Nexstar 5 - OTA removal

[malc-c]

Guys, been out of the hobby for a while, long story, but the advantage of having an observatory means that on the odd night when the sky beckoned it wasn't really any hassle.  Anyway I digress.

The other day a mail was circulated with in our society that a local guy was giving up and had an old (circa 15 year) Nexstar5 goto scope that he wanted to go to a good home otherwise it was going to the tip.  The problem is that the scope (well the mount) has a fault in that the goto's either stop mid way the mount suffers from a runaway and won't stop moving until the power is pulled.  Well as I love messing about with electronics and didn't want the scope to go to land-fill contact the guy and was fortunate to be first in the queue and went over to collect it on Friday.  It was immaculate, no dust or marks on the optics, still with the original  box and shipping outer from David Hinds.  Simple tests resulted in two runaways, and on checking the firmware in the handset is the last but one release which according to most of my googling should have resolved the issue (although according to some sites it's not guaranteed).  This is my first experience with Celestron goto systems, and as the optics are in such a good order would like to use the OTA on the HEQ5 mount, however the OTA is not attached to the single fork mount via a dovetail.  The azimuth drive seems to connected directly to the tube with no real way of removing the OTA.  I don't want to start stripping the mount as I don't really know what may drop out, and lose any encoders or something, but that's the only apparent way in.

I'm also going to change the power plug connection as that seems to be a regular cause of over runs / failed runs, but would welcome any suggestions on ways to get the mount back into service

[Cosmic Geoff]

I had a runaway caused by bad power connection with my Nexstar 8SE when I acquired it.  I wanted to change the power plug/socket but it was easier said than done. Eventually I fettled the connector, widening the split pin a fraction with a sharp blade, and fitted a cable tie to hold the cable to one side. I have no idea how to get the OTA off if it isn't on a dovetail, short of unscrewing everything. In the smaller and newer SLT mounts, two identical motor/encoder/gearbox assemblies drive large spur gears.  I doubt very much if the software is the problem.