Re: In search of 492 systems for G11 and GM8
Chip,
With only five mounts I don't consider myself a power user like you guys. I've got the Astro Devices DSC Pro on the other four mounts while this fifth mount happened to come with the Losmandy DSC. I figure I'll use it until I have saved up for another DSC Pro unit.? ?
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Not sure where you got your C11 from but even the lightest carbon fiber tubed USA made NS11 GPS SCT weighs more than 40 pounds when fully dressed for visual use. Granted this included Losmandy sourced V upper and D lower dovetails, Stellarvue 50mm f/4.2 RACI finder, large 3.25" mount Moonlite 2.5" focuser, 2" Baader BBHS Sitall diagonal and long 2" TeleVue eyepieces but they are not that much heavier than other similar items.?
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For imaging work the NS11 OTA is pushing 50 pounds, sometimes over depending on imaging configuration.? In any case this payload has never been a problem nor was the C14 payload an issue visually.?
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Because Losmandy mounts are not commodity mounts there is no need to estimate their imaging payload capacity using old wives tails for guidance.? Like AP, Losmandy has specified the maximum imaging payload for their mounts.? These payload limits are for commonly available optical tubes and they seem to work well as imaging payload guidelines.?
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As usual there are going to be some odd payloads that may prove difficult to manage but these optics will be on the periphery of the commonly available and used optics.??
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Losmandy GM811 (2022) with Pier extension for sale
Want to sell my Gemini II controller GM811 with Pier extension and larger saddle.? I find getting it out, down the stairs and setup each night a bit to much for my 70 year old body.? I am thinking $2,200 plus shipping.
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Purchasing a G11 with last version of the Gemini-1 controller
Hello,
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This weekend, I considering purchasing a Losmandy G11 with the latest Gemini with the last version of the Gemini-1 controller with untucked motors. The drive is about three hours. This would be my first German equatorial mount and my knowledge is limited. The present owner does not know anything about the mount, it is an estate sale. What should I look for - technical details and operation of the mount? A broad question, any pointers and ideas would be greatly appreciated. Included is an Explore Scientific ED127 with large Orion guide scope with an Orion StarShoot Autoguider. Utimately, my goals are astrophotography. Are there software limitations with this older version?
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Thank you,
Tom
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Well, the C11 weighs just under 40#s and it's OK. Planetary work doesn't involve long tracking intervals. It may be OK. The general rule is that your AP payload should be about 50% of the mount's max. The C11 violates that rule. That sort of supports the argument that the G11 is somewhat underrated.
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Re: What mount for Celestron 9.25
IIRC the 9.25 weighs about 25# and should be fine for visual on the GM-8. As I mentioned last week the Celestron G-9 model was a 9.25 on a GM-8 with a G11 dovetail saddle.
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Re: In search of 492 systems for G11 and GM8
Well, Brendan I have a long standing?grudge with the manufacturers of commercial?systems. It's based on a lot of things, lousy?support, extortionate parts prices, when parts are offered, woeful reliability and some pretty awful designs.?
In 2020 Steve Schwartz asked if I would?take on distribution?of the STMF103 based Blue Pill controller and his Espressif ESP32 based hand control parts kits, I accepted. As I pulled together an inventory of parts from Asia. I realized that most of the cost was the shipping. And if I ordered large 50-500 units the price of a kit could be cut drastically. If you go to AliExpress and JLBPCB and order the minimum parts needed for, say, a MaxESP3, it will run over a hundred. If I order?enough parts to build 40-50 it's under $20 for each controller. I add 20-30% for carrying costs so I can tell my wife I'm breaking even.
Why sell at cost? Remember my grudge, to expand the hobby to those who may be less able to afford a goto mount or repair the one they have and free others from having to deal with the manufacturers. It also gives me a purpose.
The D1-R32 is a ESP32 development board with an Arduino UNO configuration. $8-10 on AliExpress. The daughter?board was designed and placed in the public domain by a fellow in the Czech Republic who works for SAP. 50 ran about a buck a piece delivered. Resistors are a penny and caps about 2, males and female heads are 10? cents each, 12 to 3.3V power regulator is 58 -78 cents, RJs are a quarter, WiFi transceiver $1.50, RTC about the same. Add it up and it comes to $20 for the controller parts. Drivers are $4-$18 depending on your needs.
NEMA17 0.9° step angle motors are $10 delivered by 5 units. I generally?figure $15 per drive for toothed pulleys and belts and for commonally converted mounts, 3D motor bracket designs are available on the web. I generally put my faith in 6160, although?I used?scrap plastic for my GM-8 as an experiment. .?
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This whole situation sounds familiar, and my final fix was to replace the Gemini 2 PC board. That was several years ago when they were only $300, but now they are much more (see the Losmandy website). I did follow Brandan's helpful advice at that time, but we never found any cracks in the solder joints or the PC board, ergo process of elimination. The board is not that hard to remove, 4 screws on the cover and 4 holding the board inside the case - just for inspection.
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The only other things that might cause a stall after a good balance would be too much tension of worm against ring gear, depletion of lubricant, or too low a voltage in the supply. I switched from the standard Losmandy 15V adapter to the Michael Herman-built 17V unit, which helps to power through the tight spots with a little extra motor torque.?
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Good luck Fritz.
