Synguide or Nexguide pushing star off screen

[AstroG]

Hello! This is my first post . I joined due to an annoying problem with my  celestron nexguide. I can find a star and lock it but when it comes to guiding it does an auto cal  and says m west ra+ on  tmr 23.0 dx-2 dy 11  moves the star in a given direction and then it says m west mov back . The problem is it then moves the star in the same direction until the star is pushed off the screen with the dreaded star lost message.  It says centre during the preview screen for ages  and polar align seems spot on . I set the guide speed through synscan to 0.5 . It's not a hot pixel as I can focus the star. I am using an eq5 pro mount with celestron 70mm travel scope. Any ideas ? I thought maybe there's a setting in the mount I'm missing.

[newbie alert]

It's calibrating.. and to stop those issues happening don't chose a star on the edge and increase the box size on your guidestar.. take it you're using phd2?

Edited September 8, 2021 by newbie alert
Corrected

[AstroG]

Hi there no it's not using phd2 - it's a standalone autoguider called celestron nexguide . It has a black and white screen like on the old Nokia phones and I placed the guide star dead centre. 

Edited September 8, 2021 by AstroG

[newbie alert]

Sorry I read it as nexstar...

Sorry I can't help but just typical of celestron products..

[dobblob]

I use the Nexguide very happily but only on my AVX with great results. 

The guider outputs ST 4 protocol. Are you sure the EQ 5 mount is compatible with this ?

[AstroG]

I had a quick look . The st4 port is on the motor control box  and accepts st4 input . I think the star may be too bright and its calibrating  in the wrong direction . It may also be faulty !

[dobblob]

Ah Ok ! You have both RA and DEC guide motors? Nexguide will not work on just RA alone.

Auto cal and auto lock automatically reduces the star brightness to an acceptable level by reducing the exp length. If it still remains too bright even at minimum exp I use a stop down mask.

I try fo find stars of mag 4 to 6, depending on guide scope aperture. The BRIghtness value can be anywhere between 25 and 250.  Are you using the 70 mm scope as a guide scope?

The guider for me in my configuration (so far!) in RA cal moves the star off to the left from center, no matter the orientation i.e left/right flip.  It can take say 15 secs to approach the screen edge and then moves back to center.

The DEC cal then commences to move from center to top for a maximum time of 30 secs or less if it detects good control. If good the guider switches automatically to guiding.

I use X1 for the guide speed. 

Since your cal only moves continuously in one direction you may want to check the 6 pin guide connector pins are clean and not bent. Try another cable if you have one.

The only problem I ever had with mine was a poorly seated connector which gave a similar fault. 

Good luck AstroG and welcome to the forum.

Feel free to ask more Qs.

[AstroG]

Thank you so much ! That was a lot of useful info and yes it's possible some of the connectors need cleaned . I can guide in phd2 so I sort of have an idea of what I'm doing.  Just for fun I actually put the synguider 2 firmware on it to ( the unit is the same one sold by both companies ) and it boots as synguider 2 version 1.2 now . No difference except the background is black and the stars I assume will be white . Hopefully the clouds go away tonight !

Edited September 8, 2021 by AstroG

[AstroG]

I think I've solved it ! I'm pretty sure my st4 pin layout doesn't match  doesn't match the pin out of the eq5 pro st4 port . Can anyone supply the st4 port wiring diagram ?

[Cornelius Varley]

It should match your image and this one. Celestron/Skywatcher both follow the same convention for the ST4 port.

[AstroG]

I managed to figure out the problem . Both ra+ and ra- move the scope in the same direction at 1 second forward in time ( basically I hear the ra motor stop as autoguide is set fo 1x) so it means either

1 the unit ( nexguide) is faulty or

2 ( more worryingly ) I have a fault in my autoguide socket on the mount 

 

No 2 causes a problem if I ever was to use eq mod  for pulse guiding . At the moment I'm using the serial port on the hand control for pulse guiding in phd2 .  

 

For anyone that's interested I used the location coordinates on the hand control the see the commands the guider was giving during calibration. 

 

Is there a way to check  the st4 port ? Is there a hand control that can be bought separately for it ?

 

Also if the mount's autoguide port  is set to 0.75 does that mean for ra+ and ra- commands ?

Edited September 11, 2021 by AstroG

[AstroG]

Solved !!!!!!!!!

 

This will also fix similar issues with phd2 st4 guiding errors such as no drift.

 

So it turns out bad firmware on the motor control unit was the issue.  You need an eq mod cable and the latest firmware from sky-watcher. 2.07 currently. Now the mount is working with the synguider !