Replacing pot on Multivox M64 ...

[saccov]

I'm new to the forum but have been playing guitar and messing around with equipment for a while.  I came upon a late '70s model Multivox M64 amplifier that an uncle gave me years ago.  There was a terrible scratch in one of the volume pots.  I think that I need to replace it but can't find the correct pot to replace it with.  I have tried the internet searches but only found comparable materials.  Any help out there would be greatly appreciated.  This is a kick-ass forum by the way!!

Sacco

[J M Fahey]

Hi Saccov.
Get a multimeter.
a) if the pot is wired to the board: unsolder all 3 wires, put the knob half-way ("5" on a 0/10 scale", measure the resistance from the mid pin to the left one, and from center to right one, post here your results.
b) if the pot is soldered directly to the pcb: desolder it *very carefully* , don´t destroy the board, use a good solder sucker, solder wick, etc. The board "is" the amplifier, everything else is generic and can be bought over the counter.
Measure and post  as above.

[saccov]

Thanks J M.  I'll get to it probably on Friday as the amp is located several miles and I have a young toddler which takes up the majority of my time.  Just a follow-up question.  The pot is soldered in five spots (kind of a 3X2) look with three soldering points in front of two others.  Most of the available pots I've found have six or three posts for soldering.  Don't know if that helps you.  When I get over to see the amp again, I'll post the results from there.  Thanks so much.

Sacco

[teemuk]

The additional solder joints are (most likely) securing the potentiometer's case to the board as well.

The problem that you already encountered is that not all potentiometers have the same dimensions. There can be quite a lot of variation in overall dimensions, shaft's length, diameter and shape, pin spacing and style etc.

Not only do you need to find a potentiometer with matching resistance and taper, the part also needs to fit to the existing PC board and the chassis. If you can't find an exact replacement you have to be creative to make the part fit.