[amsat-bb] Yaesu G-5500 Potentiometer replacement

[Kevin Schuchmann]

For what it's worth,  I have a rotor that has been going for 14 years, 
the set screw issue was cured early on with a drop of blue Lock tight, 
this counts for both the pot drive gear and the motor drive which also 
has a small set screw that likes to back out and then the rotor runs 
forever or until the windings fry.
   I did lose a motor winding once due to a jam so after that I shoved a 
thermal switch down between the windings to cut power in a over heat 
situation, 4 lock to lock rotations and it will cutout, the motors that 
Yaesu used have a very short duty cycle.
   The Pot...  never have had one go really bad where I had to replace 
it but that #$%^ wire in the middle for the wiper can be vexing, the 
turning and flexing breaks it and then you get wild extremes or bad 
readings in one spot, replacing it with the most flexible wire you can 
winding it like a  loose coil and  putting a small drop of epoxy at each 
end to stop wire movement helps it last the longest (several years for 
me), never had a problem realigning the stops if you make good marks of 
where it was when you started or if possible you run it to zero before 
you begin.
    I have also found that quicksilver marine grease 2-4-c with ptfe 
works really well and is readily available for the gears and bearings.

YMMV
73 Kevin WA6FWF



On 3/12/2015 11:14 AM, Todd wrote:
> I recently bought a _very slightly_ (like new) used Yaesu G-5500 
> rotator and have had some issues with the indication system. During 
> rotation of the elevation rotor sometimes both indication meters would 
> sometimes fluctuate violently to full scale. Finally the elevation 
> indicator just stopped at 90 degrees and stayed there or went to zero 
> when hitting the zero stop microswitch. Anyway, if figured the 
> position potentiometer was the problem and opened up the unit and 
> _found the gear on the pot shaft was slipping due to the set screw not 
> holding_. Although, it would grab at some point during the rotation 
> cycle again and hence be out of sync now with the motor stop! This 
> grabbing again in the rotation cycle destroyed the pot. Got two (one 
> spare) replacement pots from Yaesu and installed and calibrated very 
> carefully I might add. Adjusted pot to display "0" degrees, installed 
> gear on pot shaft and rechecked indication to be be sure I still read 
> "0". Assembled motor gearing with boom tube so stop switch @ zero  
> just actuated. Installed other case half and checked ok and dead on 
> after standard manual cal.
> Anyway, just checked the azimuth operation and see that the indication 
> is off at 90 degrees by 10 degrees or so. Watching needle from zero 
> the needle delays in movement by a couple of seconds after motor 
> starts turning. I suspect another set screw slipping again. I will 
> investigate further. I'm getting closer to interfacing the LVB Tracker 
> now. Anyhow, after looking everywhere on this BB and internet for any 
> procedure to change these pots in either rotator I did find this 
> posting from a Yaesu Rep that gives a guide to a individual if he 
> decides to take on the task of changing out the azimuth pot. The Rep 
> advises him to sent the unit to him in California.