Modifying a Losmandy 492 Digital Drive Controller
Posted 30 September 2012 - 10:54 AM
Posted 30 September 2012 - 11:02 AM
Posted 01 October 2012 - 12:13 AM
Posted 01 October 2012 - 08:53 PM
Posted 01 October 2012 - 10:22 PM
I just happened today to install a set of Hurst stepper motors to my Schaefer mount (good timing!). Scott Losmandy had one of these motors that ran at 1/2 RPM when used with the 492 controller, so he sold me the set along with the 492 Digital drive. I'm not sure where he found the motor, but you might want to see if you can hunt one down that runs similarly. I'm guessing the motor has different gearing internally. If you need info on the model number or anything else, let me know.
Now, I ended up with a bit of a problem. Everything works fine except...... the RA motor is running in the wrong direction!
My mount has always had a single motor. When I'm standing in front of the mount (north side) looking at the mount, the motor is on the right side. OOC, which side of the mount is your motor on?
Posted 02 October 2012 - 12:01 AM
Posted 02 October 2012 - 12:38 PM
Posted 06 October 2012 - 06:01 PM
Posted 07 October 2012 - 12:54 PM
The only potential downside I see to the stepper motor conversion relates to "motor start delay." This would onlly be an issue for astrophotography, and then only if you're making a correction for declination drift. The Hurst AC synchronous motor start up is almost instantaneous. But, the stepper motor can take up to a full second to start, after you push the button. Two solutions: PERFECT polar alignment (no dec correction needed) or having a very high power guiding magnification that picks up a dec tracking error before it shows up on the CCD. I would be interested in your observations on that.
Posted 11 October 2012 - 06:48 PM
It also means that the slew rates in RA are much faster than they are in Dec. So, that taking a little bit of getting used to. Nonetheless, it sure beats centering objects at guide rates!