Re: Settings for use of AutoGUIDE
I have gone through my "tutorial" and updated it since i have learned stuff since i first wrote i have also reduced the amount of text.
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/Gabriel
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Re: Settings for use of AutoGUIDE
Thank you for clarifying on backlash Gary!
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/Gabriel?
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Re: Settings for use of AutoGUIDE
FYI
If you are going to remove the backlash by 'last moves' you need to be aware of the sidereal direction which is a function of where you are in the sky.?
So if you are east, at 90/38, Gabriel, then the sidereal movement for AZ is clockwise and for ALT it is UP. This will apply from a point that is 90-LAT and greater in both AZ and ALT. If you are north and east of this then it is still UP for ALT but CCW for AZ.?
If you move past the meridian, 180¡ã or directly south, then the sidereal direction is CW for AZ and DWN for ALT.?
So to 'remove lash' you would move in the opposite direction by at least 2 or 3¡ã (no more is necessary as the most lash will be is in the 15 arcmin region and that would be huge). THEN move per the above to remove the lash. Don't use the opposite buttons or you will need to repeat at least in that axis.?
Note the latest version firmware does this automatically. It is called LMIS (Last Move is Sidereal). Also AutoLOCK will remove lash automatically as well - however because I didn't want to have excessive movement in the eyepiece (visual use) when using AutoLOCK I, by design, made the max speed changed fixed at a lower value so it might take a minute or longer to resolve backlash. AutoLOCK allows you to look in the EP and recenter an object - it then locks this new location as the reference location (this is all when using the Argo Navis)... if the last move was counter-sidereal then lash will have been introduced and will need to be resolved. So if that is the case the object will drift until it brings it back to the center.?
Gary
------ Original Message ------
Date 4/4/2025 7:16:33 AM
Subject Re: [ServoCAT] Settings for use of AutoGUIDE
[Edited Message Follows]
Hi Mike,
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No, when using the ST4 cable and checking "use dec compensation" in PHD2 settings you only have to calibrate once in the beginning of the evening. At the moment i calibrate at about 90 AZ and 38 ALT, works well.
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If you don't connect to the mount in PHD2 you will be promted to enter the dec (alt) before calibration and before starting to guide, if you connect to a mount driver PHD2 will automatically know where the scope is pointing in the sky.
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if you check "Auto-restore calibration" in PHD2 settings you will not have to calibrate upon each new session either.
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However my take is, that since the scope due to say humidity or some other factor may move mor easily one night than another pherhaps it's best to calibrate before each session so that PHD2 understands how the scope behaves that night, and you will also see that if the measured guidespeed is a lot less than the previous session pherhaps the bearings are not clean ore something like that which you could adress before imaging.
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But my guess is you could probably get away with calibrating once then just imaging night after night.
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Actually i avoid objects below 40 degrees so i often begin right around there so it has not been an issue getting 2-3 hours on an object provided i do som planing in Stellarium.
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To be really effective and minimize the effects of field rotation you can do 30-60 minutes on several objects during a night and continue adding time on them several nights at the same position they where the previous nights, so after many nights you would have many objects with much time where the frames will not have been rotated that much compared to tracking a single object one night for 3 hours.
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I also had massive backlash and did Gary's procedure however backlash comp does not work with autoguiding for some reason, the stars look like the scope has been hit by a wind gust, it's even written in PHD2 documentation to not use any backlash compensation outside the software.
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So i set the backlash comp to 0 in both alt and az in ServoCAT Sky and thought it would be a disaster, but no problem at all. As long as you slew UP untill the scope moves before doing PHD2 calibration no problem, and when autoguiding it has not been a problem at all either, pherhaps the motors never change directions only speed.
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I am a bit confused, because in PHD2 my scope shows less backlash than the dedicated AP rig i had (when changing from north step to south step). With the Virtual handpad in NINA backlash is more evident and with the physical handpad my backlash in alt is massive.
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My guidescope only has a focal length of only 180mm so no problem!?
