[TowerTalk] Troubleshooting HamIV rotor and controller

[Dave Hachadorian]

You may have opened the clockwise limit switch AND the brake wedge may be 
stuck.  The usual way to overcome a  stuck brake wedge is to rock the 
antenna in one direction or the other to free the wedge.  If the Cclockwise 
limit switch is open, you can't rock the rotor clockwise.

To bypass the Clockwise limit switch, jumper terminals 5-8 on the 
controller.  Then you can briefly rock the antenna clockwise, and then turn 
it CCW out of the limit switch.

Dave Hachadorian, K6LL
Big Bear Lake, CA


-----Original Message----- 
From: Gary Slagel via TowerTalk
Sent: Sunday, July 12, 2020 1:49 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Troubleshooting HamIV rotor and controller

Hi guys,
I have a HamIV rotor that's 4 or 5 years old and a companion controller that 
has an aftermarket brake release delay installed on it.   Yesterday the 
rotor quit turning.  When I turn on the rotor control the light comes on, 
the needle swings to the far right which is right where the rotor is turned 
to.
I've checked the fuse and its good.  I've been through the HamIV manual 
troubleshooting section and measured voltages and resistances and come up 
with the following anomalies:
With controller plugged in and powered on and all terminal wires removed: 
manual says the needle should remain on the left hand S but mine swings to 
the right
        All other voltages described in manual look good except terminals 3 
and 7 should show 13VDC but show zero

With controller unplugged and terminal wires removed:          Resistance 
across line cord is 4.5 ohms with brake lever depressed
        All other resistances seem consistent with troubleshooting 
suggestions except they are low (1.5 instead of 4)

Resistances measured on the control cable:       These all seem reasonable 
compared with where the manual says they should be except the resistance 
across the entire pot switch (term 3 and 7) is 290 instead of 500. 
Resistance across Pot Arm to +end and -end total 290 ohms at 1 ohm and 289 
ohms.

Just hoping someone might have an idea where to look next.   My next idea is 
crank down the tower, look at connections and listen for noise when hitting 
the brake and turning levers.   Next, beam off and rotor onto the bench to 
see if it works with another cable.
Thanks for any thoughts
Gary SlagelKT0A

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