Pfaff Sewing Machine Foot Pedals

[Bob S.]

On a previous thread ( Control Pedal Issue) Pfaff 1222 sewing machine foot pedals were discussed. It was determined that the proper foot pedal used a 20K potentiometer. I also have a Pfaff 1222 but an earlier version. No one seems to know what value potentiometer is needed in the foot pedal for the machine that I have. I have some input that a 150k potentiometer is needed but no one seems to sell one or have any information about one. There is a trim pot in the electronics on the machine. Is there some way to check the pedal input to the machine electronics to determine what size potentiometer is needed? The machine regulates the motor speed by thyristor phase control.

 

[MikeMl]

If it it really a three wire potentiometer as opposed to a two wire rheostat, then the actual end-to-end resistance will likely not matter much. I would just go to the junk box, grab several pots, grab some clip leads, and it would take about five min. to figure out what would work...

 

[Bob S.]

Thanks Mike for the quick reply. The foot pedal (3 wire potentiometer) does not control it very well but there may be some issues with the motor control board. There is a blown paper capacitor on the board. I ordered a new capacitor from Digi-key as well as a 150k potentiometer and will try again with these new components.