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/Gabriel
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Re: Settings for use of AutoGUIDE
Hi Mike,
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No, when using the ST4 cable and checking "use dec compensation" in PHD2 settings you only have to calibrate once in the beginning of the evening. At the moment i calibrate at about 90 AZ and 38 ALT, works well.
?
If you don't connect to the mount in PHD2 you will be promted to enter the dec (alt) before calibration and before starting to guide, if you connect to a mount driver PHD2 will automatically know where the scope is pointing in the sky.
?
if you check "Auto-restore calibration" in PHD2 settings you will not have to calibrate upon each new session either.
?
However my take is, that since the scope due to say humidity or some other factor may move mor easily one night than another pherhaps it's best to calibrate before each session so that PHD2 understands how the scope behaves that night, and you will also see that if the measured guidespeed is a lot less than the previous session pherhaps the bearings are not clean ore something like that which you could adress before imaging.
?
But my guess is you could probably get away with calibrating once then just imaging night after night.
?
Actually i avoid objects below 40 degrees so i often begin right around there so it has not been an issue getting 2-3 hours on an object provided i do som planing in Stellarium.
?
To be really effective and minimize the effects of field rotation you can do 30-60 minutes on several objects during a night and continue adding time on them several nights at the same position they where the previous nights, so after many nights you would have many objects with much time where the frames will not have been rotated that much compared to tracking a single object one night for 3 hours.
?
I also had massive backlash and did Gary's procedure however backlash comp does not work with autoguiding for some reason, the stars look like the scope has been hit by a wind gust, it's even written in PHD2 documentation to not use any backlash compensation outside the software.
?
So i set the backlash comp to 0 in both alt and az in ServoCAT Sky and thought it would be a disaster, but no problem at all. As long as you slew UP untill the scope moves before doing PHD2 calibration no problem, and when autoguiding it has not been a problem at all either, pherhaps the motors never change directions only speed.
?
I am a bit confused, because in PHD2 my scope shows less backlash than the dedicated AP rig i had (when changing from north step to south step). With the Virtual handpad in NINA backlash is more evident and with the physical handpad my backlash in alt is massive.
?
?
My guidescope only has a focal length of only 180mm so no problem!?
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/Gabriel
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Re: Settings for use of AutoGUIDE
Gabriel,
I am still trying to understand all of this. One big question I have is: does calibration need to be done for every object or every session?
Also I think an issue for me is going to be a limitation in objects with a decent enough imaging length because my horizon up to about 40 degrees is obstructed all around me due to trees.
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I think if I try this with my dob (A 18¡± f4.3 Astrosystems) mechanically, at least might work well since I have combination Teflon and roller bearings mitigating any stiction in az or alt. I do have a lot of backlash in both axes that I need to counteract using Gary¡¯s excellent procedure.
For possible guidescopes I currently only have 2 options 1) An 80mm Lumicon Superfinder. Not sure of its fl but I believe it is very short so may not work. Other option is a Primaluce Lab 60mm guide scope that is 240mm fl. Which might work
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Mike
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Re: ServoCAT Autoguiding breakthrough
Thanks Gabriel for the info, I have a couple of those cords.
Mickey
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On Mar 31, 2025, at 6:50?AM, Gabriel Wiklund via groups.io <gabriel.wiklundholeshot@...> wrote:
? [Edited Message Follows]
If you can find the industry equivalent which is 6P6C RJ12 that is 10 FT long (it was in stock in a local shop here in Sweden) you will save money since it's "not for astronomy".
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10 FT should be enough for your scope since it worked but was at the very limit on my scope (that's why i got a longer cable).
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I think the 6P6C RJ12 cable is used for switchboards if that helps regarding which shop you would go to.
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/Gabriel
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Edit: RJ12 6P6C in both ends
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Edit again: Forgot to answer your question lol, here is the 5 meter cable i got:
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Re: ServoCAT Autoguiding breakthrough
If you can find the industry equivalent which is 6P6C RJ12 that is 10 FT long (it was in stock in a local shop here in Sweden) you will save money since it's "not for astronomy".
