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R: G-5400B reassembly



Hi David VE3STI,

I have disassembled and greased many KR 400 ,KR 500 and KR 600 but
the alignement procedure for all this rotators should be similar to your
5400B

You have to dissamble everithing again and get only the gear box with the
motor in your hands.

The inside potentiometers for Az and El are linear 500 ohm wire wound pots.

Connect an ohmmeter between the cursor and one end of the pot and run the
motor until you read 250 ohm  from the cursor and  each end of the pot.

This means that now the cursor is positioned in the center or 250+250 ohm
apart.

Apply this procedure to both potentiometers for Az and El

The condition 250+250 ohm represents 360 degrees or 0 degrees or North
position for the Azimuth and 250+250 ohm condition represents 90 degrees
position for the Elevation.

Without running  anymore the motors riassemble again the gear box for the
Azimuth  in order to have the tab on the cover positioned 180 degrees in
between the Azimuth limit switches.

For the Elevation riassemble again the gear box in order to have the motor
tube aimed at 90 degrees elevation.

The position of 90 degrees elevation for the motor tube is represented by
the mechanical coincidence of the marks existing one mark over the tube and
the other one over the cast of the motor.

Before running the motors double check if  the 250+250 ohm condition is
again corresponding for 360 degrees or North for Azimuth and  90 degrees
for Elevation.

Calibrate the electrical alignement with the control box potentiometers.

Please note that the control box fine electrical alignement for the Azimuth
must be made in order to have the pointer going to North with the azimuth
potentiometer at  250+250 ohm position and going to 90 degrees elevation
with the elevation potentiometer at 250+250 ohm position as well.

Control box calibration with different procedure it make mistake in position
readings at different angles.

Its all and i hope it helps.

73" de

i8CVS Domenico

----- Original Message -----
From: David Beach <VE3STI@rac.ca>
To: <amsat-bb@AMSAT.Org>
Sent: Friday, November 28, 2003 2:30 AM
Subject: [amsat-bb] G-5400B reassembly


> Well, I was given a Yaesu 5400B rotator and I decided to grease it before
> sticking it back up in the air. Unfortunately, I (ahem) wasn't careful
> enough to note alignment when I disassembled it. I seem to have the
> Elevation rotator under control but I am having some trouble with the
> Azimuth unit.
>
> After cleaning and greasing the bearings, I reassembled it, making sure I
> got the little 'limit arm' inside to align with the tab on the cover. (A
> blind procedure.) However, when I go through the electrical alignment with
> the control box, I just can't get the meter to 'zero' properly in the full
> CCW position (even twiddling the 'zero' adjustment on the meter). I seem
to
> have lots of range with the full scale adjustment in the full CW position.
>
> The manual is very limited in its help - I don't think Yaesu expects hams
to
> be disassembling the rotator! There is only an 'exploded' parts diagram.
>
> SO, anybody out there have any suggestions or experience with one of
these?
> I do not wish to disassemble and reassemble it many times because the
grease
> is messy and the bearings always seem to escape under things!
>
> Thanks for any help.
>
> David Beach
> VE3STI
>
> PS: I see there are no limit switches on this unit. What happens if one
> really bangs the rotator hard (accidentally!) against the 'stops'? Does
the
> motor burn out? A fuse blow? I see a small ?thermal switch on the
schematic.
>
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> Not an AMSAT member? Join now to support the amateur satellite program!
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