Hi all
New member here and hoping the collective brains on here can help me , I have converted an industrial sewing machine motor running my lathe to a pot for better speed control, my problem is that only a small part of the pot does anything, the motor is a jack 513A originally it was foot operated, there are three wires ( Red, Black, Green ) I have them connected to a single turn 10K pot as follows red to terminal 3, black to Terminal 1 through a 3K3 resistor and green to terminal 2 wiper , terminal 1 being ccw looking from the front , I would like more of the pot useable because at the moment only about a 1/3rd of the pot is usable , is there any way to achieve it, I must say I am not in anyway electronically minded.
Thanks in advance Dell

 

Welcome to AAC!

We can help you with your problem but we need to know more about the motor, voltages and current.
Start by telling us the make and model of the sewing machine. Show us pictures of the motor, the foot switch etc.

We will have to assume that this is a DC motor and the pot controls some power circuitry to drive the motor. We need to get more information about all of the above.

 

Thanks for replies the motor is a jack jk513A , inside the box that originally connected to foot pedal was just a circuit board with one small black component with three terminals on it that the red, black, and green wires connected to and the leaver moved a magnet over it, the diagram is how the potentiometer now and I am given to understand that it’s 160v dc.

 

Try a jumper across the 3.3k resistor,
What is the part number on the 3 legged device?

 

Hi if you mean the part number of the potentiometer this is it
https://cpc.farnell.com/bourns/93r1...-linear-10kohm-10/dp/RE07608?CMP=TREML007-005.
Not sure what you mean by a jumper across the 3.3k resistor
Thanks for replying Dell

 

No the 3 legged IC device on the PC board.

 

No the 3 legged IC device on the PC board.

Sorry but I can’t see anything on the IC thing only some writing on the board.

 

Is there anything on its reverse side?

 

Is there anything on its reverse side?

Not that I can see it’s just blank

 

So it appears to be a proximity sensor, activated by the magnet.
Looks like one of the Honeywell SS400x series?