HARA mount, vixen MD-5 driver problem
Posted 29 August 2013 - 10:33 PM
1. Bought a used C102 from Craigslist. The only identification on the CG-4 type mount is a very rubbed foil sticker that appears to say HARA under a line of Japanese (?) figures. The north leg has a star and the letter N stenciled. Any guesses on the identity?
2. The Circle V motor pulses but the shaft does not seem to turn. Pulsing speeds up appropriately with the 2x and 8x buttons. The mount is pretty rusty as if it sat exposed to the weather and the motor was attached - I removed it to check it out. There seems to be an area on the back of the motor, when I pull it from the plastic housing, that is discolored as if some water was there for a while. It does not come anywhere near the motor shaft, though. Before I screw things up :-) any suggestions on what to do or NOT do to try to salvage it? Lubricating, turning the shaft manually, take the cover off the front on the motor itself and move/adjust something? Seems as if there is a pulse it's not quite dead.
Not a major thing, the OTA and mount more than cover the cost, but the drive would be nice.
Posted 30 August 2013 - 10:12 AM
So, pictures please!
Posted 30 August 2013 - 02:06 PM
Posted 30 August 2013 - 03:09 PM
Is there somewhere handy I can go to see the differences and types of EQ mounts, eg. CG vs Polaris vs. Other GEMs, design characteristics and philosophies, tendencies, etc? I do see now that my Celestron, the 1960sd Japanese EQ on my Jason, and this mount take pretty different approaches. Heck, this one has four adjustments for movement on three axes, plus the adjustability of the tripod.
Posted 30 August 2013 - 04:25 PM
I'm not seeing the pics, but here goes anyways:
1) I'm guessing that you have managed to pick up an old-school Vixen Polaris, similar to the ones pictured here:
If so, congrats, these are nice little mounts, prized for grab & go observing with small telescopes (4" or smaller refractors and 6" or smaller Newtonians or catadioptrics). I'm currently on my second one (sold the first, then regretted it). Neither of mine said Vixen anywhere on them. So, HARA is not the brand
H.A.= hour angle
R.A. = right ascension
This is the label on the RA setting circle.
2) As for the motor problem, I would suggest removing the motor and seeing if you can turn the shaft it was attached to by hand (this rotates the RA worm). If not, you might need to loosen up the mesh between the worm and wheel. (There are 2 allen screws and one slotted set screw on this shaft, too tight, and it won't turn at all, too loose and there's noticeable backlash/slop in RA.) If adjusting the worm doesn't help, you may need to disassemble the RA gear assembly, clean the old grease off, then relube with a good white lithium grease or similar.
While it is dismounted, fire up the motor see if the output shaft rotates at all without any load (it will be very slow, ~1/10 rpm, the 8x setting may make it a little more visible).
If the motor turns and the RA worm turns, then it's likely a loose/missing set screw on the shaft coupler.
If the motor doesn't turn (but makes noise), most likely culprit would be a set of reduction gears inside the motor housing. Lube (WD-40?) might help stuck gears, but if the teeth are stripped teeth, you will need some luck and/or $$ to find a (used) Vixen replacement motor. There are some other options that work on this mount (see the thread above). Or just take the motor off entirely and use this with the manual slo-mo controls. (Don't try to use the manual slo-mos with the motor coupled rigidly to the shaft...this can damage the motor and/or reduction gears!)
I hope this info helps.
Posted 30 August 2013 - 06:08 PM
Removed motor from the shaft, shaft turns fine. Motor can be heard if held up to my hearing aid, turned all the way up <G> Gearbox turns freely from the shaft end when removed from the motor. Sprayed a little penetrating oil on the motor shaft, replaced the gearbox, and left it plugged in. After an hour or so I disassembled it again and the motor shaft rattled around. 5-10 minutes of gentle persuasion from my fingers and it moved pretty consistently. Is there another gear train in the motor can? Doesn't look like it? At any rate it, s louder now, audible at arms length. Is it safe to leave plugged in for hours? Gets warm but nor really hot.
I've not cleaned the black lube out of the gearbox assembly. It seems more like a light grease, should lithiun work?
Posted 31 August 2013 - 08:34 AM