Dead Channel?

[NotoriousPMP]

I just put in 2 Dayton RS125 5" woofers in my dash and 2 pioneer 4x6s in the B-pilars and my drivers side 4x6 isn't working. I took out the HU and soldered the JVC to the scosche adaptor harness so the connections are 100%. I even tried direct wiring the HU harness to the speaker to make sure its not the stock 19 year old wiring. I was doing the subaru install (see my frantic thread) I had another brand new JVC headunit around which uses the same connector as mine. So I hooked it up and the speaker kicked right on. So its the HU. Do HUs burn out channels? If so is it fix able? Should I build up the courage to open it up and look for the burnt channel? What should I look for? Sorry I am such a n00b but at this point I can't afford to buy a new HU and it sounds good with the 3 but all 4 working was 1,000 times better.

also tho if I fade it all the way to the back and the left so power is only going to the 4x6 that doesn't work and turn the volume to 35 you can kind of hear something coming out of it.

[roscoe1129]

I have seen many head units get a cold solder ( a bad solder job) and they will have dead channels or will fade in and out with bumps in the road. I had a kenwood Excelon that had a cold solder on the ground. When it was hooked up to the pre outs you couldnt tell it was doing anything but I sold it to a guy and he just had the speaker level outputs to his factory speakers and everytime he hit a bump in the road it would "pop" thru the speakers.

[NotoriousPMP]

So can I pull it apart and re-solder the the connections on the Left Rear ground and positive? BTW I bought it off a friend who bought it off someone here on the forum my friend never got it to work with the his factory amp so I don't know if it was always like this or if the previous owner blew it. Considering the price I think he may have known. Is there a way to know what I am looking for or should I just follow the pins on the back on the HU to the wires that connect to them and re-do what I can?