Fed up with the SynScan GOTO. Updated (Issue Solved)

[Geoff Lister]

I have the same Skyliner 250PX flextube Synscan GoTo. I bought it after enjoying the same GoTo system on my Skymax 127 Mak., but wanted more aperture. My experience is that the handset's indication of voltage is a few tenths of a volt lower than my DVM measurements at the power source. I usually use a 12V, 2.0A, plug-top mains PSU, with the 12V lead extended with about a metre of  heavy-duty, white, bell flex (shows up much better in the dark). I have measured supply currents for my powered mounts:-

The above are mean currents, and peaks will be slightly higher during acceleration. It is important to ensure that your 12V connectors are making good contact, and that any conductors have a decent diameter of copper.

At power-up, the "system" does not know where it is pointing, so it sets its electronic registers to zero (pointing to polar North and OTA level [alt = 0]). If the previous session ended with the "Park", "HOME" function, and the base has not moved, or has been put back exactly as before, then electronic and mechanical axes are aligned, and the handset should offer a reset from park position; avoiding the need for re-alignment (you still need to update time and date). Polar alignment is not required. The alignment process corrects for any errors in the starting position, and the cross-axis coupling if the base is not level, and the OTA is not sitting accurately in the Alt axis.

I have added a decent bubble level to the base, and use a wedge under one of the feet to get the base level. Turn the base so that the bubble points between 2 of the feet, and insert the wedge under the other one to centre the bubble. This ensures that the azimuth axis is as vertical as I can get it. This is not essential, but makes the alignment sums easier, and helps with the manual slew to the first alignment star.

I tend to use the "Brightest Star" alignment; often at dusk, when only the brightest stars are visible to the naked eye. Currently, I select Jupiter and, as the first slew is a manual one, the handset gives me the altitude, which I use to set the marker on the altitude scale, and then stand behind the OTA as it rotates, and stop when it is pointing roughly at Jupiter. Jupiter will then be in the finder, and I do the final centre with a 25mm EP and slew rate 4. Now the mount does a proper 2-star alignment, but with the advantage that it will do an automatic slew to the first star. Again, currently, Altair and Arcturus are visible from my garden, and make good alignment stars, clear of trees, fences and houses; and with good azimuth and altitude differences. I spent a few hours with the "Stellarium" program on my PC. I adjusted the date and dusk time for the middle of each month of the year, and selected 3, 4, or 5 bright stars, visible from my garden, and giving good azimuth and altitude separation. The table gives rough direction (N, NW, W etc.) and the altitude angle. I ended up with a table of 14 stars (+ Polaris, if stuck, makes a reasonable 2nd star), mostly the alphas of their respective constellations. I did the same for 1 hour before dawn, but this table has had little use.

I had to add a weight at the primary end of the OTA, as the clutch tended to slip if I was using a binoviewer, DSLR or my 2" 56mm EP. I also tightened, slightly, the altitude axis nut; but still leaving enough slack for manual adjustments.

Geoff

 

 

[Skywatcher130]

Some good advice there Geoff. There's a few tips that I think I will try with my little Skywatcher Go-to as it's not been as accurate as it has been previously. Think my power pack may need replacing too.  

[masjstovel]

8 hours ago, PlanetGazer said:

I use a lead acid battery which is 12V & 7Ah, I check the voltage before starting each session using the option on the handset. Currently it's 12.3 V. Below is a picture of the battery (I charge it by connecting it to the car's battery for a few minutes, engine running of course). Is the handset accurate in measuring the voltage? should I get a Voltmeter to accurately measure it?

 

 

The battery used is 7Ah, that should be more than what is required. I'm sure that I reset the park option, and have done a factory rest as well. and there is no polar scope on a dobsonian. it's an alt/azm mount.

 

Not at all, thanks for your help. Also there is no counterweights on Dobs.

I'm sorry, I didnt read Your post well enough, just got caught up in the power-supply-thingy:)

[Owmuchonomy]

It is highly likely the problem lies with your power supply. I had exactly the same problem with my 12 inch Synscan Dob. I solved the problem by using a 12V 4 amp mains power supply.  My Powertank was supposed to be 17 Ah but it would not power the Dob for more than 30 minutes.

[Marvin Jenkins]

I don’t use a dob so don’t flog me. However I have had strange alignment issues on big battery packs that claim max charge. If you can test your scope via a long mains cable plugged into your house supply it will indicate if you have a power issue. (Be aware of moisture dew)

You don’t need to do an observation session, but it might narrow down your problem and identify or eliminate a cause.

