Hi David,
As you found out shaded pole motors do not pull more current when
they stall, they
actually pull less and so they wont blow the fuse, they just sit and cook.
So while your changing the motor now might be a good time to put 2
thermal cutout switches
inside on the windings so this doesn't happen again,it takes two, one
for each direction.
http://www.devale.com/battery-protection/miniature-bimetal-snap-disc.html
or
http://www.pepiusa.com/prod.html
explains them, and you can find them in small quantities at
http://www.allelectronics.com/make-a-store/category/765/Thermal-Fuses-Breakers-Switches/1.html
or at other places...
73
Kevin WA6FWF
On 2/23/2012 6:31 AM, David Palmer KB5WIA wrote:
Hi Everyone,
Well I'll be QRT from the sats for a little while!! After replacing
my UHF antenna on the backyard satellite array, I managed to catch the
(slightly longer) new antenna on the house roof and jammed the Yaesu
G-5500 rotator, ugh! Even though I had replaced the normal 2-amp
fuses in the controller with 1-amp fuses, the azimuth motor still
managed to overheat and burn out.
I disassembled the azimuth rotator, and although the gears, bearings,
switches, and capacitor are all OK, the motor has quite a burnt smell.
Bench-testing the unit with motor removed from the assembly shows the
motor doesn't spin at all in one direction, and spins slowly but draws
high current in the other. Coil windings are in series for
left/right, should be 3.5 + 3.5 = 7.0 ohms, and the right coil is
showing only 1.0 ohms resistance. The azimuth motor is definitely
toast. Fortunately, the controller is OK (both the Az and El sides
of the controller successfully control the elevation rotator).
I just got off the phone with Yaesu parts, and unfortunately the
replacement motor has been backordered from Japan since December. No
estimate yet of when more might come in.
Question to the list: does anyone have a G5500 azimuth rotator with a
working motor available for parts? Or any other ideas for
replacement?
73! Dave KB5WIA
_______________________________________________
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_______________________________________________
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
