Anyone got a guess? Has me, my builder, and a amp repair guy stumped

[JoshC 10+ year member]

So ive gotten 2 different usx4065s from audioclinic now, both have had the same issue when installed into my truck. Both amps tested fine on the bench before sent, and the first one test fine when it returned. He told 4 others with no issues, so i guess its my truck but we cant figure it out.

So every time ch2 on the rcas is plugged in, power is cut way down to all 4 speakers. Also a buzzing noise can be heard and i can see the cones of my rear speakers moving. It only does then when ch.2 is plugged in. Now if i plug in all rcas and pull the power wire from ch2 they all play fine.

Heres the weird thing, i set my fader all the way to the front so only the ch.1 and ch.2 could be heard. All 4 rcas are plugged in and power wires for ch.1, 3, 4 are connect. So i play a song and then connect the ch.2 power wires to the amp. And ch.3 plays WITH channel 2, power cuts down drastically.

We also tried ONLY connecting ch.2 of the RCAs with all speaker power wires connected. When that happens ch.2 and ch.3 play but at lower volumes then it sound.

What is this???? We checked all the wires and all perfect, checked the crossover for ch.2 its good. Like i said the first amp did this too, sent it back to him and it tested fine on his bench.

My db A5 90.4 is in my truck now having 0 issues, im so confused

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[KyleBechtold 5,000+ posts]

test the amp outside the truck yourself and not rely on him to tell you his fix is good.. easy test.. get a work bench or something you can set the amp on pop the hood and hook a small pos and neg run to the amp from there and have it sit up front.. get 3.5mm to rca inputs and I am sure you have extra speakers lying around somewhere.. hook em up and test it..

 

[DaveVT 10+ year member]

Maybe a bad rca ground in the deck? or theres a problem with that single rca cable?

 

[JoshC 10+ year member]

test the amp outside the truck yourself and not rely on him to tell you his fix is good.. easy test.. get a work bench or something you can set the amp on pop the hood and hook a small pos and neg run to the amp from there and have it sit up front.. get 3.5mm to rca inputs and I am sure you have extra speakers lying around somewhere.. hook em up and test it..

I do have thoughs items, i might give that a shot tomorrow... He said he would refund if i wanted, but i wanted the amp

Maybe a bad rca ground in the deck? or theres a problem with that single rca cable?

I checked the ground on the back of my deck, seemed fine and well intact. Wish i had a spare 4ch RCA to try it with

 

[KyleBechtold 5,000+ posts]

so test it out.. if another amp works perfect in the exact same environment then it seems like an amp issue and not a system issue..

 

[Mitch86 5,000+ posts]

Seems like it has to be the amp if the other amp works fine in the same install. Maybe when they bench tested and it worked, they just sent you the same amp again?