TIC ringrotor control box smoke

[Keith Morehouse - W9RM]

After getting the control box hooked up again for my RingRotor, I had an
interesting "failure" and am curious if anyone else has ever had this
happen with a TIC controller.

After plug in, AC power was applied to the box and the meter swung to
the correct direction.  I turned the preset knob and started the motor.

After about 30 degrees of rotation, the meter pilot lights suddenly
increased in brightness, followed immediately by loud component frying
sounds from inside the box and an immediate LARGE cloud of smoke.  Power
off, 4 letter words on...

To shorten the story, the ZNR (transient suppressor) on one of the motor
lines let loose as only ZNR's can, filling the inside of the box with
ash and smoke debris.  Man, it was REALLY smoked.  After checking
(again) for cable errors and removing the remains of the ZNR, the
controller worked just fine.  No problems...

A glance at the rest of the ZNR's showed a part number ending in 220. 
According to my catalogs, that means a max DC voltage of 18V !  The
motor on a TIC runs off a nominal 24V and mine reads 30V when turning. 
Does the controller have a larger ZNR on the motor line or did somebody
screw up and it just took this long for it to blow ???

I'm not going to reinstall a ZNR in the box because I have all the
control lines shunted by them (65 volt rated) at the shack entrance
panel.

Comments ??  The shack is gonna smell like fried ZNR for weeks - those
things are nasty...

Now - back to vanity call s..t !

---------------------------###-----------------------------
PROBE ELECTRONICS 100 Higgins Road, Park Ridge IL 60068 USA
Keith J. Morehouse /  W9RM  / Society of Midwest Contesters
847-696-2828  FAX: 847-698-2045  e-mail: blckhole@ripco.com
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