Beta Bass hum

[Turk Bloodly]

Hey hey,

I have a beta bass that started humming.  When I turn it on I can play for a few seconds, then the input LEDs go dim or out and there is a terrible hum.  I can jiggle the input cable and it will sometimes work again (i've also tried hitting it with so so results).  I have another beta bass with simaliar input jack problems:  plays for a second or not at all,  input LEDS go dim, except there's a high pitched shrill noise instead.  I've noticed the 3 input jacks on  Beta amps are really close together, are they prone to be problematic?  Any ideas?   Thanks, jared

[JoeArthur]

The beta series does use "stereo" jacks - one side of the stereo jack is expected to make contact with the plug and be grounded.  This grounding is necessary for the input switching (aka channel switching) to work properly.  

It sounds to me like your jacks may be weak (the spring metal that makes up the inside of the jacks)... or they may have some buildup of corrosion that prevents a real good contact from being made.

The closeness of the jacks wouldn't be causing the oscillation problem.

[Don T.]

Hello;
 The input LED's are hooked to the +-15V supply. If they are going dim you have a problem on you power board. Sounds like a bad filter cap to me.