[amsat-bb] Re: G5500 Elevation Rotator Short Circuit?
tim_cunningham at charter.net
Fri Oct 7 10:50:50 PDT 2011
The common failure of the motor windings is caused by heat which causes the enamel coated wire to breakdown. When the enamel breaks down an inner winding short results.
I have successfully rewound motor windings on these rotators just to say it could be done, but it takes some work (not recommended).
I have never seen one of these motors with an open winding. The failure mode on the 8 that I have repaired were always enamel insulation breakdown as a result of overheating.
Tim - N8DEU
Sent from my HTC Tilt 2, a Windows® Mobile phone
From: Clive Wallis <amsat-bb at g3cwv.co.uk>
Sent: Friday, October 07, 2011 11:35 AM
To: amsat <amsat-bb at amsat.org>
Subject: [amsat-bb] G5500 Elevation Rotator Short Circuit?
I wonder if this is a known fault. Recently the fuse on my G5500
blew. The problem seems to be a short on one of the motor circuits.
Checking the DC resistance at the control end, the resistance of one
winding is 1.2 ohms, whereas all the other windings are 4.6 ohms.
I could understand a motor burning out and going open circuit, but a
short circuit seems less likely. I'm wondering if it could be a short
on the cable at the rotator end, where it is subject to much bending.
There's about 15 metres of cable.
Any thoughts would be much appreciated. Unfortunately, at the present
time I'm not able to inspect the rotator. It's stuck in the horizontal
position, so I will still be able to use the antenna for low elevation
73 Clive G3CWV
Hitchin, North Hertfordshire, UK
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