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Trouble with EQMOD Polar Align goes too far-FIXED

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#1 UKJim

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Posted 26 October 2013 - 05:04 AM

Tearing my hair out with this.

Have recently started using EQMOD / EQASCOM, but no success so far with PA or Gotos in the field. I have stripped back to basics to understand whats going wrong and test it in a calm considered manner!

I am having trouble using the semi-automated POLAR alignment function of EQMOD with my Synscan 3.35 EQ5 mount (this is a basic EQ5 with a Synscan EQ5 Upgrade kit, not HEQ5).

I am talking about just getting initial polarscope PA right - not Goto alignment, nor the Alignmaster style PA corrections following Goto alignments.

I am doing this indoors with just the bare mount setup, no scope.

I am using PCDIRECT cable (although I also have EQDIRECT cable, but I have tried both ways and still the same result).

I set scope to Park position, turn on, connect EQMOD.
I have ensured settings for geo, date/time, dst etc in both the handset and EQMOD are same (although this shouldn't matter in PCDIRECT mode).

I use gamepad to slew to Dec port open and polarscope polaris circle positioned at top, ie. 12 o'clock.

I click Set Polarscope Home button.

The EQMOD PA window on-screen clock shows me, for example, an HA position of 20:00 (or 8oclock as a 12hour clock face). [This concurs with the HA shown by separate Polar Scope Finder software utility which I have used many times for manual PA.]
I select 12oclock from the dropdown selector.

I click Goto Polaris button, and the scope slews anti-clockwise from 12oclock position.

BUT IT GOES TOO FAR!

It carries on past HA20:00 and stops about 60 degrees further on, with polaris circle about 6.30.
There is no clutch slippage. It is exactly repeatable each time, and returns to Polarscope Home or Park precisely.

I have also tried:-
Factory reset many times
Double-checking date/time settings a thousand times.
Clear PAE
Downgraded from 3.35 to 3.27.

I wonder if upgrading to 3.35 has changed something in firmware that downgrading to 3.27 does not revert? But I had upgraded to 3.35 before trying EQMOD so cannot confirm that it worked with 3.27 anyway.

I am suspicious of the settings for the mount:-

From the EQMOD site page http://eq-mod.source...requisites.html

EQ5+Synscan Upgrade:
RA Gear Teeth: 144
RA Gear Ratio: 704:1
Microsteps per RA revolution: 4505600
Microsteps per Worm revolution: 31288.89
Resolution (arcsecs): 0.287642
Microsteps: 32

EQMOD seems to read the mounts settings when it first connects to the mount and stores them in a mountparams.txt file in the C:\Documents and Settings\username\Application Data\EQMOD folder:-
0,10000:132865
1,10000:132865
0,10001:4505600
1,10001:4505600
0,10002:36765
1,10002:36765
0,10003:16
1,10003:16
0,10004:703
1,10004:11249
0,10005:703
1,10005:11249
0,10006:31288
1,10006:31288
0,10007:0
1,10007:0

These settings are controllable from the EQASCOM Toolbox Custom Mount settings where you can choose EQ6 and HEQ5 settings. I have tried these but it didn't seem to help.

However the original Synscan printed manual says my kit is 0.144 arcsecond resolution (or 9,024,000 steps/rev) with gear ratio 705:1.
I think the EQMOD pre-requisites page implies that 4505600 at 32 (coarse) microsteps is equivalent to 9024000 at 64 (fine) microsteps? i.e. 0.288 resolution as opposed to 0.144 resolution

Does anyone using a basic EQ5 mount with EQMOD have this problem?

Can anyone confirm they at least use EQMOD with an EQ5?

Certainly the EQMOD page suggests it should be fine with my mount.

My suspicions re the settings might be unfounded!

Rather confused, and would really appreciate any help with this.
Jim

#2 rmollise

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Posted 26 October 2013 - 06:57 AM

I don't know that it would have any effect, but I set a polar home position with the circle at the bottom. Anyhow, what will for sure cause this is time/date problems. Make sure EQMOD and your computer program agree on time/date/position. Triple check, don't assume.

