Help identifying Potentiometer

[Abody711]

Potentiometer on new lathe appears to be bad. Turn knob half range before lathe starts. Then it jumps to full speed. Turn it all the way down, still full speed. Turn off and back on and is sitting still. If I missed something let me know.
Attached a picture. What I made out is wx14-12 k7 +-5%. Is it rated at 7k? Suggested replacements?

 

[Abody711]

Picture didn’t show

 

[Ulma Doctor]

if i'm reading it right it's a 7k potentiometer.
a 5 or 10 k would work in it's place
i'd go for the 5k- you'll lose a little adjustability but it will serve well

 

[Abody711]

Is that 7k ohms?

 

[CluelessNewB]

Can you make out the number before the K? I suspect it might not be 7K but rather X.7K where X is whatever that number is.

 

[Abody711]

Found this on eBay WX14-12 10K ohm 4mm Dia Shaft Single Turn Wire Wound Potentiometer 3W. I am guessing it is 3. Should I go with a different part

 

[CluelessNewB]

I believe WX14-12 is the style but it comes in many resistance values.

Do you have an ohmmeter? If yes check the resistance between the two end terminals. (This won't tell you anything if it is completely fried but worth a try if it isn't.)

FYI 3.7K is a very weird value. 4.7K is common but it doesn't look like a 4 to me either.

 

[homebrewed]

There's part of a digit preceding the "k". It probably is a 4.7K pot, based on this product page from LMS. It is used on quite a few mini lathe controllers. If the pot has more than 3 pins, it has a built-in switch.

The value probably isn't critical if it is used as a voltage divider. If it's used as a variable resistor, it probably is necessary to go with a pot that more closely matches the OEM part.

 

[Abody711]

Tested. Shows 9k

 

[matthewsx]

Hi and welcome

Is the machine new?
Or just new to you?

If you just bought it I would definitely check with the seller about a warranty replacement, I'm assuming the pot is part of a larger control circuit and it might not be the real problem. There's a guy who does board repairs on these things, https://olduhfguy.wordpress.com/about/ that others have used if you want to go that route.

Since you haven't stated the troubleshooting steps that determined the pot is bad how do you know it's actually the problem? I just hate to see you buy something off eBay, wait a week to get it, and then find out it's not actually what you need.

I also see Ulma Doctor has already given some advice on your other thread.

they have DC motors in them.
the variable speed drives on these lathes are unfortunately kinda poor.
they do the job most of the time, but since they are made to a low price point- expect some problems down the road.
all is not lost, you can always replace the faulty stuff with another form of PWM ( pulse width modulation) controller for not a lot of money when calamity ensues

If I were you I would contact the seller and tell them how disappointed you are that their brand new machine doesn't work right. Don't tell them that you have taken it apart, but do let them know you want a replacement. They will take a while to get back to you and you will go back and forth but they will not want you to ship it back to them so you can ask for a partial refund.

Then do your research and replace the whole control system with something better, you really don't want to be chasing this problem since accurate speed control is critical to using the machine. You may come out with a better machine and a little cash back in your pocket.


john