I lost three valuable nights astronomy due to major alignment inaccuracies. My large power supply said perfect but plugged into the mains all problems disappeared. A day later the battery said it needed charging! Eliminate the obvious.

Battery packs are great but the light systems on the front to test charge are not very accurate.

Marvin

[James]

A lead acid battery giving 11.7v is effectively dead for use with the scope. Connecting it to another battery (or any charger) for a few  minutes will result in the voltage going up, but it won’t last, check again in half an hour and it will probably be back down at 11.7. 
 

You really need to get a proper charger for it (I suspect you’ll need a new battery, lead acids don’t like being emptied all the way). If you use AC power then things will probably improve but if your are away from an easy source of power then you’ll need a new, fully charged battery

[Marvin Jenkins]

I agree with James. I use one of those jumper packs with a battery sealed inside as they conveniently have one or two cigarette sockets on the front.

They work great, but unless fully charged I have had problems. Mine has a button on the front, when pushed shows level of charge. It says green full, but it is not and needs a charge to be truthfully full.

[teoria_del_big_bang]

11 hours ago, James said:

A lead acid battery giving 11.7v is effectively dead for use with the scope. Connecting it to another battery (or any charger) for a few  minutes will result in the voltage going up, but it won’t last, check again in half an hour and it will probably be back down at 11.7. 
 

You really need to get a proper charger for it (I suspect you’ll need a new battery, lead acids don’t like being emptied all the way). If you use AC power then things will probably improve but if your are away from an easy source of power then you’ll need a new, fully charged battery

@James is spot on. The battery is not charged. 

I thought when fully charged but off load these batteries should be nearly 13.8V ?

It is okay saying the mount only requires 12V but essentially it is current it needs at or around 12V to operate correctly and I suspect a lead acid battery that measures even 12V without load will struggle to provide the 2A slewing current, and if you put a voltmeter on when slewing I think you will see the voltage drop well down below 12V.

You could be lucky and a proper charge from a proper charger may give the battery some life but if it has continuously been drained then only a short top up from a car then it my well be beyond being useful.

As above I would get a new battery and charger and make sure it is always fully charged before a session, do not fully discharge and recharge after every session. I would also be tempted to get a bit bigger capacity battery then 7Ah.

Steve

Edited September 30, 2019 by teoria_del_big_bang

[teoria_del_big_bang]

I would also add that the power issue may not be the only issue. You may have more than one issue (I really hope not), so do not despair if everything does not magically work 100% even after buying a new battery and charger, Hopefully it does but if there is more than one issue you have to address each in turn and put those right. And a good power source is the first thing that looks an issue so address that then see how it goes.

Whilst power for me was not an issue I had plenty and it can get disheartening especially when you identify some issue, spend money correcting it and then something else goes wrong.  But keep at it when it all comes together you will be so glad you did.

Steve

[Ships and Stars]

I use a Yuasa 70Ah deep cycle leisure/marine battery and fully charge it before each use. Heavy, but lots and lots of reserve power. £62. Both this battery and my 105Ah deep cycle in my camper read between 12.7 and 12.8V when fully charged, quickly dropping to 12.4-6 once in use and peaking around 13.8-14V when charging. I have a double cig lighter cable for my GOTO. Sometime I'll pop in the voltmeter and see what it drops to when slewing on Rate 9 etc. 

Edited September 30, 2019 by Ships and Stars
add pic

[JOC]

I have been where the OP is with mine and understand the frustration.  I have a 17 Ah Car jumpstart box that seems to work well, but for the avoidance of doubt it is also possible to invest in a mains plug for the system at reasonable cost.  Even it means running an extension lead testing the telescope with a mains supply in the back yard it would remove doubt in the power supply until the issue is solved.  I find the mains lead is a really good investment and only use my power box if I'm too far from the house for the extension lead.

FWIW I have never dismantled my Dob and removed said plastic ring and I've never adjusted the clutches - I wouldn't know what these are or what to do with them - I think with synscan Dobs they are a non-issue and in this case, probably, a red-herring.  What I have taken to doing is in terms of finding North I've started finding the Pole star and lowering the telescope to horizontal at that position and using that as North - at that point I switch on the synscan.

It might be worth checking the daylight savings time settings.  If you have a mobile downloading an application called Synscan init 2.0 and turning on the phone GPS will give the OP every setting correct and in the correct format that they need to put into the device, one thing I tripped over was don't forget to add in any leading zeros esp. in the position settings those leading zeros are really important if they are there - it does sound like you are in the East, but if you are in the west then a minus sign might be needed.  If you use the app. then enter everything exactly as it is presented - from what the OP writes it sounds like they are getting most things right, but the app. just give that extra confidence and I still use it each time.

