[amsat-bb] Yaesu G-5500 Potentiometer replacement

Jim Jerzycke kq6ea at verizon.net
Sun Mar 15 03:47:46 UTC 2015

Here's a quick question for those that have had the azimuth rotor apart.....

Last year when I packed things up from Field Day, I left the antennas 
and cross-boom in my "Mini Portable Roof Mount" system. During the drive 
home, my son noticed the antennas were windmilling in azimuth.

When we got home and unloaded the set up, you could turn the azimuth 
rotor by hand. It still hits the stops, and I haven't tried to run it, 
but I'm wondering what shook loose during the ride home.

Yeah, me bad for not pulling the cross-boom out!

I haven't taken the azimuth rotor apart yet (I have 4 complete G-5400 
and G-5500 sets), so do you think I really busted something, or did a 
setscrew just come loose?

73, Jim  KQ6EA

PS....I'll be using my "regular" setup for Field Day this year as NI6BB 
onboard the Battleship Iowa.

On 03/14/2015 06:59 PM, Kevin Schuchmann wrote:
> 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.
> 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.
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