Re: PSA- Check your gear mesh! (Older mounts)

Steven Panish

See my post from last night!  A loose DEC worm spur-gear lockscrew gives the same symptoms, except since the mesh is still good, you won't get any shaft wiggle.  Slow rates just take forever to turn the shaft enough to get rid of the play.  Guiding corrections will fail to do anything.  Just wish I hadn't ordered the y-cable.


On Sat, Aug 7, 2021 at 8:56 AM Chris White <chris.white@...> wrote:
The other night my guiding went haywire using my 900GTO.  It's worked flawlessly for several months so I initially thought I was having a software problem.  Essentially, after about 60 seconds of guiding dec would drift a little bit and despite PHD sending corrections, it would not respond.  To compound the issue, not only was DEC calibration failing in PHD, but also RA was requiring about 25 steps to clear the backlash. 

I spend a couple of hours debugging software, trying to see if APPC model correction could have impacted it.  I also changed PHD versions, and rebooted gear several times.  I checked my balance and fine tuned... I dialed in my PA (observatory mounted) but nothing seemed to work.

My last ditch was to see if there was a backlash issue, which in hindsight based on the behavior should have been my first check.  Sure enough, there was wiggle in DEC.  RA was solid.  The locking bolts for the motor/gearbox were gorilla tight, but following the AP PDF I remeshed in about 30 seconds and all of my problems were solved!  Gotta love this user friendly design to allow a quick and easy field adjustment.  In the PDF it explained that seasonally the mesh may need to be tweaked, so I assume that my wild Vermont temperature swings led to this. 

Well, now I know!  Of course, those of you who have mounts that automesh dont need to worry about this, but thought I would tell the story as there are a TON of older mounts out there that are faithfully performing like a champ!

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