[amsat-bb] Re: G5500 az rotor repair

David Palmer KB5WIA kb5wia at amsat.org
Sun Mar 4 11:33:39 PST 2012

Hi Ken,

A couple of things to check.  The resistance of the motor should be same
for both directions, ie between red and black should be around 3.5 ohms as
well as green and black.  Total series resistance of motor should be around
7 ohms.  When mine stalled, the motor overheated and one winding was only 1
ohm, definitely a short.

Other thing to check is that you put the brake back together in right
orientations.  Theres a circular spring inside a nylon cylinder that holds
the metal driver from motor and the white nylon gear with tab.  If the
prongs on the spring are at 10 and 2 oclock, the white tab from gear should
go at 12 oclock and the motor driver wings at 9 and 3 oclock.  Thats how it
is in mine, if orientation like that motor drives gear freely, and gear
cannot drive motor.

I sent my motor down to LA a week and a half ago for rewinding - so far
seems USPS has yet to deliver it, ugh.  Running with elevation control only
right now, with antennas fixed at 270 degrees.  Flipping backwards gives me
a few degrees at 90 azimuth as well, but beamwidth of the yagis isnt great
so not best solution!  Yaesu parts says maybe 4-6 weeks for motors to come
from Japan.

73!  Dave KB5WIA
 On Mar 4, 2012 9:00 AM, "Ken Swaggart" <k.swaggart at charter.net> wrote:

> After a 3 month wait I finally received the replacement for a damaged gear
> in my G5500 azimuth rotor. Replaced the damaged gear, and the gear assembly
> smoothly turns both directions. However, when using the motor the rotor
> rotates to left at normal speed but right at about half speed. It also
> occasionally momentarily stalls when turning right.
> If the motor is damaged wouldn't it affect both directions?  There is a
> slight aroma of a electrical wiring left over from the failure three months
> ago.  Suspect I need a motor replacement, but would like to confirm this
> with the group.  Seems strange only one direction would be affected since
> I'd think the same windings are used in both directions.  A few years ago
> when the motor failed it didn't move in any direction.
> Incidentally, the gear that failed was the plastic gear that the motor
> drives (Yaesu part number PE-8601-010-A). The coax caught on a exposed bolt.
> Tnx,
> Ken, W7KKE
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