Bill,

What kind of grease did you use?

Thanks

Bob

-----Original Message-----
Sent: Wednesday, October 17, 2001 8:20 PM
To: MAPUG
Subject: [M]: Meade Service Kit/Pointing Accuracy/Image Vibration


To all:
Some time back I wrote about image vibration caused by the tracking motors.
In the process of resolving that issue I contacted Meade and was provided
(under warranty since my scope was only 4 months old) with a service kit
consisting of a new mother board and new RA and Dec motors. Meade believed
the vibration was caused by defective electronics.

The image vibration problem was noticible only on Saturn and Jupiter and
looked exactly like poor seeing conditions. I detected the vibration by
turning off the tracking motors which stopped the vibration. The vibration
returned as soon as the motors were turned back on. As it turned out the
vibration was cured by simply removing the original Dec motor, the Dec
clutch and big gear then cleaning and regreasing everything and reinstalling
it carefully. The Dec motor is adjustable in relation to the big gear to a
certain extent because the holes in the motor mount have some play around
the mounting bolts. You can vary how close the worm gear is to the big gear
and you can vary the angle somewhat by tilting the motor up or down. In
addition the Dec motor can be shifted right or left. From the factory my
Dec motor was shifted right and tilted down. When I replaced it I shifted
the Dec motor left to clear the big gear as much as possible and made it
level and straight in relation to the big gear. The motor noise was greatly
reduced, the worm turned much smoother and the big gear no longer hit the
soft rubber tape over the rear of the Dec motor. The image vibration
disappeared and my Dec operation was substantially quieter and smoother
overall.

Given the extreme improvement in Dec performance I decided to service the RA
system as well. I had a tight spot in in RA which caused the pitch of the
motor to increase noticibly over about a 45 degree part of the rotation
because the motor had to work harder to turn the scope over that area. I
completely disassembled the RA assembly and gears. It is very easy and took
about 15 min following Mapug instructions and photos. I did not remove the
big RA bearing which was stuck on the RA base. There was no need to remove
it since it was clean, straight and turned very smoothly. Then I cleaned
the parts and regreased them. Reassembly is key. There was nothing major
wrong from the factory installation, no dirt or metal chips, just lack of
extreme care in aligning the various parts. First make sure you have grease
on the parts evenly. Assemble and disassemble everything 5 or 6 times for
practice til you get the feel for how the parts should work together. On
final assembly carefully center the parts of the main gear assembly and
slowly tighten bolts in a criss-cross pattern increasing the torque in
steps. When I had the parts back together there was absolutely no tight
spot. The entire assembly was now round and free of any binding.
Reinstalled the RA motor so that it was shifted left for maximum clearance
of the motor housing and the big gear and straight and level. RA motor
noise was now much quieter and consistent all around a 360 deg rotation.

Then the service kit arrived. Even though all of my problems were already
solved I decided to install the kit anyway. I replaced the main board the
the original RA and Dec motor; the job took about 15 minutes since by then I
was very familiar with the inside of the LX200. I was very careful to see
that both motors were properly aligned to thier respective gears. The
service kit worked fine on my workbench. On star testing I noted that the
RA motor behaved oddly. There was retro motion when I pressed the E or W
direction keys and the star image would jump up before it started to move
sideways. I called Meade and told them the new RA motor was wacky and asked
if I could replace it with the old one which had been working perfectly. I
felt I had to ask since the service kit was called a matched set consisting
of specific motors tested with a specific main board. My request was
approved after some consultation and I reinstalled the old RA motor which
worked perfectly. All retro motion and jumping were gone.

The good news is that my pointing accuracy was vastly improved by the
service kit or the Dec/RA service or some combination thereof. Before I
installed the service kit and did the Dec/RA cleaning and regreasing, I was
getting pretty consistent 2 arc minute pointing accuracy. After the service
kit, etc my accuracy more than doubled to under 1 arc minute. This is
without HPP. Some nights I now hit targets within 30 arc seconds or less.
It is amazing. Maybe some electronic sets are more accurate than others or
maybe the better adjusted RA and Dec drives allow the motors to work better
or maybe a little of both. I also use BestPair11 and a reticle EP and make
sure there is no backlash as I center the alignment stars. I have also made
the OTA orthogonal to the Dec axis.

Bottom line is Meade was very helpful and willing to assist me and the scope
certainly performs beyond the accuracy claims in Meade's adds which at one
time I questioned. Thus I take back anything bad I ever said about Meade
and compliment them on making a fine product at a fair price. I do still
believe that Meade should sell a complete shop manual with good photos,
drawings and instructions.

Regards

Bill Wood
LX200 10" f/10
Phoenix, AZ

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