K8DO note--FYI--John W0UN
Hi Barry...
Just went through this, in spades.... I are now a walking, talking, breathing
expert... When the meter follows the preset pot, the problem is in the
direction pot or wiring, not in the control box....
Most likely, is... in descending order:
1. The directional potentiometer wiper arm has gone open (most common)....
2. The potentiometer wiring is pinched/shorted inside of the motor box
(very common)
3. The rotor cable has a broken wire or a shorted wire(s) between the
control box and the motor box.... (less common)
4. God doesn't like you any more.... (I don't know you well enough to rate
this one - though I have heard rumors of sloth, envy, coveting thy neighbors
ass, etc.)
To check the control box....
1. Unhook all five cable leads at the back of the control box.... Connect a
resistor from connector #4 to #5 and a second resistor from #5 to #6....
the directional potentiometer is a 500 ohm unit, so these 2 resistors
should add up to roughly 500... I use whatever is handy in the junkbox in the
100 to 400 ohm range... think I had a 220 and a 330 ohm handy...(if you have
a 500 ohm pot handy, use that... the two outside leads go to the #4 and #6
respectively and the wiper lead goes to #5....) Now power up the control box
and see if the meter follows the preset pot (I'll bet it doesn't) then turn
the preset knob fully CCW and press start and you should get the motor
light... Check motor leads #2 and #3 and there should be roughly 20 volts DC
- notice the polarity... now move the preset to the meter indication and see
if it shuts off... now rotate the preset full CW and press start start
again... check that the DC polarity on the motor leads is reversed... et
voila you have a working control box....
2A. Use the ohm meter on the control cable... the motor leads should not be
shorted to ground or shorted to the potentiometer leads.. there should be a
low resistance through the motor - less than 5 ohms....
2B. Check the potentiometer leads... there should be 500 ohms across the
pot (#4 to #6 wires) and the reading across the #5 to #4 wires plus the
reading of the #5 to #6 wires should total up to 500... they should not be
shorted to ground or to the motor leads...
To Check the motor head - assuming no problem was found above:
1. leave your resistors across connectors #4,#5,#6 as above.... hook up the
motor leads to #2 and #3 ... GET A HELPER.... power up and rotate the motor
CW... stop it by turning off the power switch... Do Not Over Rotate - lest
angels fall from the sky and smite thee! .... Now rotate it CCW, same
rules.... if no problems remove the resistors and hook up the rest of the
rotator cable... it probably will work now....
I found that I had an intermittent open on the wiper lead... probably due to
dirt inside the pot... rotating the beam back and forth a couple of times
apparently dislodged the dirt and it has been fine since... I have a new pot
and gear to install "next summer"....
Cheers ... Denny
At 09:24 AM 10/24/2004, dennis o'connor wrote:
Welcome to the wonderful world of TICed off owners... The ten turn
potientiometer is probably jammed/stripped/broken/shorted/open (most
likely has gone open on one side of the wiper) - however it could be a
control cable wire so go up and look... But, having been up the tower a
hundred times trying to keep an original model 1022 working, I am an
expert at the assembly and disassembly of the motor unit.... Lot's of
interesting new experiences in store for you...
Likely you need to bring the motor box down to the shack and measure the
pot and the switches... A couple of years back I authored a long diatribe
on how to measure the pot, etc., and generally trouble shoot the
motor/control box with jumpers, and an extra pot, yadda, yadda.. I
probably can't find that document now, but a search here or on the web
should bring it up... As far as mine, the rotor is retired after it lost
direction during a contest and the op didn't understand the unit so he
leaned on the manual button and it continued around until it ripped the
hairpin and balun off the beam and then bent an element, doing several
hundred dollars worth of damage...
Denny
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