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Posted in response to Re: Re: Ultra Tech Speed Control Potentiometer from Chuck Blalock on June 10, 2010 at 16:56:57:

Re: Re: Re: Ultra Tech Speed Control Potentiometer

Hi again Chuck,

I suspect the reason UltraTec won't sell you the potentiometer as a part is that they are using an outsourced speed controller that they also don't manufacture. If they do in fact manufacture "their" speed controllers and won't sell you a replacement pot for it, that really speaks poorly for UltraTec service and customer care.

You should be testing the pot with an Ohm meter, not a continuity tester. A potentiometer functions as a variable tapped resistor. They typically have three leads, two end leads and a tap lead. You should measure the full resistance of the pot between the two end leads, and a varying resistance between either end lead and the tap lead as you adjust the position of the pot control shaft or slider.

Here's a link to a quick primer on pots:
http://en.wikipedia.org/wiki/Potentiometer

The full resistance depends on the value of the pot. A "1K" pot will have a full resistance of approximately 1000 Ohms between the end leads and a resistance varying from approximately 0 Ohms to approximately 1000 Ohms between the tap (slider) lead and either end lead. (Most pots are designed so the tapped resistance cannot be adjusted all the way down to 0 Ohms for reasons I won't go into if they are not apparent to you.)

I don't have an UltraTec or UltraTec speed controller readily available, so I can't directly check what would be required as a replacement pot, if yours has in fact failed. However, there are many UltraTec users on the United States Faceters' Guild List, and several of them are also knowledgeable regarding electronics. Hopefully someone on the USFG list can help you with the specification of a replacement pot for the speed controller in your UltraTec:
http://www.usfacetersguild.org/faceters_list.shtml

Pots can get ratty and do fail completely. Without a definitive test on the pot, it's also possible that your issue is elsewhere in the speed controller circuit (or motor). In any event, it should be repairable by a knowledgeable person for significantly less than the rather pricey $250 cost of a new speed controller from UltraTec. Pots are generally inexpensive, so if you are going to shotgun the repair, that's probably as good a place as any to start.

From Bob Keller - June 10, 2010 at 18:02:03

Message: 69134



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