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10 FT should be enough for your scope since it worked but was at the very limit on my scope (that's why i got a longer cable).
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I think the 6P6C RJ12 cable is used for switchboards if that helps regarding which shop you would go to.
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/Gabriel
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Edit: RJ12 6P6C in both ends
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Edit again: Forgot to answer your question lol, here is the 5 meter cable i got:
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Re: ServoCAT Autoguiding breakthrough
Thanks again Gabriel , one last question LOL, where did you get an st4 cable long enough to go from the UTA down to the ServoCat?
Mickey?
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On Mar 30, 2025, at 3:44?PM, Gabriel Wiklund via groups.io <gabriel.wiklundholeshot@...> wrote:
? Yes it's a 50mm finder. It's monted with one screw without any Velcro, i think what you are seeing is masking tape which i used to not damage the paint job. It is important that the Guidescope does not flex since only a few microns (thinner than a human hair) of movement is something like 6 arc seconds in the sky which would be a wobble as wide as at least 2 stars.
You might discover a solution i have not thought of.
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/Gabriel
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Re: ServoCAT Autoguiding breakthrough
Yes it's a 50mm finder. It's monted with one screw without any Velcro, i think what you are seeing is masking tape which i used to not damage the paint job. It is important that the Guidescope does not flex since only a few microns (thinner than a human hair) of movement is something like 6 arc seconds in the sky which would be a wobble as wide as at least 2 stars.
You might discover a solution i have not thought of.
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/Gabriel
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Re: ServoCAT Autoguiding breakthrough
Thank you Gabriel? The scope looks like a 50mm finder scope ??? I have an Orion 55mm finder scope and can easily mount it just like you did using Velcro, correct?
Mickey
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On Mar 30, 2025, at 2:47?PM, Gabriel Wiklund via groups.io <gabriel.wiklundholeshot@...> wrote:
? Thank you Mickey!
Sure, here you go:
First here you have the AUX/AG port on the back of the ServoCAT where you plug in the ST4 cable. <20250225_220356.jpg> ?
Then the ST4 cable goes to the back of the Guidecamera. My cable is overkill (5 meters long) but
no issues so far, i think i could get away with 3 meters though.
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Here is the Guidescope i use:
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Comes with these mounting options:
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<51Q3AA3GjpL._AC_SX425_.jpg> ?
I use the one to the far right and just 1 screw from the telrad finder base to mount it on the scope.
I know it sounds sketchy but the guidescope is very light and it does work, pherhaps you have an even better idea.
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I recommend using a simple DIY dewshield.
Finally you plug the supplied USB cable that came with the Guidecamera to your USB hub or PC.
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Re: ServoCAT Autoguiding breakthrough
Thank you Mickey!
Sure, here you go:
First here you have the AUX/AG port on the back of the ServoCAT where you plug in the ST4 cable.  ?
Then the ST4 cable goes to the back of the Guidecamera. My cable is overkill (5 meters long) but
no issues so far, i think i could get away with 3 meters though.
?
?
?
Here is the Guidescope i use:
?
Comes with these mounting options:
?
?
I use the one to the far right and just 1 screw from the telrad finder base to mount it on the scope.
I know it sounds sketchy but the guidescope is very light and it does work, pherhaps you have an even better idea.
?
I recommend using a simple DIY dewshield.
Finally you plug the supplied USB cable that came with the Guidecamera to your USB hub or PC.
?
?
?
?
?
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Re: ServoCAT Autoguiding breakthrough
Gabriel that's outstanding. 2 weeks I ago I wanted to test the new nexus firmware I finally installed . At the start I started having WiFi problems. I called Serge and we figured out the WiFi problem I had been having on and off was due to a bad WiFi card. Serge sent me a new one and Nexus is working perfectly. I hope to text TUESDAY night EST using SharpCap recenter image using plate solving w goto and nexus Astro lock.? ? You may have done this in the past but I can't find it. Send me a picture of how your guide scope and camera are installed on your star structure please.
Thank you Mickey?
