Rs 2640 stereo system after five years suddenly stopped working. On all of the sources (fm Radio,am Radio, cd player, tape player) it just produced a buzzing noise. I looked this up and it seems to be a common problem with these units. There was ONE suggestion that apparently worked for a few people, and that was to replace the q401 transistor with an NTE382. When I took it apart and looked at the circuit board, the Q401 seemed to have had a darkened area around it, like a little explosion occured. Anyways, I tried replacing it (not with an NTE382) with a 2n3904 and the radio didn't even turn on, so then I tried a 2n3906 and the radio turned on but now with no sound at all, but when I turned it off the speakers made like backfire noise, now I purchased a few more npn silicone transistors on hopes this might fix my problem, should I even try these? Or just order the NTE382 online (I got the rest of them at RadioShack) or am I just wasting my time? I have never worked on a circuit board before, I'm just a poor 22 year old bartender who doesn't want to afford a new radio so any instructions might need to be broken down sort of specifically for me. But honestly, I'm finding this a super fun project. The soldering at least makes it all worth while, haha. Thanks!