Mr Frodo 57

My setup is a Skywatcher explorer 200p on a HEQ5 Pro.  The mount is connected to the Rpi via a Lynx astro, usb to serial cable.  The Rpi is running Stellarmate used in wireless hotspot mode.  The laptop is running W10 and connects wirelessly to the Stellarmate hotspot.

Using the handcontroller and the mount slews smoothly in both Dec and RA with no issues.  

So taking up the alternative I will reflash the sd card containing Stellarmate to see if that makes any difference.

19 hours ago, malc-c said:

Sounds like a result then

What value cap did you use as a replacement and did you replace both as advised ?

470uf and 40v any bigger and they would have rubbed against the Dec axis and yes I replaced both.  Checked all the soldering with a magnifier and no dry joints or anything else so all good there.

But no result 😞

Tonight when testing under load I had the same problem again, the mount and 'scope (Skywatcher explorer 200p) are both balanced.  There were two random slews and plenty of loss of tracking due to the horizon limit being exceeded even though the 'scope didn't move in the slightest.  

The set up was full rig with control by Stellarmate on a Raspberry pi 3B with manufacturer's PSU, via wifi to my laptop 2 feet away.  The video clip of the laptop screen shows what is happening.  

Something appears to be upsetting the data so that the Rpi thinks it's had an instruction to go below the horizon limit and so cuts off tracking but as I say the 'scope does not move.

I have alternative systems Stellarium and Sky safari 6 and I will be testing with them to see what happens.

So scratching my head at the moment on this one.

On 12/03/2022 at 11:28, Mr Frodo 57 said:

Thanks for the encouragement I've managed to source a couple of new caps so will be fitting them when they arrive.

I know what you mean here as there are about dozen wifi connections listed in my immediate area.

I'll report back once I've soldered in the caps, observing the polarity as you rightly say Malcolm.

 

 

Ok so to report back.  Installed the caps and tested the mount indoors and it tracked on Stellarmate for an hour before Kstars crashed.  Nice and steady no jitters nothing so the first clear night I get I will set up and load up with the scope etc and test it for real.  Tonight would have been suitable if I hadn't got work in the morning.

So it is possible this is the culprit.

14 hours ago, malc-c said:

I've also replaced the two capacitors on my HEQ5 board which is a straight forward task, however I would suggest using capacitors of the same uF value, but at a higher voltage rating such as 50v - 100v -

1 hour ago, Cosmic Geoff said:

Electrolytic capacitors do age and fail with swollen tops, so you should definitely replace the two capacitors as suggested above.

Thanks for the encouragement I've managed to source a couple of new caps so will be fitting them when they arrive.

31 minutes ago, malc-c said:

So much stuff use wi-fi that there is now a lot of competition for bandwidth. 

I know what you mean here as there are about dozen wifi connections listed in my immediate area.

I'll report back once I've soldered in the caps, observing the polarity as you rightly say Malcolm.

I’m looking for some advice regarding a possible motherboard failure.  In the photo of the board in my mount the capacitor circled doesn’t look too good; I believe it has failed. ☹️

I’m using the mount with a Raspberry pi 3B running Stellarmate.  The Pi is powered by the official Rpi power supply and the mount by a 12v power brick with sufficient power for the mount and the peripherals.  The mount carries my Skywatcher Explorer 200p and both scope and mount are well balanced.  

What is happening is the mount will slew easily enough to a target then it will track for a while quite happily, but after a period of time, which varies between a minute and several minutes the reticle on my laptop screen will jump E/W or N/S sometimes by several degrees all the while the mount goes on tracking.  Then a N/S jump will take the supposed position below the horizon and the mount will stop tracking. 

I have also had the mount spontaneously slew to a different position, or creep until the ‘scope is pointing to the ground or worse still, collides with the tripod legs.  On occasions it has also  been slow to respond.  Polar alignment via Stellarmate is near impossible as the software reports 'Mount aborted. Please restart the process and reduce the speed.'  If I ignore this I can sometimes get an alignment but not always and reducing the speed does not help.  The same thing happens when calibrating the auto-guider, making calibration, on times, impossible.

I’ve removed the R-pi and noted the mount also misbehaves when using the Synscan dongle linked to Skysafari.  I’ve not had it do a random slew in this configuration but I did not have the scope on the mount at the time.  All I saw was the reticle on Skysafari flashing on and off at random intervals.  I can leave the mount running with the handset and everything seems fine but the whole idea of using the Rpi was to stay warm whilst photographing the stars and using a robotic telescope on my back yard.

It appears the problems are worse when the mount is loaded.

I understand from my research the failed capacitor is a smoothing capacitor for the power supply to the board.  Is its failure likely to be responsible for odd signals being transmitted to the Rpi which then cause the behaviour in the third paragraph above.  Is this the likely source of the problem?  Would it be worth simply replacing the failed capacitor in the photo to see if that would help?  Or is the board completely Kaput?

Any thoughts and advice would be appreciated especially if you have done something like this yourself.

Update - Problem found and all being well solved.

The Raspberry Pi 3B+ does not have an RTC and so I had added one to maintain the time between sessions especially as WiFi in my backyard can be a bit iffy.  I suspected from comments made about timing of Meridian flips and also electrical noise in the system that it may be something to do with the loss of synchronisation between the RPi and the laptop caused by a glitch with the RTC.  Sure enough when I checked the RPi the date was four days old.  Whilst the RTC worked fine once reset it lost the data overnight.  So I removed it from the RPi and set the RPi to connect via my home hub rather than create a hotspot.  This updated the time and I was able to do a test tracking for 55 minutes without seeing any reference to the horizon limits file nor any reference to align points as the reticle was not moving randomly  any longer the only movement of the reticle on the screen was a 1 pixel twitch where the screen was updating.

I'm not saying this is the answer in all reported cases but if you use an RTC in your RPi it may be worth checking it out.    

I believe in failing the RTC module had created a lot of electrical noise and that is what has caused the PA problem amongst a number of others.  My solution with the PA problem was simply to ignore the reduce speed message and leave it set as it was, I eventually got a PA.  It was only after that I found the problem was with the RTC module. 

Hopefully this will help someone out there with the same problem

As we have good Stellarmate following on this forum I thought I'd try this query here first.  Has anyone had the above message when polar aligning with stellarmate?

I've been using Stellarmate for several years now and after the initial learning curve have found it to be a great piece of software especially when I can plate solve and put the object of interest right in the middle of the FOV.  There have always been the occasional gremlin but until recently I thought I'd tamed them.  Then after doing the Rowan astronomy upgrade they came back with a vengeance.   first the above message when polar aligning and then Stellarmate would stop tracking for no apparent reason it would also flick the reticle North and South or East and West for no apparent reason but as long as the tracking didn't stop this had no effect on the image.  It's not the Rowan upgrade let me say first and foremost as I disconnected the RPi I'm running stellarmate on and reverted to the handset with no issues whatsoever.  The RPi has been running off an adapter connected to a battery pack up until now but it is now running off the official power adapter as in some testing I have done that performed best of all.

I've seen discussions on the Stellarmate forum but there were no conclusions I could find, and more recent queries on this have not yet been answered.

So does anyone have any idea why polar alignment should fail in this way and why Stellarmate stops tracking randomly?

Thanks for any help offered.

On 15/09/2019 at 00:08, bingevader said:

There's a group in Usk, but I don't know anything more than that.

http://www.uskastronomicalsociety.org.uk

We meet on Thursdays.  Why not pop along details are in the web link above.