The following procedure was just tested and verified, on my G1000dxa.
This is probably more than you ever wanted to know--but it's worth
having in the archive.
PROCEDURE FOR ALIGNING A YAESU-MUSEN G1000DXA ROTOR
1) General: There are two physical relationships you're going to
work on, in this
process, the rotor and the indicator. The general process is to
verify that each turns
through 450 degrees, and then to align each of them to North.
The rotor's stops are CCW @ 180 degrees, and CW @ 270 degrees. You
can align
on any point away from those stops, but North is a handy reference.
This procedure is appropriate wherever you have opened and
disassembled the
rotor for repair, and in that process have created a mis-aligned
condition. In my case, I
burned out a motor. Others have experienced broken sending-pot
coupling gears. Either
situation requires disassembly to the point where you must realign.
Requirements: Notepad and pencil or pen, White-out, or
similar marking material.
Medium philips screwdriver. Small tweaker screwdriver. A convenient
jumper between rotor and control box.
(rather than wrestle with 200' of heavy duty cable, I made up a 1m
jumper for test work.)
Clear table space approximately 1 square meter. Paper towels.
Plastic gloves.
(you WILL get greasy)
It is strongly recommended that you keep detailed notes of each
change you make, as
you work through this process.
2) Before opening the rotor, verify that it will travel through 450
degrees. Start by CCW rotation,
until it stops. Note the meter indication at the stop point. If
the meter stops moving before the
rotor reaches end of CCW travel, note approximately how many degrees
rotation results.
On the top casting, in line with the center stiffening section,
locate the small calibration
pip, which is on the lower lip of the casting, near the bearings.
Mark this pip with whiteout.
Mark the lower case with whiteout at the same point. This is South.
Rotate CW until the end of rotation. Note the meter indication at
that stop point. If the meter
stops moving before the rotor reaches end of CW travel, not
approximately how many degrees
rotation results. This should be 450 +/-, with small variations due
to meter calibration. If it is not,
the rotor is mis-assembled.
This rotor is normally set up for South stop. Rotate CCW again,
this time until your whitened pip
faces AWAY from the previous position. This is North. Mark the
lower case with Whiteout, so you know
it's North. Turn off power.
3) Open the rotor, to gain access to the sending pot, as follows:
* remove control cable.
* Place rotor upside down, removing 4 screws. This frees the lower
bearing retaining ring.
* Holding the lower bearing ring firmly in place, place rotor right
side up.
* Carefully lower the lower bearing retaining ring to the table
surface.
* Hold the upper and lower housings firmly together, and flip the
rotor upside down again, now
Allowing it to rest on the upper casting. Rotate the housing
so
the North mark is facing away from you.
* Carefully life the lower housing out of the upper casting. The
bearings should stay in place, in the upper housing.
Flip the rotor over, so it sits on the bottom housing. The two
stop switches should be on the side nearest you,
the cable connector should be to your left, and the sensing pot
should be to the right side of the gear assembly.
4) Look in the upper housing, and verify that the stop-boss casting
is intact, and is located just inside the
alignment pip which you marked with whiteout.
5) Connect the cable to the rotor. Remove the two small screws
which hold the alignment pot bracket in place.
(black plastic frame, on my unit.) CAREFULLY maneuver the pot out
from the motor cables, and out of the
gear assembly.
6) Power up the rotor. Carefully rotate the white nylon gear which
drives the sense pot, such that the meter moves
CCW, until it reaches the maximum CCW travel, and stops. At that
point, the meter should indicate South. If it
does not, remove the meter bezel, pull the indicator off, and replace
it, pointing South.
7) Rotate the sense pot CW, carefully, until the indicator reaches
its maximum CW rotation. This should be at or near
270 degrees. If it is not, a control box adjustment is required.
At the rear of the controller, switch from 'operation' to 'adj'
by sliding the switch to the right. The first potentiometer is
labelled "full scale adjust". Tweak this until the meter reads
270 degrees.
8) The OVERLAP LED should be lit. Rotate CCW, noting when the
OVERLAP LED goes out. This should be at 180 degrees.
If not, go back to 180, and adjust the second potentiometer, labeled
"Overlap" until the light comes on at 180 degrees.
9) Rotate the sense pot gear until the meter points North. Turn
off power. Remove cable from rotor.
10) Reassemble rotor, taking care to align the North marks on upper
and lower cases, reversing the procedure in step 3.
11) Previous comments about being careful to hold bearing rings in
place while flipping the rotor still apply!
12) Once assembled, reconnect cable, and run rotor through its full
range of travel, to verify that the CCW stop is at 180,
and the CW stop is at 270, and the overlap indicator comes on between
CW180 and CW270.
13) On the back of the control box, switch from "adj." to "operation".
With some care, and a bit of luck, you won't have to search and
rescue missing bearings!
Jim/N2EA
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