Noisy Treble Boost on Concert Bass

[jwibbens]

Anyone with suggestions on tracking down the cause of a noisy Treble Boost circuit in my Concert Bass Amp would be appreciated.  It works fine in the off position but creates and scratchy sound during signal input when engaged.  I am in northern Indiana so any other suggestions regarding capable repair sites would also be appreciated.

[JoeArthur]

What year concert bass? Does it have the distort control?

[JoeArthur]

Maybe it doesn't matter. Just be aware I haven't worked on any of the 1975 or newer versions without the distort control.

A noisy bright switch can only be one of two things. One is the switch. The switch on the earlier versions was sealed - meaning it cannot be cleaned. However, it is somewhat unlikely that a sealed switch would ever become dirty. But one possibility is that the switch is just plain worn out and needs to be replaced.

On the earlier versions, since they did have sealed switches, the most likely cause would be the pin connections. The circuit board has vertical pins, and both sides of the bright switch have "lugs" that fit over these pins. More than likely one side or the other has a lug that is loose over the pin.

The best fix is to solder the lug to the pin.

[Johann]

thanks Joe, I was reading this thread and thinking how mine has the same problem, I'll try soldering them on.

[jwibbens]

Thanks Joe...  I will check it out and try your solution