Friday, February 8, 2013

LXD-55 10 inch SNT rides again!

The 10 inch LXD-55.  The mighty 14 inch looms in the background under its cotton cover.
My old LXD-55 has been stored in the garage for a number of years, and they have not been kind to the scope. I'm putting it back into service as the 14 inch scope is moving to the new dark sky site son and I want a scope I can roll out of the garage on nights when a trip out to the observatory is impractical.

The first step was to remove and clean the corrector plate, which was much less challenging and scary than I had been led to believe (if you mark the scope and the plate for orientation, it's fairly easy).  I also made a wooden "wheelie" to make it easy to roll in and out of the garage.  This little platform was made from 2 x 4s and is essential to avoiding the long and rather difficult setup if I had to pull out the scope components separately (which I would otherwise have to do as the darn thing is so heavy).

There were three big challenges.  The cold had cracked the autostar hand controller case and the plastic cowl covering the declination motor had cracked and fallen loose, damaging the encoder disk for the motor. In addition, the plastic spreader on the tripod had also cracked and broken.  As you can see in the image, I made a replacement spreader from plywood and it seems to work pretty well.  As to the encoder, I removed the disk and straightened it as best I could.  I plugged in the scope and powered it up.  So far, so good.  But as I was checking it out, it began wild and uncontrolled slews on both axes. Powering down, resets, and new cables did not solve the problem.  I took the autostar into the house and opened it an cleaned all contacts.  I then updated it to the latest version.  I tried the updated unit on my ETX 125, but the random slews continued.  I completely reset the unit and the problem seemed to be solved.  I then plugges the autostar into the LXD-55.  It started slewing again. I reset the autostar, and it seems the problem is solved.  I trained the scope without problems.  The next test will be how badly the crushed encoder disk compromises tracking and GOTO performance.  I'll post more as I do additional testing.

Finally, the screws that hold the counterweights in place fell apart when I tried to use them.  I had to drill out the sad remains from from the counterweights and replace them with standard screws.

Optically, the LXD-55 is an excellent scope for deep sky imaging.  But the Chinese-built mount is a disaster of cheap "engineering."  The scope is to heavy for the mount and the mount itself uses too much cheap, soft "pot metal."  I performed a semi-'hypertune" on it a couple of years back.  We'll see how well it has held up when the skies clear and I can use the scope.