When I plug in my RCA's into my MTX 280 amp, they sometimes make the subvibrate really hard (Even with the volume turned down).When they do this, I can push my finger between the RCA inputs on the amp and it will stop. It's like the RCA connection inside the amp is dirty or bad. Also today while driving the sub started making a REALLY high whine, so I pulled the RCA's out to cut power. What is the deal? Are my RCA's bad? Is it just a bad ground? Can I clean inside the RCA reciever on the amp?

 

You almost covered all the reasons this could be happening.
Lets start with simple little things.
Check the amp's ground, make sure its solid, no paint between the ring terminal and body.
I hope your rca's aren't ran right next to your power wire because that can sometimes pick up noise.
Check your ground wires under the hood, from the block to firewall, block to battery, battery to chassis etc. I had one break off on my old s-10 and my system sounded like crap when i used anything high current (airbags, system, power inverter, etc)
If all else fails try running a new set of rca's to test. If new ones sound fine then your old ones may be bad.
If that still doesn't work try hooking someone elses rca's from another car to your amp. If it still does it your amp may be on its way out, sh*t happens and electronics break all the time. Heat, humidity, cold, condensation, dust, vibration, and tons of other factors take their toll on electronics over time.
I test amps all the time at work and its just a game of trying to figure crap out and sometimes its a simple fix, and sometimes its a bad amp.
Good luck.

 

it sounds like you have a set of rca's thatis going bad. Try a new set and see what you get but I would also check your decks ground.

 

Try also running the RCAs OUTSIDE the car (just to test, as you obviously wouldn't leave it like this). This should help you figure out if the RCAs are bad or if you just have noise issues.

Good luck.

-Jordan

 

dingy ur sending feed back thro ur rcas!!!! is ur can on when this happens? first change ur rcas if there cheep next dont work on ur car wail its runing!!!!! do not run the rcas out side the car it ill have no effect.

 

LOL. Riiiight.

-Jordan

 

he is checking to see if the rca's are bad. Running a temp set either above the carpet or outside the car isa 5 sec way to test rca's.

 

My opinion is the amp is bad. I have 2 mtx 225ho's in my gt. these amps are around the same age as yours, "old school" .I use them to run my focal utopia's. Bridged one per side, they are great amps, but I had the same problem. sent them to be repaired, and the problem went away!