Tone control replacement - what do I need?

[Coconuts 500]

Hi! I am having some problems trying to find a correct replacement potentiometer. I have an amplifier where the bass tone control shaft is broken off. It's a dual 100kohm pot (six pins total), and it has ten positions where it snaps to (this is not important). The top position is "flat". The dimensions are very standard and the shaft is knurled. What type do you think I need? Thanks a lot in advance.

 

[DF96]

You need the same type as you have. Could be linear or log, depends on the circuit. You may be able to find a generic pot which fits and works OK, or you may have to buy the exact spare part from the manufacturer.

 

[godfrey]

There's a few here at Mouser., assuming you want linear.

 

[Osvaldo de Banfield]

If you can, post a circuit, or tell us if the circuit is passive or active (Inside a NFB loop, like Baxandall). If it is passive, you need a log pot or "B" curve. If it is active, you need a linear one (A curve). If you don´t have a circuit, look if any pin of that pot goes to ground, surely indirectly though a resistor. If it is true, the circuit is passive.

Good luck.

 

[yai]

Hi,
if that pot is electrically OK, you measure 100kohm from end-to-end and 50kohm from both ends to the middle if its linear. Otherwise its logarithmic. Depending on where you are located, don't trust A or B characteristics: in germany and other parts of europe, lin=B and log=A but this was just the other way round a couple of years ago. This is the consequence of trying to standardize everything.

 

[Coconuts 500]

Thanks for the ideas, guys. I will examine it more the next time I have it open.

I did omit some info before. Seems it actually says B on it. But like what Yai said, when I googled around for info on potentiometers, it basically said that A can be both, and B can be both. Very confusing.

The pot in question is a Japanese ALPS pot, from the late 70's. What could B mean, at that time and place?