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On Mar 30, 2025, at 9:18?AM, Gabriel Wiklund via groups.io <gabriel.wiklundholeshot@...> wrote:
? [Edited Message Follows]
I had read online that Multi-star guiding does not work with alt/az mounts due to field rotation. Yesterday i gave it a try just for fun, and it not only works but the difference is day and night, i went between the two methods several times and it was like pressing an on/off switch.
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Guiding before was around 1.5" arc seconds total RMS, with Multi-star it went down to 0.7"-0.9" arc seconds total RMS.
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Here is a PHD2 screenshot, the 0.69" arc seconds total RMS displayed there was for the previous 2.5 minute guideperiod using 1.5 sec exposures on the guidecam:
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Here is the stacked image of NGC 6946 from yesterdays session, only 43 minutes (128x20s):?
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<43m NGC 6946 Processed.png> ?
Dynamic PSF stats from Siril:
FWHMx: ? ?2.95"
FWHMy: ? ?2.72"
r:? ? ? ? ? ? ? ? 0.925
The best 20 second sub of the night had a FWHM of 2.35" arc seconds.
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To give some perspective i was getting 2.50"-2.80" when doing 1 second test exposures in the beginning of the session after the seeing got better.
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I remember when using the 30" for visual before i even had adjusted the gear ratios, the above scenario would have sounded impossible at best!
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Clear skies
Gabriel
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Edit: The significant crop is because the bright stars away from the galaxy had an ugly halo around them due to some fog on my CC lens at the end of the session.
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Re: ServoCAT Autoguiding breakthrough
Thank you Gary,
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Indeed!
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/Gabriel
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Re: ServoCAT Autoguiding breakthrough
Fantastic job Gabriel! Congratulations...?
I will say the ServoCAT system is doing a great job... but one very important key here is how well Mike "tunes" his custom telescopes. The ability to move that large of a scope at extremely slow speeds with friction interfaces (not ball bearing) is incredible and a direct result of his efforts.?
Keep going...?
Gary Myers StellarCAT
------ Original Message ------
Date 3/30/2025 9:10:46 AM
Subject [ServoCAT] ServoCAT Autoguiding breakthrough
I had read online that Multi-star guiding does not work with alt/az mounts due to field rotation. Yesterday i gave it a try just for fun, and it not only works but the difference is day and night, i went between the two methods several times and it was like pressing an on/off switch.
?
Guiding before was around 1.5" arc seconds total RMS, with Multi-star it went down to 0.7"-0.9" arc seconds total RMS.
?
Here is a PHD2 screenshot, the 0.69" arc seconds total RMS displayed there was for the previous 2.5 minute guideperiod using 1.5 sec exposures on the guidecam:
?
?
Here is the stacked image of NGC 6946 from yesterdays session, only 43 minutes (128x20s):?
?
?
Dynamic PSF stats from Siril:
FWHMx: ? ?2.95"
FWHMy: ? ?2.72"
r:? ? ? ? ? ? ? ? 0.925
The best 20 second sub of the night had a FWHM of 2.35" arc seconds.
?
To give some perspective i was getting 2.50"-2.80" when doing 1 second test exposures in the beginning of the session after the seeing got better.
?
I remember when using the 30" for visual before i even had adjusted the gear ratios, the above scenario would have sounded impossible at best!
?
Clear skies
Gabriel
?
?
?
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ServoCAT Autoguiding breakthrough
I had read online that Multi-star guiding does not work with alt/az mounts due to field rotation. Yesterday i gave it a try just for fun, and it not only works but the difference is day and night, i went between the two methods several times and it was like pressing an on/off switch.
?
Guiding before was around 1.5" arc seconds total RMS, with Multi-star it went down to 0.7"-0.9" arc seconds total RMS.
?
Here is a PHD2 screenshot, the 0.69" arc seconds total RMS displayed there was for the previous 2.5 minute guideperiod using 1.5 sec exposures on the guidecam:
?
?
Here is the stacked image of NGC 6946 from yesterdays session, only 43 minutes (128x20s):?