Other things I found was that mine was highly sensitive to weight.  I don't know what the OP is using, but when you do the set-up try it with EXACTLY what the scope was sent with and nothing else.  No added finders, no big chunky EP's, no dew shields or heaters, no hefty battery packs etc.  Strip it down to just what it was sent with  and just use the little light Plossl EP's that probably came with the scope and the provided finder - nothing else - mine still calibrates best when I use only these with the telescope.   Also, don't fill the holders up with stuff or sit things on the edge of the base - do nothing to upset the balance or twisting motion and see if that helps.   It can also help if you use something like the mobile phone version of Stellarium to make sure you know which star the unit is driving to so that when it says centre star in the eyepiece you are certain in your own mind of which one to be getting into the middle of the EP.  I don't know my stars well and it does help to be certain you know where the scope is driving to and therefore what to centre on when it stops as part of the calibration.  It is also best if you select stars that are a longer distance apart in the sky so try to pick one that is almost behind you from North maybe. 

Also check that the cables are not getting wound around the scope as these can upset things.  Oh, yes and I can practically guarantee that the day you finally get it functional you will get that excited that you will forget the cables and after 10 minutes they will get that tied up that they pull themselves out and you have to start all over again!!

 

[Geoff Lister]

2 hours ago, JOC said:

Oh, yes and I can practically guarantee that the day you finally get it functional you will get that excited that you will forget the cables and after 10 minutes they will get that tied up that they pull themselves out and you have to start all over again!!

I loop the cable through one of the side handles. If the cable gets tight, the cable pulls on the shoe box, holding my plug-top supply & mains extension lead end; this slides on my patio quite well.

Geoff

[JOC]

2 minutes ago, Geoff Lister said:

I loop the cable through one of the side handles. If the cable gets tight, the cable pulls on the shoe box, holding my plug-top supply & mains extension lead end; this slides on my patio quite well.

That's actually not a bad idea.

[barkis]

You should check the  Battery voltage under the load condition.
And I agree that coupling your battery to another is not a suitable means of recharging it.
Get a proper charger, they are not very cost;y to buy.

A mains power supply with suitable AC voltage conversion and 13.8  DC output would
be more reliable, but of course the power supply would need careful protection from adverse weather.
Only the DC supply should reach your scopes electrical units., That cable too should be 
protected of course, you don't want to be tripping over it.

Extremely good balance of your telescope is a prime requirement too, although I'm
sure you don't need advice on that issue.   Hope you get it sorted soon.

These headaches can spoil the enjoyment no end.
Ron.

[Ceramus]

One simple thing that perhaps has been mentioned before but of great importance is the precise centering of alignment stars in the eyepiece. I use a high-ish power illuminated reticle eyepice and make sure the last adjustments are UP and RIGHT.

[PlanetGazer]

Update :

I would like to thank everyone for their contribution in this topic. I have finally managed to sort it out. As many have suggested, power was the issue, and I have managed to solve it. Sorry for the late reply, but finding the right time for an observing session + weather + debugging the issue, all contributed for the late reply.

 

I have planned to test 2 methods:

1- Use mains power 2- try car socket battery power. Which meant I had to find some power supply cable and an extinction cord for the cigarette socket to position the scope an appropriate distance away from the car, to keep all sides visible.

 

1- I found 2 power supplies with 2 Amp 12 V (Mains power),  tried them and both didn't align the scope correctly . I managed to find a power supply with 3 Amp 12 V and with multiple tries on different nights I finally managed to get the stars aligned with acceptable accuracy. As long as the target is anywhere in the 25mm EP view, I'm pleased. Boy was I happy when I managed to view Uranus for the first time! Not an easy target

 

2- So after I managed to align successfully using mains power, I had to insure that my scope works well when using batteries, since I ,mostly, stargaze outside my home. I tried using a working car battery via an interior cigarette socket, using the original cable that came with the scope, connected to an extension cord I bought. I manged to get an alignment that was one nudge away from target ( I might have been able to align more accurately if I tried again), though this was good enough for me to start the session and this time I went for Neptune! very small even in a 5mm EP, which was pushing the limit of my skies at that night. I have also enjoyed the views of a couple of DSOs.

 

My next mission now is finding the ideal battery for my use!

 

I would like to thank this community for helping me solve my problem and for keeping this hobby live and enjoyable!

 

 

Edited November 2, 2019 by PlanetGazer
Spelling

[banjaxed]

A 12volt 7ah like majstovel has should be more than enough for your needs, but you will definitely need a battery charger.

