The Asong AS-250 is famous for burning out its speed pot, and mine was
no exception. I replaced the speed pot assembly twice with the factory
repair part (provided by Shars Tool), and the new pots also failed after
a short time, so we have a design problem. Shars was going nuts with
the resulting warrantee repair hassle.

Autopsy of the failed post showed that the carbon-film resistor element
was burned. apparently by pulling too much current from the wiper. The
failed pots claim a 2 watt rating, but this is not what one can pull
from the wiper it would seem.

So, I replaced the carbon-film pot with a 10 Kohm 5-watt wirewound unit
made by CTS, about $3 each (Digi-Key CT2159-ND).

This required fabrication of a new shaft extender-adapter of brass, to
connect the 0.250" pot shaft to the 6mm knob socket about 3" away.

The power drive now works, after about two years of neglect. We will
see if this fix lasts.


Joe Gwinn