?
?
Dynamic PSF stats from Siril:
FWHMx: ? ?2.95"
FWHMy: ? ?2.72"
r:? ? ? ? ? ? ? ? 0.925
The best 20 second sub of the night had a FWHM of 2.35" arc seconds.
?
To give some perspective i was getting 2.50"-2.80" when doing 1 second test exposures in the beginning of the session after the seeing got better.
?
I remember when using the 30" for visual before i even had adjusted the gear ratios, the above scenario would have sounded impossible at best!
?
Clear skies
Gabriel
?
Edit: The significant crop is because the bright stars away from the galaxy had an ugly halo around them due to some fog on my CC lens at the end of the session.
?
?
?
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Re: Servocat unit not responding
Rajeev,
Ok ... so first off did you go in to the settings for the Sky Commander and check them? The default value is not 9600!?
Second are you sure you have the 2 jumpers behind the front jack lined up with the silked screened (white) text on the printed circuit board - marked "SC"??
Last are you sure the jumper is on covering both pins and still 4 from the end??
Gary?
------ Original Message ------
Date 3/28/2025 3:41:55 PM
Subject Re: [ServoCAT] Servocat unit not responding
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Hi, Gary,
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I tried again, by moving the 4th jumper to connect both pins, and trying the ServoCat with Sky Commander again.? But the red DSC light still doesn't come on.
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I'm next going to replace the lithium battery in my AN, and see if that connects with the jumpers restored to their previous positions.? If that doesn't work, I'll need to have Bill take a look to make sure the unit is working fine.
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Thanks again for all your help,
- Rajeev
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Re: Servocat unit not responding
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Hi, Gary,
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I tried again, by moving the 4th jumper to connect both pins, and trying the ServoCat with Sky Commander again.? But the red DSC light still doesn't come on.
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I'm next going to replace the lithium battery in my AN, and see if that connects with the jumpers restored to their previous positions.? If that doesn't work, I'll need to have Bill take a look to make sure the unit is working fine.
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Thanks again for all your help,
- Rajeev
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Re: Servocat unit not responding
Rajeev,
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Re the comment about not connecting via ASCOM. It won't connect unless the DSC is connected to the ServoCAT and aligned. This is a prerequisite. And of course as you've found the jumper is the reason, or at least one reason, why it wouldn't have connected to the new unit.
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Gary?
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Re: Servocat unit not responding
Rajeev,
Ok - thanks for info re older unit. Bill took care of you there. Good to know.?
As for the jumper - yes - it has to be across those 2 pins (9600 baud forced) and not off of one (which is for 19200 baud).?
g.
------ Original Message ------
Date 3/28/2025 11:24:29 AM
Subject Re: [ServoCAT] Servocat unit not responding
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Hi, Gary,
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Thanks for the detailed response.? I had sent the old (Gen3 ServoCat Jr) unit back to Bill in December, but after inspection, he said it couldn't be repaired.? That's how I ended up buying a new (regular ServoCat) unit.
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I'll have to dig out my old ServoCat Jr unit, but the new one shows that the 4th jumper is just off one pin.? Should I try putting it across both pins and checking if it recognizes the Sky Commander? (The box says "Sky Comander XP4 Flash", and when I turn it on, it shows the version as "512k Flash v5.03".)
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Thanks again for all your help,
- Rajeev
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Re: Servocat unit not responding
?
Hi, Gary,
?
Thanks for the detailed response.? I had sent the old (Gen3 ServoCat Jr) unit back to Bill in December, but after inspection, he said it couldn't be repaired.? That's how I ended up buying a new (regular ServoCat) unit.
?
I'll have to dig out my old ServoCat Jr unit, but the new one shows that the 4th jumper is just off one pin.? Should I try putting it across both pins and checking if it recognizes the Sky Commander? (The box says "Sky Comander XP4 Flash", and when I turn it on, it shows the version as "512k Flash v5.03".)
?
Thanks again for all your help,
- Rajeev
?
?
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Gabriel Wiklund
Mike