[amsat-bb] Re: G5400B rotor maintenance

Alan VE4YZ ve4yz at mts.net
Fri Sep 11 12:10:55 PDT 2009

First determine whether it is just a dirty or worn winding in the POT that
is causing needle flicker.  Run the rotator on the bench with an ohm meter
across A2 and A1, then A2 and A3 ( same numbering on the EL - see schematic
) while running full rotation.  Don't connect the 1,2, 3 terminals to the
controller.  If it is smooth and uniform 0-500 ohms there is nothing wrong
in the rotators except your noise problem.  I've found the AZ always noisier
than the EL.

Storing the AZ upside down ( or in fact mounting it up side down as I once
did in error ) is big trouble as water will run into the ball race and
probably rust a few of the ball bearings and compromise the grease.  They
can be replaced easily and new grease installed.  That was probably your
stuck rotator.  It is probably all you need to do to get the noise problem
resolved.  It should at least be inspected to see what damage was done by
storing upside down exposed to the elements as dirt will have been cared in
with the rain.

It is not too difficult to get inside and snoop around.  You can start my
just removing the inspection plate to see the condition of the internal POT.
My experience is that the EL rarely needs to be opened up as it doesn't do
much travelling - at most 180 degrees but I bet most folks don't flip their
EL and so all it does is go up and down 90 degrees most of its life with far
fewer jogs than the AZ.

Below is a link to a rebuild where I replaced many of the metric screws and
did a re-grease for our -40/+40C WX in EN19. The ball bearing were not
replaced as they were pristine. Make sure you have a place for metric
machine screws before you start to open up.  The Home Depots in Canada had
all the metric screws I needed.  For Canadians contemplating a rebuild, I
found Canadian Tire had the largest selection of metric screws followed by
Roma and then Home Depot.  Auto suppliers will also have them for the
"foreign" cars made in NA. 


Good luck... Alan

-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of w6zkh at comcast.net
Sent: September 11, 2009 12:47 PM
To: amsat-bb
Subject: [amsat-bb] G5400B rotor maintenance

I recently picked up a G5400B AZ-EL rotor unit, which had been down on
ground for sometime. I recall it had been stored upside down outdoors. When
I got it home and hooked it up in the shop, the Azmiuth rotor was stuck, but
some manual help, broke whatever was stuck loose and it started to operate,
even abit noisy. The Elevation rotor is nice and quiet and works fine. I
notice now, after being used for afew weeks, that the noise is getting more
pronounced and also the meter indicator flickers, so I suspect water
probably got into the unit. 

Who does repair work on these rotors? I dont dare try it myself, as I know I
would end up with extra parts at the end of the day, even working in a tub.
So, would appreciate any help in finding a business that repairs these Yaesu

John W6ZKH 

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