[amsat-bb] Re: G5500 Elevation Rotator Short Circuit?

Fri Oct 14 10:40:05 PDT 2011

The az on my 5500 quit working abruptly lst week. Disgnosis was fairly easy. I went out side and noted that the xyl had cut the az cable with the ztr.
73
George
WA5KBH

-----Original Message-----
From: "Tim Cunningham" <tim_cunningham at charter.net>
Sent: Thursday, October 13, 2011 15:46
To: clive at g3cwv.co.uk, "amsat" <amsat-bb at amsat.org>
Subject: [amsat-bb] Re: G5500 Elevation Rotator Short Circuit?

All of the failures were specifically attributed to either a stuck relay in 
the control box, a manual switch sticking (not releasing) on the front rotor 
control panel, and a software or computer crash that continued to drive one 
of the up, down, left, or right control lines.

73,

Tim - N8DEU

----- Original Message ----- 
From: "Clive Wallis" <list1 at g3cwv.co.uk>
To: "amsat" <amsat-bb at amsat.org>
Sent: Sunday, October 09, 2011 11:50 AM
Subject: [amsat-bb] Re: G5500 Elevation Rotator Short Circuit?

Many thanks Tim for your comments.  From what you've said it sounds like
a faulty motor.  In the ones you've repaired have you been able to
determine the cause of motor over heating?

The problems I've had in the past have always been due to water getting
into the units.

73    Clive    G3CWV

Hitchin, North Hertfordshire, UK

On 07/10/2011 18:50, Tim Cunningham wrote:
> 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
>
> -----Original Message----- 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 passes.
>
> 73     Clive     G3CWV
>
> Hitchin, North Hertfordshire, UK
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