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-Breake...
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