So, why not disconnect the pot, run 2 wires from the internal connection=20
points out to a 5K pot and see what speeds you get at various positions?

Kerry


Dr Skip wrote:
> Olin, I'm not sure you understand. I have it disconnected. The wiper is
> bad and/or the carbon (or whatever they use today) trace is worn off
> inside. I measured the total value at 5k. The wiper doesn't make
> connection internally over much of the travel, at least not well or
> randomly. If you're suggesting total resistance, I have that - not
> difficult. If you're suggesting a way to profile what the values are at
> various degrees of rotation, I'm not getting it...
>
> I did like the idea of a parallel resistor Bob. Lots of ways to play
> with that. Don't know why that didn't occur to me! That's the kind of
> approach I usually take.=20
>
> As far as taking it apart Joe, it's plastic welded together. If I break
> it open, I may just see if cleaning and/or reworking fixes it, with some
> lube to prevent future issues. I'll want to have a good plan for
> re-assembly, because if I go to that length, it'll make sense to just
> fix it if it's fixable. My experience in the past has been that the
> track wears and creates 'dust', which causes intermittent connection or
> resistance values. It's a lot easier when the thing is put together with
> metal tabs or such. ;)
>
> I did look at getting a 'factory' part. As you might guess, being near
> the factory Carl, they don't sell internal components. They're happy to
> sell you another one for a few Benjamin Franklin portraits... Their
> 'schematic' is nothing more than how the accessory parts go together. I
> did find one shop that listed internal parts, although the model
> matching wasn't perfect. Not sure how _they_ get supplied, since there
> is no 'authorized' repair or parts depot. A pot listed as almost $30.
> Minimum order was $40 I think. Plus shipping, etc. It's just a standard
> motor with brushes, pot, switch, and an analog controller inside.
> Sheesh! Pots are a buck. I do notice that the way it's made accommodates
> different parts (long story) throughout, as if they buy in lots and cast
> parts can accept different parts. That could mean different pots
> physically, but the same controller board or same value pot, or perhaps
> the pot is matched to the particular controller board inserted. No way
> to know without talking to the factory and/or designer. The nice women
> on their help lines may be good at recipes, but not manufacturing or
> engineering I'd guess...
>
> If it gets too deep, a $10 Harbor Freight motor controller and a little
> 'bypass' surgery inside the motor base might do it. Not pretty, but at
> least there's a backup plan. ;)
>
> -Skip
>  =20



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