LX200 Classic - inside the base

Update 10/1/2005

PE and M57 image after clean and a fresh learn update cycle, end of saga for now

Update: 9/28/2005

Click here to see the PE graphs after cleaning the gearbox
Update: 9/24/2005

The following images were taken from my second excursion into the base of the lx200 classic.

It has been not quite three years since the last main RA gear cleaning. The scope, in the last 3 years, has started to exhibit the same small 'jumps' again. These jumps are non-periodic and random that cause the scope to move about 10-15 arc-seconds in the 'blink of an eye'.

While I had the base apart, I also went looking for the cause of two anomolies I have seen. The first is a large excursion while tracking.
Click here to see the PE graphs before cleaning the gearbox
This was periodic in nature and would repeat itself at the same place in the worm rotation. The second was a 'drift after beep'. The scope would drift for about 4 seconds after a slew to the east. This drift would occur -after- the scope had completed the goto and had tracked correctly for at least 4-8 seconds.

Materials used:

Round wooden toothpicks - used on gearbox and main gear
Dawn(tm) dishwashing liquid - used for degreasing main gear
Synthetic motor oil - used in gearbox
Lithium wheel bearing grease - held up well the last three years

Main gear greased, applying grease to worm. Use 9V battery to spin motor while applying grease center

Results: The large periodic motion excursion at same place in the worm rotation seems to be gone! I fired up the scope and watched the tracking of a star near the meridian, plainly visible was the overcorrection I had to apply previously. I erased and did a single training of PEC, at no place in the cycle did the excursion exceed the capabilites of the mount to compensate for it. This is a definite improvement, previously needed to start compensating at least two 'beeps' before the excursion in the past. I found nothing but caked on 'something' inside the gearbox.

I also notice the amp guage on the base now lights up one less bar than it ever has in the past, another improvement!

Update: 11/7/2002

It does seem the cleaning has gotten rid of the 'jumps'. Six hours of imaging since the cleaning and I have not seen a single 'jump' on any image.

My lx200 classic started to develop the 'jumps', small movements in RA
of 5-10 arcseconds sporadically over different parts of the sky. I classify a jump as anything that cause the scope to move fast enough that an image will show all objects doubled rather than any form of streak when using PEC and pray.
I searched various sites and articles/postings and wondered if it could be dirt,
or shavings, etc in the gear.

It had gotten worse (more jumps) when I compared my images from March to
September 2002. The scope is about a year old in September and has about
250-300 hours on it. The last time I had the base apart was last December
2001 for a mobo swap.

After polling the mapug list I did not get a definitive answer, but did get
the suggestion of 'clean it and let us know' from Doc G.
Well at that time I just let it be, and about a month later (Oct/2002) I
found some time (and courage) to open it up.
The first trick was slotting one of the allen screws holding the cover
plate on between the forks, totally rounded out from the factory
(I knew this before I started, had tried to remove a year ago).

Here are the images after the cleaning.

Shows base cone and main gear mounted to fork assembly

Shows milled sholder

Three mounting screws for the main gear

Shows the main bearing mounted in the base

Shows the small steel ball used in the hinge assembly

Visit Mapug's home page for all your Meade LX200 classic questions and more

Visit the BMAA (Bucks-Mont Astronomical Association) website