#3 UKJim

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Posted 26 October 2013 - 08:44 AM

Thanks Rod,

Thankfully I've now taken EQMOD out of the equation.
It's NOT EQMOD

Must be at a more basic level with the mount/hand controller.

If I just use the hand controller to slew the scope in RA by 90 degrees (watching the physical RA dial), and I check the Show Position option on the hand controller screen, the Azimuth is registering as having moved by approx 67 degrees ONLY!!

This is the same in either direction. Moving the counterweight arm from vertical to horizontal shows a change of either + or - 67 degrees.

Interestly doing the same with DEC it registers exactly 90 degrees Altitude change.

#4 Phil Sherman

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Posted 26 October 2013 - 09:11 AM

I think you missed the first step of using EQMOD's polar alignment routine.

Before you set the home position in EQMOD, you need to set the little alignment circle to the position you select in the EQMOD polar alignment window. You can eyeball it but that's not very accurate. The most accurate way is to place Polaris on the crosshair in the center of the reticle then use the altitude adjustment to move Polaris to the top of the large circle. Rotate the mount on the RA axis until Polaris is centered in the small alignment circle.

Now when you click the "set polar home" button, the mount will be aligned with the software's assumed position of the mount.

You should have levelled the tripod before attaching the mount. Doing this decouples the azimuth and altitude adjustments. I found this worked very well with my Sirius mount, and still does with my Atlas.

Phil

#5 UKJim

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Posted 26 October 2013 - 09:58 AM

Thanks Phil,
Yes, I've been doing that out in the field.
I've spent ages going through polar alignment technique, before discovering its actually some sort of problem or behaviour with the mount (see my most recent post above).

And why RA only, not DEC?
The motors are running fine, no binding, or slippage.

I'm wondering if from power on, the Synscan actually requires not only PA, but a 2 or 3-star Goto alignment to accurately build its sky model, so that it can properly calculate the number of motor steps that relate to 90 degrees, before you can carry on to using it with other software such as CdC or EQMOD.

However I thought EQMOD takes direct control of driving the motors, hence its need to know the precise settings of the mounts motors, steps, RA gear and worm ratios, etc.

#6 rmollise

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Posted 26 October 2013 - 10:15 AM

How are your go-tos?

#7 jrcrilly

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Posted 26 October 2013 - 10:49 AM

If I just use the hand controller to slew the scope in RA by 90 degrees (watching the physical RA dial), and I check the Show Position option on the hand controller screen, the Azimuth is registering as having moved by approx 67 degrees ONLY!!

This is the same in either direction. Moving the counterweight arm from vertical to horizontal shows a change of either + or - 67 degrees.

Interestly doing the same with DEC it registers exactly 90 degrees Altitude change.


That does appear to indicate a problem IF the controller is, for some reason, improperly programmed to mislabel the RA and dec axes as az and el. Dunno why they would have made such a basic error, though. If it is truly indicating azimuth and elevation those numbers would make perfect sense.

#8 rmollise

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Posted 26 October 2013 - 11:00 AM

Oh, can I wouldn't worry too much about the Show Position indication.

#9 UKJim

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Posted 26 October 2013 - 11:19 AM

Arrrgh!
What an IDIOT I AM !!!!!

Right Ascension Motor Drive checked:-

!!! WRONG BLOODY COG !!!
!!! WRONG BLOODY COG !!!
!!! WRONG BLOODY COG !!!
!!! WRONG BLOODY COG !!!

Days – weeks wasted!
Thank you, thank you, thank you to someone on another blog!

I couldn’t understand why a 90 degree slew was showing as about 67 degrees in the Ax1/Ax2 display of Show Position.

Couple of months ago I did some re-adjustment to the Right Ascension worm gear tension.

When I put it back together I re-assembled incorrectly with the worm gear end cog pressing against the motor intermediate cog, not its side-kick!

Various reasons for not testing the scope directly after, meant I totally forgot about this possibility.

I was sure it had to be something simple, but not that **** simple.

Thanks guys for your help and suggestions.
Pheewwww!
I'm not going mad, I'm just a numskull!

Sorry EQMOD for casting aspertions on your good name.

How many times has this happened?

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