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DEC is lagging on CG-4

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#1 Holydiver

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Posted 26 January 2013 - 12:51 AM

So I bought an Orion Mini 50mm so I can increase my exposure limit of 30 seconds with my CG-4 and I've noticed that my DEC lags a bit, I've ruled out my Synscan GOTO motor as the culprit.
If I move the DEC up, then go to move it down, it lags for about 5 seconds before it begins to go down, same if I move it down, it lags before it begins to go up.
The length of the lag correlates with the hand controller speed, so if I use move the DEC really fast speed it isn't noticeable, but if I try to move it at the tracking speed it takes about a minute to catch up.
So PHD can't calibrate DEC because it lags for about a minute before it actually begins to move.
Any ideas?

I suspect (but I may be wrong) that it is the connection between these two parts here:
http://imgur.com/WBtmbZX

#2 rmollise

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Posted 26 January 2013 - 08:31 AM

This is backlash. On these mounts you will pretty much have to live it it. It's generally not much of a problem if it's not too bad. Five seconds is a bit much, and it's possible you might be able to reduce it by tightening the gears a bit, but the usual solution is to increase the calibration steps in PHD. On ANY mount, this should be set to about 1500 - 2000 when using a 50mm guide scope. Good luck.

#3 Holydiver

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Posted 01 February 2013 - 12:57 AM

I've discovered that I can remove the minute+ DEC backlash I get by setting the backlash to 0°20'00 in my synscan hand controller.

Problem is, when the scope is connected to EQMOD and PHD, it disables the backlash settings in the hand controller.

There appear to be backlash settings in EQMOD but they don't seem to do much and they are in msec rather than degrees.

Is there any way I can translate the 0°20'00 DEC backlash settings on the hand controller into backlash settings that work in EQMOD and PHD?

If not, is there another 3rd party program that allows me to adjust for backlash?

#4 rmollise

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Posted 01 February 2013 - 09:28 AM

No. What you need to do is try setting the PHD Brain settings as I suggested. If that won't allow you to calibrate, the option is adjust the gears.






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