Hi All,
In recent weeks I asked about the AZ resistor pot for my G-5500. The unit is 9 years old. The observation was a "bad spot" that appeared to be in the area of 150-220 degs. But it was sporadic...not the same all the time. I suspected a worn spot on the wire contact of the resistor pot...I was wrong!
This weekend I opened it up (azimuth) and was "pleased" to see that the "only" problem was a broken black wire that runs from the center/back of the pot to the middle contact/red wire. Such a simple problem that makes your $600 rotor system basically worthless! The wire contacts in the pot looked like new.
At first glance I didn't even realize the wire was supposed to be connected to anything, since the break was so clean.
Thanks to KD4APP for posting the a picture of his setup:
http://www.sunsunsun.net/kd4app/amsat/g5500.htm
and
http://www.sunsunsun.net/kd4app/images/g5500-pot.JPG
After I soldered the black wire, I put some electrical tape around the pot to give some strain relief to the wire.
It was amazingly clean inside, but North Carolina weather is pretty decent year round. Of course I cleaned/regreased the bearings (I should have used a bucket as suggested by Alan WA4SCA :) ) with some marine trailer bearing grease; it's thick and sticky enough to help hold them onto the races during reassembly. Only the "bottom" bearings showed any rust, and it was light. A rub with a rag and they were clean.
Hint for next time--do NOT stop the unit at 0 deg AZ before taking it apart. Rather, use 90 or 180 or 360 deg (since the unit does 450 deg, avoid 0 and 450). You'll want to avoid the "end stops" since the little lever gets in the way and won't let you put it back together quite right...
In the end, a satisfying repair.
73,
Mark L. Hammond [N8MH]