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Paul,

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I saw very similar symptoms with my mount 3 times over last month. 20 nights, give or take.

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I do imaging with KStars/Ekos. The mount is connected to PC via Ethernet, HC is not connected at all. At some random point the mount stops talking to INDI driver. I do not see anything interesting the exact moment when it happens, seems pretty random. Meanwhile, the mount continues tracking until it hits mechanical resistance. Gemini Web server does not respond. Ethernet link is up as seen from the PC but no traffic there. When I see it happened, I come to the mount and plug HC. It lights up, goes to 'Connecting to Gemini' screen, waits there several seconds, and cycles back, again and again. Simple power cycling Gemini restores it back to a good state.

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This has never happened during the two years I have and very actively use the mount. It was L5 originally. I upgraded it to L6 as soon as the upgrade kit became available. I upgraded it further to 6.10 later with GFU. So far so good.

Until recently when bought second mount. Now please bear with me.

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That mount's Gemini bricked on second night. I contacted Losmandy and they sent me a replacement SD card. You may have heard this story from them. That new card helped resurrecting the Gemini and also likely updated the HC. Likely (I cannot say for sure but also do not see any alternative explanation) I then plugged that HC to the first mount for some quick task as I occasionally do. Nothing wrong at that point but next day the first mount bricked too! Losmandy sent me another SD card and it helped again. It happens to be 6.10 which should be the same version and I already had on that Gemini. The mount worked mostly fine since then. One suspicious thing started after that upgrade:

The power supply is 14.1V, not anywhere near 24V. I did not change it. The second mount sits on the same DC output and is connected in very similar manner. It reports 14.1-14.2V. Anyway, the mount has been working, so I ignored this quirk. Before the bricking and upgrade the first mount reported the voltage correctly.

Not long before I was forced to upgrade I saw the coin battery at ~2.8V. So I decided to change it too while I was there. I do not remember when exactly I changed it though. At first it was reported above 3V, but after several days it dropped to 2.9V, then 2.8V. That may be just a crappy battery or a symptom of something in Gemini, I don't know. Somewhere at that time I had the disconnect issue happened to me the first time.

I ignored the problem and continued using the mount for another several nights. Three days ago it happened again and had been waiting for me until last night.

As the coin battery was looking quite bad by then I decided to replace it again. I checked the old battery by shorting its outputs for 10s and measuring voltage after that. It was in the 2.95-3.0V range. The battery itself and Gemini contacts look clean, no rust or anything. Anyway, I put the new battery in, reset the settings, set time, loaded SRAM back.

I then immediately upgraded to 6.12 with GFU, cycled the power a few times. All looked good, so I started the imaging session.

In two hours it disconnected again! I simply restarted it because I have no more ideas what more I could jiggle. It worked fine through the rest of the night and is still online. The above screenshot it taken just now.

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I hope you fine some clue it this pile of details!

Hi Don,

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Check a few settings in Keil debugger:

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1. Goto Flash->Configure Flash Tools... menu. Click on Device tab. Check that the correct device is selected: NXP/LPC2388/ARM

2. Then, inside the same window click Target tab. Check that ARM Compiler is selected as Compiler Version 5.

3. Go to Debug tab. Near the top, the second radio button Use: ULINK2/ME ARM Debugger should be selected

4. Under the same Debug tab, click Settings... button next to the "Use:" selection in step 3.

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If your ULINK2 is connected to Gemini and Gemini is turned on, you should see the ULINK2 device name shown under JTAG Device Chain.

If it shows an error, you may not have a good connection. Check cable and pin alignment.

Try changing the max JTAG Clock on the same screen to 100KHz instead of 1MHz. Your goal is to see the ULINK2 device shown as connected. Then, you can proceed to Flash->Download

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I have an update on the instructions provided.

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I ordered the ULINK2 programmer and downloaded both software packages. ?Here is what I learned.

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1. ?Failed the first time as the Keil link 2 software didn't download the legacy packages for the processor used in the G2. ?I was able to download the package as suggested by Keil so that was resolved.

2. ?I received the could not load file error message when doing the Flash and Download selections from the menu bar. ?See attached photo.

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For reference I also ttached a photo of the ulink2 programmer attached with the G2 powered on.

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Please let me know what you think is the next step.

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Thank you.

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On Wed, Apr 9, 2025 at 12:27 PM, Paul Romero wrote:

hi guys,

It looks like the a new battery fixed.?

Clear Skies,

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Paul

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That's because the battery really needs to be replaced once a year to ensure reliability.? Don't go by the voltage display or the idea that the circuit should be able to maintain the memory correctly down to some lower voltage per the chip maker's data sheet.?

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The battery industry standard for a worn out / failed battery of this type is a 10% voltage drop unloaded from the as new voltage.? In the real world these batteries when fresh are 3.2 - 3.3V tops volts unloaded.? This means that as long as you replace the battery when it measures 2.9V out of circuit you will have a reliable system.? This is seen time and time again in Gemini and Losmandy groups but somehow it escapes almost everyone.??

