I need Help.....

Discussion in 'Amps and Cabs [BG]' started by Spearhead, Oct 14, 2002.

  1. I'm in desperate need of help. My old amp is giving me some problems. Its an old Acoustic 200 w, 120volt (60 cycle) solid state head that powers a 2x15" cabinet. The problem is that I can turn it on and the little light comes on to indicate that power is being supplied, but no sound is created. The instrument cables are fine and the cabinet is fine. The only clue I have is that I get no feedback from touching the line in cord (the one that goes to the bass), which normally makes staticy noise if in contact with anything. What kind of diagnostics can i run with a multi-tester? My budget and the lack of any good electrical technician that specializes in this in this town are forcing me to do this on my own and so any help would be greatly apprciated. A thing to note would be that it was working great last friday and I got back home form being out of town last sunday and it began behaving like I described above. This would lead me to believe that its something simple. Also I checked the fuse and its fine. Once again any help would be greatly appreciated.
  2. Jason Carota

    Jason Carota Gold Supporting Member

    Mar 1, 2002
    Lowell, MA
    What about the cable going from the head to the cab? Is it still making solid contact on both ends? Could be that the contacts are dirty or maybe the cable itself is dead.
  3. All the cables are fine. Its something within the amp. I have opened it up and the circuit is intact, but for some reason the line out to the bass is whats not working.
  4. Yeah, i think you should leave it anone until you know exactly what's wrong, then go about fixing it.
  5. seamus


    Feb 8, 2001
    Though Psycho Bass Guy's advice may sound over the top, he's right.

    You don't want to go poking around in there without the experience necessary to avoid injury, let alone diagnose and fix the problem.

    I know you mentioned it's not an option at this point, but I recommend seeking out someone with adequate experience to service your amp.

    Like he said, we'd rather have you around. Having said that, best of luck with a remedy to your problem.
  6. well I have opened it up and examined it in great detail. An electrical engineer told me that 99% of electrical problems are related to transistors and after I told him what happened to my amp he suggested that it probably is that. Because it is a dual channel amp it has four transistors. Another thing i noted was that 3 of the larger resistors on the main circuit board were extremeley hot and one was even discolored and turning white. A broken tansistor has the ability to do this. So, today i am going to to buy the resistors and tansistors and replace them myself. Hopefully this will work but if it doesn't I will have to do some serious research.
    It is very true that i could hurt myself by just fooling around in there, but thats why I asked for your guidance. After doing some research I do have a general understanding of basic electronics and believe I am very much able to fix this on my own. I like learning things and understanding how something this important to me operates and it was because of that that I really wanted to fix it on my own (there is also of course the $ factor). It is my belief that if anyone starts using their head their is very little they cant accomplish and it is because of that belief that I think I have progressed so far in my musical ability since i started 2 years ago. Thanks for the input.