Hi. First time posting here. I found this forum looking for tips on troubleshooting a solid state guitar amp. Hopefully someone here will be able to help me with this thing.
A buddy of mine got a little 2x8 solid state guitar amp given to him but it has something wrong with it. I tinker around with a lot of things so he dropped it off here hoping I could figure it out. I really don't have a clue as to what's wrong with it. It's an RMS500RC, made in Korea, 2x8" 2 channel amp with reverb and chorus. I've never seen one before. The problem is that when the 'high' knob is turned up, it starts crackling until about halfway thru the travel of the pot. From half to full the amp just hums and there's no output other than the hum. I took it apart and had a look around but didn't find any pcb cracks, bad joints, etc. I did notice a burned plastic washer that goes between one of the ic's and it's mounting screw. This amp has two TDA2030's mounted to the back of the chassis. The burned washer (or insulator?) is white plastic. That's the only sign of overheating that I could find. All controls work good except this issue with the 'high' control. Output to both speakers seems fine and output from the line outs seems fine.
I recorded a sound clip by connecting one of the line out's to my sound card. Maybe it will be helpful. In the sound clip I flip on the amp, start playing some chords, and begin slowly turning up the high control from zero to halfway. I'm strumming chords all along the way. At 10 seconds you can hear the crackling starting. At 36 seconds you can hear the humming. I increased the volume of the humming to make it more apparent. The hum is very apparent when running thru the amp's speakers but for some reason it's very low volume when using the line out's alone. Sound clip is here (RMS500RC.mp3): http://sellyoursoulformusic.googlepages.com/travis%27smp3%27s
I can solder, I know how most components work and how to check them (except ic's), but I don't have a clue where to go from here. If I fix, bonus for my buddy. If I don't, bonus for me. I'll have a complete chassis with a reverb tank and speakers for an amp project.