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I put a piece of blue painter's tape on the back of my Gemini controllers and write the replacement date on it when I install a new battery. I also carry small tools and battery spares in the mount's hard case.? I no longer have these mysterious failures and bad behaviors.? Now my only Gemini issues seem to be caused by me.

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If it takes several days for this to happen, but doesn't happen within 24 hours, it sounds like you may have an issue with the real-time clock in Gemini. It's powered by a 3v battery internally, so that could be another source of problems. I would check how off the Gemini-reported? date and time is after a few days of Gemini being powered down.

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On Thu, Apr 10, 2025 at 11:20 AM, Joe Ulowetz wrote:

The diagram in my message may not have been clear about what is going on. Maybe this will help.

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This is the situation when I power up Gemini-2 after being off for several days.

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When I tell it to park CWD, this is what happens:

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After doing a cold start (usually requiring a power cycle as well), it fixes the problem. If I tell it to park at my Home location (due west ), it reports the correct location now.??

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Leaving Gemini-2 unpowered for one day, the problem doesn't happen. If I leave it unpowered for several days, that is when it starts up (after a Warm Restart) with the wrong location reported.? As I mentioned in my previous message, maybe the firmware update fixed something. I'm leaving it off for a few days right now to see what happens when I restart it next.

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On Wed, Apr 9, 2025 at 05:23 AM, Paul Kanevsky wrote:

Are these helpful in overcoming periodic error and for reducing the need for autoguiding on these mounts?

Well you asked things which I have not tested lately but long time ago and do not remember. I would need to test it again but honestly ?for what? The price of the mounts compared to other encoder equippedones is good.

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The tracking is very good I would say even so I do autoguide with maybe 1-2 second exposure time and inbetween a pause of 4-5 seconds.

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The big problem is the SDE error ( Sub-Divisional error) but this comes from bad programming.

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BTW I have number 1 and 2 from the production start and they had a lot of bugs which I reported during 2 years and iOptron gave me the nickname " Mr. Bug #1".

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I was the one who reported the most quantity of Bugs but then they left me standing in the rain with my rest problems, but OK, I can use them and SDE error comes up mainly over 1500mm focal length at high resolutions. At lower focal length you do not see it.

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I assume iOptron has solved this problem in the last 7 years. I got mine in April 2018. Mechanically those mounts are very good. Balancing is a piece of cake.

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I can track the Sun over 4 hours and it moves a negligible amount in RA. Of course the Sun moves in DEC all the year feom South to North and backwards.

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Here is the Sun tracking with the eclipse of 2024 at my place. I had Ha and White light scope on the same mount. I did not correct during the whole eclipse.

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Rainer

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Do you mean the check boxes on the hand controller to reverse movement direction?? I use those all the time, but they don't result in Gemini reporting coordinates on the opposite side of the sky from where the mount is pointing.

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FYI, I updated to the latest firmware recently.? After I did that, I had this problem happen once more, but then the next time I checked it didn't happen. My next chance at clear skies will be Friday when I'll check again. I'm hoping the firmware update may have fixed whatever was wrong.

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Thanks,

-Joe

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Check your Gemini 2 settings for reverse RA and DEC movement.?

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hi guys,

It looks like the a new battery fixed.?

Clear Skies,

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Paul

On Tue, Apr 8, 2025 at 05:47 PM, Rainer wrote:

Some more images, but the configuration has changed now. On the mount in the back is a Mewlon 250S 1st generation which I modified to ASCOM focuser using a slim 22mm? ? Faulhaber stepper motor with ZWO EAF electronics.

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On the mount on the front the two Solar setup were replaced by the ASKAR 103APO.

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I also attached an image of the encoder disc on the worm wheel. This is not from a CEM 120EC2 but from a CEM 60EC.

On Tue, Apr 8, 2025 at 02:49 PM, Rainer wrote:

On Tue, Apr 8, 2025 at 03:21 PM, Paul Kanevsky wrote:

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Very nice! But I think you need more weight on that mount to get it to full capacity ;)

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The mount with TOA and ASKAR has 42.6kg of counterweight

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I agree, the Askar optics seem to be pretty good,? overall people are getting good results.? This little Askar is an FRA500 is sharp at its native 500mm f/5.6 and a wonder at f/3.9.? Okay so it's no match for the modern Takahashi FC-100DF with a CAA and? FC-35 reducer but it was $1,200 used vs $4,500.? Askar is a good deal IMHO.? ??

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The most counterweight I had on the G11G counterweight shaft was 41kg.? In this photo I only had 37kg as the other 9.5kg weight was in use and I had to use the 5kg and move them down the shaft more.? It works fine but I think this is pushing it with 34kg + in a Losmandy Side-By-Side saddle mount.??