[PlanetGazer]

On 29/09/2019 at 17:20, Geoff Lister said:

I have the same Skyliner 250PX flextube Synscan GoTo. I bought it after enjoying the same GoTo system on my Skymax 127 Mak., but wanted more aperture. My experience is that the handset's indication of voltage is a few tenths of a volt lower than my DVM measurements at the power source. I usually use a 12V, 2.0A, plug-top mains PSU, with the 12V lead extended with about a metre of  heavy-duty, white, bell flex (shows up much better in the dark). I have measured supply currents for my powered mounts:-

The above are mean currents, and peaks will be slightly higher during acceleration. It is important to ensure that your 12V connectors are making good contact, and that any conductors have a decent diameter of copper.

At power-up, the "system" does not know where it is pointing, so it sets its electronic registers to zero (pointing to polar North and OTA level [alt = 0]). If the previous session ended with the "Park", "HOME" function, and the base has not moved, or has been put back exactly as before, then electronic and mechanical axes are aligned, and the handset should offer a reset from park position; avoiding the need for re-alignment (you still need to update time and date). Polar alignment is not required. The alignment process corrects for any errors in the starting position, and the cross-axis coupling if the base is not level, and the OTA is not sitting accurately in the Alt axis.

I have added a decent bubble level to the base, and use a wedge under one of the feet to get the base level. Turn the base so that the bubble points between 2 of the feet, and insert the wedge under the other one to centre the bubble. This ensures that the azimuth axis is as vertical as I can get it. This is not essential, but makes the alignment sums easier, and helps with the manual slew to the first alignment star.

I tend to use the "Brightest Star" alignment; often at dusk, when only the brightest stars are visible to the naked eye. Currently, I select Jupiter and, as the first slew is a manual one, the handset gives me the altitude, which I use to set the marker on the altitude scale, and then stand behind the OTA as it rotates, and stop when it is pointing roughly at Jupiter. Jupiter will then be in the finder, and I do the final centre with a 25mm EP and slew rate 4. Now the mount does a proper 2-star alignment, but with the advantage that it will do an automatic slew to the first star. Again, currently, Altair and Arcturus are visible from my garden, and make good alignment stars, clear of trees, fences and houses; and with good azimuth and altitude differences. I spent a few hours with the "Stellarium" program on my PC. I adjusted the date and dusk time for the middle of each month of the year, and selected 3, 4, or 5 bright stars, visible from my garden, and giving good azimuth and altitude separation. The table gives rough direction (N, NW, W etc.) and the altitude angle. I ended up with a table of 14 stars (+ Polaris, if stuck, makes a reasonable 2nd star), mostly the alphas of their respective constellations. I did the same for 1 hour before dawn, but this table has had little use.

I had to add a weight at the primary end of the OTA, as the clutch tended to slip if I was using a binoviewer, DSLR or my 2" 56mm EP. I also tightened, slightly, the altitude axis nut; but still leaving enough slack for manual adjustments.

Geoff

 

 

lots of good tips and advise in this post, which helped me. Thank you!

 

On 29/09/2019 at 21:19, masjstovel said:

I'm sorry, I didnt read Your post well enough, just got caught up in the power-supply-thingy:)

No problems at all

 

On 29/09/2019 at 21:49, Owmuchonomy said:

It is highly likely the problem lies with your power supply. I had exactly the same problem with my 12 inch Synscan Dob. I solved the problem by using a 12V 4 amp mains power supply.  My Powertank was supposed to be 17 Ah but it would not power the Dob for more than 30 minutes.

3 Amps for mains power seems fine so far,  4 Amps could be next on my list, though mobile batteries are my priority now

 

On 29/09/2019 at 22:08, Marvin Jenkins said:

I lost three valuable nights astronomy due to major alignment inaccuracies. My large power supply said perfect but plugged into the mains all problems disappeared. A day later the battery said it needed charging! Eliminate the obvious.

Battery packs are great but the light systems on the front to test charge are not very accurate.

Marvin

Trust me I have lost more, and kept my patience in many xD but glad that I gained knowledge in a new area (power and electricity)

 

On 29/09/2019 at 22:11, James said:

A lead acid battery giving 11.7v is effectively dead for use with the scope. Connecting it to another battery (or any charger) for a few  minutes will result in the voltage going up, but it won’t last, check again in half an hour and it will probably be back down at 11.7. 
 

You really need to get a proper charger for it (I suspect you’ll need a new battery, lead acids don’t like being emptied all the way). If you use AC power then things will probably improve but if your are away from an easy source of power then you’ll need a new, fully charged battery

This was also helpful, I've never went back to the battery and decided to try a working car battery first, before buying a dedicated one. Thank you!

