cargasm66

I recently bought a used Planet Audio P400.4s (100x4RMS) amp. I ran all cabling and stuff, and made sure to route it well. I have good grounds, but whenever I put a RCA in, the amp goes in to Protect mode. It doesn't matter which input i put it in, and does it immediately when I put even one RCA jack in. I ran another set of RCA's over the seats to the radio, to test, but it still does it.

Is my amp fried? Even if it is, it'd only cost $100 for PA to fix it, and I got a screamin deal, so it wouldn't be the end of the world, but I just want to make sure it isn't a wiring problem first.

Thanks!!

~Chris

treeohfive

thats odd, id have the amp checked, it only goes into protect mode when it gets too hot or over powers the speakers.....

recheck all your wiring though, make SURE no wires are touching any of the metal on the car.......could be causing a short

cargasm66

But then shouldn't it go into protect as soon as it gets power?? when there's power, but no RCA's, it acts as normal as possible without any inputs. Green light, no pops, doesn't get too hot too fast. But as soon as the RCA barely touches the input, bam, Redlight. Then as soon as you take it away, the red light goes out. That's why I ran a set of RCA's straight from the headunit to the amp, without actually going thru interior panels. But the same thing happened

Frick, the more I think about it, the more i think it's fried like an egg.

~Chris

treeohfive

takr the amp and get it checked....or hookthe amp up on someone elses system that works. see what happens

NEEDAZ

Most amps will go into protect for one of three main things. One is heat, not your problem. The other two are current, and bias (sometime called DC offset). I think your having a problem with one of the last two. That it is only a problem when the RCAs are plugged in is odd but not unheard of. The amp may not be seeing an offset problem until there is some signal going to it.
But before we condemn the amp you should be checking things like the ground at the HU and at the amp. The outside conductor of the RCA cable is at the same ground potential as the HUs ground and the amp “expects” to see it at the same potential as the ground at the amp. If there is a significant difference that could be the problem.
And let’s not forget the HU itself. See if you can have a friend pull close to your car and run the RCAs from his car to yours. Why? Well sometimes if the ground at the amp is bad it can damage the HU. What happens is if the ground at the amp is bad it will try to ground itself thought the ground in the RCAs that ground though a little trace on the PCB in the HU. If the amp tries to pull all of its current though the RCAs that trace will burn open. Now you end up with some spurious DC on the RCAs and that could be the problem.
So more trouble shooting is what you need to do now.
First check ALL the grounds, amp and HU.
Then get some signal to the amp from a different source.
I would also try it with the speakers completely disconnected.
(Not always a good thing to do but THIS amp will be OK like this.)
DON’T disconnect the ground from the amp.
Let us know what happens…….

ScrapMaker

I would break it all down and make it simple... test the wiring at the amp, 12 volts good... now go and hook up your speakers, making damned sure that the wires to not cross outside, or inside the box... also make sure the voice coils are not hooked up wrong--the same problem can occur. Next go and find a walkman, or mp3 player, use the 3.5mm to rca stereo cable, and feed it DIRECTLY to your amp. Run the walkman on batteries and keep the volume kinda low at first... give the amp its remote power, by turning on the h/u or whatever, then give it a whirl. If it works, then you know that your RCAs from your amp are bad, or maybe the rca connections on the back of your stereo are bad. Try switching the rcas from Front/Rear/Sub to see if it ever works.

One thing to remember for all amps, is that you NEVER hook up the RCA's first if the stereo is already on, it can total an amp... for instance if you disconnect your subs while the amp is on and hooked up the h/u... can detonate the insides...

good luck

-Steven