Problem with factory amp in '90 STE

[GutlessSupreme]

I was in the TSTE the other day getting some work done. I had the factory radio turned on and all was fine. I turned it off for a second, then turned it back on (i don't remember why), but when it came back on there was an awful loud/deep humming/pulsing coming from the rear speakers. Kind of like that sound they make when the battery's running really low but a lot more constant and louder. I couldn't figure out wtf it was, finally I unplugged the factory amp it it went away.

 

I swapped in my Sony headunit from the Cutlass and got it all nice and tucked in. Sounded great, until I plugged the amp back in. same deal. It only does it with the radio on, not CD.

 

I swapped in the amp I still had from the TGP and it sounds fine. But here's the thing - the TGP amp is missing the channels for the rear speakers (comparing amp to FSM). The pins are just empty holes. So I still don't know if it was a problem with the amp or if it's something with the rear speaker wiring. The slider on the driver's door (name escapes me at the moment) doesn't make any noticable difference, though I think that makes sense seeing as it's missing the rear channels. It also didn't make a difference on the STE amp with the humming (it did work normally before).

 

So anyway, sorry for rambling. Do you guys think I need a new amp? Does this sound like a short to ground problem with the wiring? I really don't know what to look for in this department.

 

Also, my resoldered RKE box pisses me off, but that's another story I think. Resoldering, cycles all the locks, cycles again when programming, then it may work for a second or two after disconnecting the programming wire, but only for 1 given button (tried two remotes). I think the the joint for power to the ROM to save the keyfob ID is bad, but that's just a guess. Tried resoldering again and same deal/worse.

 

ps- not getting an aftermarket amp, please don't chime in saying "just get an aftermarket amp."

[GutlessSupreme]

fuck me, wrong forum.

[GPX]

Not a car stereo expert, but I've messed with a lot of stereo gear over the decades...Your story is pretty confusing, but I'd guess that a componant got fried (a cap?) in the amp if other amps don't make the noise. Short to ground causes fuses/breakers to blow. 17 year old amps can go at any time, and as you probably know, they are not worth paying to fix as just to get them on a bench costs more than the unit is worth. First I'd pop open the unit and see if there is anything visibly cooked, then see if you can figure what it is and what value it is, then see if you can replace it. If not, it's a trip to the junkyard I think.