Declination motion failure

Wednesday, May 4, 2022 5:06 AM

Problem(s) Encountered:

Telescope would not slew in declination.  This was not due to te typical issue of cycling the dec motor controller.


Noticed a red wire (+24Vdc IN) in the dec controller system that looked to be loosely connected in slot 5 of the bus by the dec motor controller in the doghouse at the base of the polar axis.  It slipped free the moment I touched it.  Curiously, I noticed that according to the schematics, this wire is listed as being in port 7, not 5.  While confused, I went ahead and attached it into port 7, as listed on the drawings.  This fixed the problem and the telescope is back in business.  The only idea I have is that this wire came loose and jumped perfectly over to port 5 yesterday morning.  This may have been due to the fact that this cable is routed through a similar path to part of the routing of the main network fiber.  Perhaps it was jostled just right to cause the one wire to move perfectly from port 7 to the neighboring port 5.  Sounds implausible but I’ve got no other ideas!
In the meantime, I also noticed another discrepancy between the wiring and the drawing.  A wire listed as ALARM COMMON is shown on the drawing to be in slot 38 on the same bus but in actuality is in slot 36.  Since things appear to be working normally, I hesitate to move the wire over a slot.  Instead, I’ve written to Dick Treffers to consult with him.  If he wants me to move the wire to 38 I will do so.  Until then, I just don’t want to mess with a system that appears to be working.