[TowerTalk] FOLLOWUP--TIC Ring intermittent

[John Brosnahan]

Wanted to thank everyone for their input and provide some
feedback on the TIC Ring pot failure.  The borrowed motor/pot
assembly works fine and the failed unit has been disassembled
for diagnosis.  The failed unit had only been up for a week or so
with very limited use--mostly just the initial testing and it worked
flawlessly until the failure.

The post mortem appears to show now sign of mechanical distress
on the pot that would be associated with going past a stop.  The
back end fixed-connection to the resistence winding just appears
to have failed open.  There is a miniscule connection from the
terminal post to the winding and that had opened up.  Only obvious
candidates for the failure mode are 1) defective pot design  2) defective
pot manufacture  3) overheating from soldering the wire on the 
terminal.  But the exact cause appears to be impossible to determine.

Whatever it is that happens according to the bumper stickers 
seems to have happened here!

Again, thanks for the input.  It appears that this problem is not
widespread.  Will check with the factory about their experiences
later this week and will consider replacing the pot with an equivalent
unit from another manufacturer such as Bournes.

73  John  W0UN


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