Telescope Reviews: Buying Celestron CG-5 Mount

[ See EDIT below ]
I upgraded my CG-5 HC and MC to the latest versions just yesterday, and all looks right. However after reading this thread, I tried PECTool, and it does NOT find any encoder index. BTW, I happen to have replaced the motor/encoder in mine with a new one from Celestron just a month or so ago, so I'm pretty sure it's not because they've changed the hardware.

I'm thinking without being able to find an index position PEC training would not be feasible.

So.. the confusion really is about how/why Bluegrass's CG-5 is different in that it finds the index????

al

***** EDIT - did more testing, got more results, changed my conclusion, and raised more questions:

I tried again, this time letting the motor run a long time, PECTool reported it found the index after the RA axis rotated almost 90 degrees. So, the system isn't simply finding a motor encoder mark with a few turns of the worm (like it does on my CGE). On every power up of the mount, searching for the index gave the same result (90 deg rotation in RA) and had no relation to the starting position of the RA axis or worm wheel. What I don't know is whether the worm actually gets set in an indexed position, or if it's just a fluke of the motor control circuitry, for example just counting turns from the power up position.

OK, so regardless, I tried some things with PECTool:

Downloading the PEC from the mount was initially a flat line. Then, I tried some fake training using the HC. On the first try it didn't work. On the 2nd, I did get a change to the graph, but the session aborted early (I'm thinking that training with the HC might be flakey).

-- I think this part is interesting:
Then I uploaded the modified PEC curve to the mount. It took it and I verified it by D/L it from the mount and it was the same. I disconnected and shutdown PECTool, and powered down the mount. Restarted the mount, restarted PECTool, then D/L the PEC curve from the mount. It was the modified curve. So! the PEC info is permanent. I didn't see a way to clear the PEC other than to retrain, so I did a factory reset of the HC. That restored the PEC curve to flat.

So, there is a buffer that retains PEC training and it's apparently permanent. Now IF the mount is actually finding and remembering a worm index, then PEC is possible. I'm thinking actual training and more testing will be needed to find out if the mount will actually use the PEC info and if playback has to be "started" with PECTool each power-up.

Interesting..... (what else to do on a very wet Saturday morning)

al

Edited by AlanT (10/17/09 03:28 PM)