[GeoffW1 (Geoff)]

Hi,

I sent the following to Skywatcher Tech Support. Comment would also be most welcome from you Synscan gurus out there.

"
Backlash in EQ5 with Synscan upgrade......


I have the above kit, and quite like it, with a few minor problems. It carries a Skywatcher ED100.

The Synscan unit is V3.25, and offers backlash compensation entry. However I am puzzled as to how to reliably assess the total backlash in the drive train of an axis. I have done a lot of searching on the Net but advice tends to be non-specific and even contradictory.

I found a maintenance resource, disassembled the Dec axis, and found the worm shaft housing screws were loose. Having fixed that I tried to reduce the backlash overall and found that it could be composed of:

- motor hysteresis
- motor pinion to reduction gear backlash
- reduction gear to axis worm drive gear backlash
- axis worm drive gear to worm ring gear backlash
- worm ring gear to support shaft clearance (this was a size-for-size fit, so good there..)
- locking lever tip slip

I was not surprised to find I could not eliminate all backlash (as assessed optically). My questions are, because the Synscan user manual gives no clue:

- what is a good procedure to derive a value for entering into the Synscan setup?

- when and how does this value take effect ?
ie is it a sort of preload, applied by firmware?

Thanks"