AQ 120.4 RCA trouble

[AZaudio]

Issue: Amp goes into protect once RCA cables are plugged in.

Checked RCA shields on the amp, transformer measures fine.

Tried 3 different rca cables from 3 different inputs on my HU Pioneer 80prs...none worked

One of these rca's is going to my M3a and it never had a problem.

Voltage never drops below 13.3. Have not checked ground though.

Stays GREEN when RCA's are unplugged

Also, how do I determine if channel 1 on the amp is the left or right RCA jack from my hu

[AZaudio]

Anyone have any idea?

I unplugged all speakers and left RCA's in which led to the protect light coming on again.

Sometimes, especially when it is not hot outside, it works fine for a brief period of time.

[AZaudio]

Well as soon as it started getting hot outside, this same issue has been occurring. Even in the mornings when amp is completely cool, this will happen. I have knu 4-channel rca's. I am out of ideas, so feel free to chime in

[hazestorm23]

Did you buy it new and have you opened it to take a look inside

[AZaudio]

Bought it used on caco; I've opened it up 4 times atleast now to inspect the guts.

[n8ball2013]

Try a different head unit. More than likely its the amp though

[AZaudio]

If its not the HU, is it possible for me to diagnose the amp somehow?

[AZaudio]

Found the RCA cable wedged on the corner of the amp causing it to ground out because it tore through the rubber. Taped it up, plays fine for a few days, then same thing starts happening. I have noticed the following: alternator whine has been introduced, the red rca cable off of the 4-way rca is the only one that works with my amp. Every other rca connector puts it into protect except the red. It does not matter if it is connected to the correct channel, amp will stay lit. I have tried every configuration from head unit to amp. Therefore I am leaning towards the RCA cables being the problem.