Diagnosing and possibly Fixing my School's Amp

Discussion in 'Amps and Cabs [BG]' started by Mud Flaps, Dec 15, 2003.

  1. Mud Flaps

    Mud Flaps

    Feb 3, 2003
    Norton, MA
    The amp at school is very old. It's an Ampeg RocketBass amp. I think there's a problem with the -15dB jack. It sounds fine for a while then cuts out at random times. When this happens, only the bass connected to the -15dB spot cuts out. How would I go about diagnosing what the problem is? Then, how would it be fixed?
  2. Does it cut in and out when you wiggle the jack?
    If so it's probably just a cracked solder connection.
  3. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    "Only the bass in the -15db jack cuts out" . . . are you implying that you are plugging TWO instruments into the amp at the same time??? If so, THAT might be your problem.

    If you mean ONE bass at a time plugged in, and it only cuts out when using the -15db input, then yes its probably a cracked solder connection or a crack in the curcuitboard related to that input jack.
  4. Mud Flaps

    Mud Flaps

    Feb 3, 2003
    Norton, MA
    No, I am, indeed, applying that we plug in two basses at the same time. Actually, we do it a lot. If you need any more information on this, post. I can tell you though that this amp is very old, it was the school's first bass amp, and it has been done for probably over a decade now.
  5. miccheck1516

    miccheck1516 Guest

    Feb 15, 2003
    umm, i dont think your ment to do that...
  6. Chasarms

    Chasarms Casual Observer

    May 24, 2001
    Bettendorf, IA USA
    It is most likely that the amp has two inputs wired parallel with a passive resistor on one of them to pad the hotter input signal.

    Plugging in two basses won't hurt the amp at all.

    If the padded input is failing, it could be the jack or possibly the resistor itself failing. You'd just have to break it apart and check it out. A schematic of the design would certainly help. You need to know the correct values of the resistors, etc. If it is all done on an integrated circuit board, it may be tougher to figure out.