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For the last few years I've been using the ASIAIR and have not had any issues guiding with the same old piggybacked Stellarvue F050 50mm f/4 guidescope in the matching non-adjustable clamshell I've used for the last maybe 7-8 years.? It worked great with PHD2 and people claimed it wouldn't because I needed adjustable rings and I was doing about a zillion other things wrong which were absolutely incorrect.? The one thing I know is true and has remained true since way back when I first started using PHD2 is that the relationship between the imaging scope's image scale and the guide scope's image scale is critical.? That ratio has changed over the years as PHD2 has improved tremendously with the addition of multi-star guiding, CMOS cameras taking over and the CMOS sensor photosites somehow managing get more sensitive with lower noise and somehow also getting even smaller, it's a win win IME.??

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All of these things have been making it easier to get better autoguiding with modern CMOS cameras.? Back in the olden days, some OGs like to fondly imagine them as the "golden days" of CCD cameras, people all struggled to try and maintain a 1:1 or 1:2 ratio between the imaging camera and guide camera.? This of course was absurd and only increased the likelihood of differential flexure due to all that extra mass and weight hanging off the main scope, obviously this was bad for guiding and everyone thought OAG was the way to go.? It still is bad for auto guiding, lower mass is more easily corrected and makes your back hurt less the next day if you are a portable imager with a larger optic and OAG use while much better still a PITA and more expensive.? Anyway as time as moved forward and autoguiding hardware and software has improved the ideal ratio has moved too.?

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I think the ideal ratio is now up to around 1:3 with good results and acceptable results on a good mount and heavy tripod (don't discount what a heavy tripod can add) out to 1:5 or so, once you get past around there stuff starts to get less reliable and at least my mount starts to behave less than ideally.? I know this because in my driveway I have tested the idea using that same old Stellarvue F050mm f4 (210mm measured fl) with a new ASI678MM screwed on the back of the helical focuser clamped rigidly to the top dovetail of an LX200 8" f/10 ACF (2,000mm) and LX200 10" f/6.3 EMC (1,600mm) SCTs with good results.? I have not managed to Barlow the ASI678MM yet but I expect it will return better results at 1:2.5.? Testing shows that the 1:1-1:2 ratio works extremely well with my very typical focal length refractors which range from 350mm to 802mm focal length refractors.? ? ? ? ? ? ? ? ?

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Anyway that's where I'm at at the moment.? Obviously, as per usual YMMV.??

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Thanks Gents

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I have a G2 tallboy on the way...ARM is hot.?? So needs new ARM and i'll try the new bootloader.?? I'll report back....shouldn't be to long

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cheers

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Brendan

On Tue, Apr 8, 2025 at 03:21 PM, Paul Kanevsky wrote:

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Very nice! But I think you need more weight on that mount to get it to full capacity ;)

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The mount with TOA and ASKAR has 42.6kg of counterweight

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Some more images, but the configuration has changed now. On the mount in the back is a Mewlon 250S 1st generation which I modified to ASCOM focuser using a slim 22mm? ? Faulhaber stepper motor with ZWO EAF electronics.

?

On the mount on the front the two Solar setup were replaced by the ASKAR 103APO.

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I also attached an image of the encoder disc on the worm wheel. This is not from a CEM 120EC2 but from a CEM 60EC.

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Rainer

On Tue, Apr 8, 2025 at 05:11 PM, Rainer wrote:

Those are iOptron CEM 120EC2

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On top a TOA 130 and ASKAR 103APO. BTW the chinese ASKAR telescopes are quality wise very very good. Takahashi is getting big competition. BTW I have a total of 5 Takahashi all bought in the years 2005 to 2010. Nowadays Takahashi is not worth. When I bought them there was no real good quality but nowadays chinese are showing what they are capable off.

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:-)

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Rainer

Those are iOptron CEM 120EC2

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On top a TOA 130 and ASKAR 103APO. BTW the chinese ASKAR telescopes are quality wise very very good. Takahashi is getting big competition. BTW I have a total of 5 Takahashi all bought in the years 2005 to 2010. Nowadays Takahashi is not worth. When I bought them there was no real good quality but nowadays chinese are showing what they are capable off.

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:-)

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Rainer

On Tue, Apr 8, 2025 at 04:26 PM, Rainer wrote:

stepper motors and encoder discs (big glass discs glued on the worm gear) on the RA and DEC axis

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Any photos? I'm curious to see what it looks like!

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Hi,

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Now that I am here I have a curiosity question. Those who knew from the times before 2018 back to >2008 when I still had my Losmandy G11-RS, know that I like to tinker, and improve?? (maybe make things worse :-0 ), everything I have.

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I have two mounts, big mounts with 52kg capacity(counterweights not included), with stepper motors and encoder discs (big glass discs glued on the worm gear) on the RA and DEC axis Worm gear with 360 teeth and 216mm ?.

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According to the producer the resolution of the encoder is 0.035" (arcseconds).

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Is it possible to use Gemini 2 with Stepper motors and the encoder discs?

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Rainer

NHSA Observatory

Mexico (in order to not create confusion)?? :-)