issues.

 

[Perry Babin]

An example of the punctures on the capacitors (attached).

What if you have no load?

What if you change the level with the signal source and not the gain control?

 

[rdiaz]

I have check the areas you mentioned and everything is ok there, looks like on this model the raise the input board or they used different caps. I have noticed if I let the amp running for small period of time I can turn the gain higher almost to clipping point. I tried changing the level with signal source and is doing the same, I'm doing this without load connected.

 

[Perry Babin]

Does the current draw increase significantly when you increase the signal level (no load)?

 

[rdiaz]

If I add heat with a heat gun to this area I can get full gain.

 

[rdiaz]

The current doesn’t change much, from 1A goes to 1.1A.

 

[Perry Babin]

Heat the components individually to see if you can narrow down the problem component/area.

 

[rdiaz]

Looks like the 551 is bad.

 

[Perry Babin]

That's an LM393.

 

[rdiaz]

Ok, the 551 is just the marking code?

 

[PapaZBill]

The LM393 is the comparator for the OCP over current protection, If the IC fails it would most likely shut down the amp. If replacing the IC does not correct the problem, check for cold solder, resistors out of value etc

Also check that D231-BZG03C12 12 volt zener is not out of value.

 

[PapaZBill]

Q219,220,233-A1661Y and Q231-C4373Y are all part of this circuit and should be checked

 

[rdiaz]

Ok, I will check all of them. Thank you.

 

[rdiaz]

I have checked all the components you guys mentioned and they seem to be fine. Do you know what are the values of Q95 and Q94 they are marked as AL6. Thank you.

 

[PapaZBill]

Q95 and Q94 are KTC3875GR.

D234-1N4148 & R94-56K Ω can be removed one at a time to see if the amp is able to have output when rotating the gain control from min to max.

 

[rdiaz]

Ok, so I removed D234 and amp goes in and out of protection mode then I put it back and removed R94 and know I can turn the gain up and amplifier doesn’t go in to protection anymore. What do you think is bad on the amp.

 

[PapaZBill]

return R94 and Check the DC voltages Q219,220,223,232,233-1661y,Q231-4373y, U231. check the circuit "cold" and then use heat gun so the amp does not shut down and recheck. My best guess is a cold solder issue.