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SALVAGING DEAD CELESTRON GT MOUNT

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#1 oddog

oddog

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Posted 04 December 2012 - 05:56 PM

A suggestion for utilizing an electronically dead Celestron GT mount as a manual AZ mount.

We recently bought three Celestron 102GT sets from a liquidation warehouse. All the OTA’s were excellent achromats but two of the mounts didn’t work. Turned out the main PC boards were bad so we gutted the mounts (selling off the motors and connectors) and use them as manual push-around AZ mounts.

Both axis’ have a nylok nut on them to act on a clutch mechanism which can be adjusted to your liking. Removing the motors probably makes everything work more smoothly but we didn’t try it manually with the motors in. For declination this does require removing the side cover of the arm (two screws) or do what we did and drill a 1/2" hole on the side of the side cover and have a long socket on a wrench in your kit (small knob driver) to adjust as needed. Of course you have the option of moving the OTA/dovetail a bit back and forth in the Vixen saddle for proper balancing before you adjust the clutch nut. The clutch adjustment in the horizontal/RA axis is the same but you have to remove the mount from the tripod (large hand driven retaining bolt on the bottom, takes a few seconds) and you will need an open end wrench but it doesn't normally need adjustment once a friction level is set as there is no balancing in that axis. We have an Orion 102ST attached to ours for quick views and the setup works great.

The GT mount uses the standard Vixen dovetail so it easy to use small scopes with Vixen dovetails (like many 4"/5" SCT/MAKs, and short tube wide field refractors). Shape and overhang of the mount allows getting to zenith depending on the rear overhang of your scope. If you don't have a Vixen dovetail on your OTA (but do have a 1/4-20 tripod socket) you can get an "L" bracket from Orion for $30 (item #05052, http://www.telescope...Orion-Doveta... ).

These mounts are often found at flea markets and thrift stores as they were mostly sold to newbies that couldn’t maintain their interest or the units failed.

One caveat regarding this mount is the tripod often found with it. If it is not the round tube version you might want to pass as that tripod is, frankly, awful. The later round-tube version is much better and very competent.

Tom Duncan

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#2 Jon Isaacs

Jon Isaacs

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Posted 05 December 2012 - 07:58 AM

:goodjob:

I had a Celestron 130 SLT and the electronics gave up the ghost. I removed some of the electronics and turned it into a alt-az mount. It had the 1.25 inch stainless steel tubular legs but they still were not adequate support so I replaced the legs with some from a Vixen Portamount and that resulted in a solid mount...

Jon

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