 

On 29/09/2019 at 22:40, teoria_del_big_bang said:

 

As above I would get a new battery and charger and make sure it is always fully charged before a session, do not fully discharge and recharge after every session. I would also be tempted to get a bit bigger capacity battery then 7Ah.

Steve

I'm considering a 17 Ah or larger. Can't find a shop that will ship to me, due to safety regulations. Though I may just end up buying a separate car battery

 

On 30/09/2019 at 17:12, Ships and Stars said:

I use a Yuasa 70Ah deep cycle leisure/marine battery and fully charge it before each use. Heavy, but lots and lots of reserve power. £62. Both this battery and my 105Ah deep cycle in my camper read between 12.7 and 12.8V when fully charged, quickly dropping to 12.4-6 once in use and peaking around 13.8-14V when charging. I have a double cig lighter cable for my GOTO. Sometime I'll pop in the voltmeter and see what it drops to when slewing on Rate 9 etc. 

Impressive battery!

I've bought a value voltmeter for the long run. I will start to learn how to use it.

On 01/10/2019 at 10:59, JOC said:

I have been where the OP is with mine and understand the frustration.  I have a 17 Ah Car jumpstart box that seems to work well, but for the avoidance of doubt it is also possible to invest in a mains plug for the system at reasonable cost.  Even it means running an extension lead testing the telescope with a mains supply in the back yard it would remove doubt in the power supply until the issue is solved.  I find the mains lead is a really good investment and only use my power box if I'm too far from the house for the extension lead.

FWIW I have never dismantled my Dob and removed said plastic ring and I've never adjusted the clutches - I wouldn't know what these are or what to do with them - I think with synscan Dobs they are a non-issue and in this case, probably, a red-herring.  What I have taken to doing is in terms of finding North I've started finding the Pole star and lowering the telescope to horizontal at that position and using that as North - at that point I switch on the synscan.

It might be worth checking the daylight savings time settings.  If you have a mobile downloading an application called Synscan init 2.0 and turning on the phone GPS will give the OP every setting correct and in the correct format that they need to put into the device, one thing I tripped over was don't forget to add in any leading zeros esp. in the position settings those leading zeros are really important if they are there - it does sound like you are in the East, but if you are in the west then a minus sign might be needed.  If you use the app. then enter everything exactly as it is presented - from what the OP writes it sounds like they are getting most things right, but the app. just give that extra confidence and I still use it each time.

Other things I found was that mine was highly sensitive to weight.  I don't know what the OP is using, but when you do the set-up try it with EXACTLY what the scope was sent with and nothing else.  No added finders, no big chunky EP's, no dew shields or heaters, no hefty battery packs etc.  Strip it down to just what it was sent with  and just use the little light Plossl EP's that probably came with the scope and the provided finder - nothing else - mine still calibrates best when I use only these with the telescope.   Also, don't fill the holders up with stuff or sit things on the edge of the base - do nothing to upset the balance or twisting motion and see if that helps.   It can also help if you use something like the mobile phone version of Stellarium to make sure you know which star the unit is driving to so that when it says centre star in the eyepiece you are certain in your own mind of which one to be getting into the middle of the EP.  I don't know my stars well and it does help to be certain you know where the scope is driving to and therefore what to centre on when it stops as part of the calibration.  It is also best if you select stars that are a longer distance apart in the sky so try to pick one that is almost behind you from North maybe. 

Also check that the cables are not getting wound around the scope as these can upset things.  Oh, yes and I can practically guarantee that the day you finally get it functional you will get that excited that you will forget the cables and after 10 minutes they will get that tied up that they pull themselves out and you have to start all over again!!

 

I have used the default accessories for the initial trials until I got it aligned and then used different accessories but were similar weight and did not find any major problems.  regarding set up options, all were correct, I double checked with the amazing Synscan init 2.0 app as well.

 

and yes I was excited!  I found that the scope takes the longer angle to rotate sometimes, and the the cables get extended to the limit. to remedy that, I locate the object on the sky map, manually rotate the scope to the direction of the object  (with the handset directional buttons) then use the GoTo to locate the object, this will make the scope not turn more than 180 degrees and will contribute to saving power.

 

On 01/10/2019 at 14:22, barkis said:

These headaches can spoil the enjoyment no end.
Ron.

They have, but I'm much happier now xD Thanks for the help Ron

 

On 01/10/2019 at 18:09, Ceramus said:

One simple thing that perhaps has been mentioned before but of great importance is the precise centering of alignment stars in the eyepiece. I use a high-ish power illuminated reticle eyepice and make sure the last adjustments are UP and RIGHT.

 

This is good advise. the use of up and right as final steps to align, do contribute to the accuracy of the allignment