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John
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Losmandy G11G2 on pier; refurbed Losmandy G11 with OnStep controller; SkyShed design roll-off observatory; ZWO ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED with field flattener; Celestron C925 Edge HD with 0.7XFR, William Optics Zenithstar 61 APO; PHD2, NINA, Sequence Generator Pro and PixInsight user
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Fritz
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here is a image of the old STD motors.?? These components on the motor were for protection in Gemini 1 system and they can interfere with Gemini 2 encoder reading thus you "Can" get stalls.?? In fact I have seen them *these components on these motors) degrade over time and exposure to moisture.? So if you have these motors.?? The possible fix is remove the Zener Diodes (D1-D3) leave their space blank.?? Also remove F1-3...but jumper across their old pads with a short think wire link (so it won't hit the bottom of the motor housing)...Clean up with isopropanol and PCB resist....if you have some.
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Of course if you have HT motors....forget the above!
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.............While typing this.......I just learned that no matter what motor is on your DEC, its dead......so sorry its a Main Board issue?? are listed or (depends where you are ) is best option.
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Cheers
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Brendan  --
Brendan
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One extra thought Fritz is whether you have upgraded to L6 as part of your upgrade work? If so that is a little more sensitive to imbalances.
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I spent a little more time balancing my counter weights with my telescope and was mindful of the following from AP :-
"https://www.astro-physics.info/tech_support/accessories/mounting_acc/balance-to-optimize-guiding.pdf"
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It looks like you have a lot of good input from others so good luck.
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Ken
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Fritz, swap the Ra motor to DEC and visa versa. ?Did the fault follow the motor or stay in same axes?
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You can do this test with out installing the motors just do it on a bench. ?Mark which motor (and cable) is Ra and which is DEC! ? So as to not confuse them later. ?Which only complicates it all.
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If the fault stayed DEC then try swap cables to see if the fault ?changed axes!
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if in the first test swapping motors, if the fault moved to Ra it’s a motor issue. ? If it moved with the cable it’s a cable issue.?
If it stayed at DEC it’s a mainboard issue.?
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Get back on this pls. ?Also is it a “tallboy Gemini”? ?Some of these suffered hairline cracks between the motor socket on the main board (DEC in this case) ?and these caused all sorts of unusual motor issues. ?
Easily found with multimeter and or close magnifier inspection. ? Even measure from motor to Mainboard PCB pads while flexing moving the Din Cable! ? ?Just a little not a lot, you don’t want to break it…gently wriggle the plug in the socket! ? ?This can identify issues like the small cracks mentioned. ?
These are easily re-soldered but I like to desolder remove the old pin (it uses a cup/pin arrangement, under the socket) and solder in bigger pins.
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But your first step is to swap motors see what it does (wrt to the fault) and get back to us so we can advise further! ? ?Also tell us if it’s a “tallboyG2”?
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Oh, lastly ….are these the , maxon or HT motors?
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Some of the older STD motors, has diodes and zeners on its PCB that can interfere with the running on a G2 but usually only causes sped failure issues. ?But I have seen these components cause faults themselves. ?
So we need to know motor type. ? If it has 3 small fuses and zeners (look like diodes) on it.?
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cheers get back on all this.?
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Brendan
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I’ll have to look into third parties. Had no idea anyone else worked on them. I emailed Losmandy last night so we will see what I get back.?
It stalls at all slew speeds. I run at 200 to begin with (default is 800) for slew speeds to baby the mount with the RC10 on it. The DEC stalls even on very low center or guide speeds.?
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I don't know Gemini2, so there may not even be an option in there?but in Gemini1, there is an option to change the slew speeds. It might be worth reducing the slew rate on the DEC axis (if that's possible) and see if that makes a difference. At least it might tell you if it's mechanical or electric.
-- Thanks and Best Regards Neil
Hey all!
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I just rebuilt my observatory over the last ten months and had my 2017 G11G with Gemini 2 controller safely stored inside my house (A/C).?
I’ve remounted the G11G, but I’m having an issue I’ve never had before. My DEC axis is stalling. The scope is balanced (RC10) and has been used on that mount for years.?
What is very odd is that if I plug in the DEC motor to the RA output on the Gemini 2 it has no issue moving the mount in DEC. At first I thought was then just a cable swap issue. Unfortunately if I only swap the cables and don’t cross the DEC/RA outputs from the Gemini 2 I get the DEC stall error.
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I’m using the power cable I’ve always used (supplied by Losmandy). I also did replace the battery in the Gemini 2 since I remember when that gets low voltage things get… weird. That didn’t seem to have any effect.?
I did take the DEC gear cover off (exposing the two gears) and it’s very easy to spin those and spin the mount in DEC.?
Thank you!
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I think there are third parties who do repairs also.
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Thanks for the quick reply!
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I’ll have to open it up again tomorrow and see if there is an issue with the socket. The socket doesn’t seem loose.?
If I need to send the Gemini 2 in that likely means I won’t get to image this season here in central Florida. Last I talked to Losmandy about getting my G11G upgraded to have a titan RA it was a 6 month turnaround minimum. Obviously not the same thing but doesn’t give me confidence in a fast turnaround.?
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This sounds like an electronic failure of the circuitry that
drives the dec motor.? The last stage of the circuitry should be
the same for RA and dec motors, and your motor works with the
wrong one but not the right one.
You might look for loose connections inside, especially a problem
with the dec cable socket; otherwise it may be time to send your
Gemini off for repair.
On 2024-10-29 20:48, Fritz wrote:
Hey all!
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I just rebuilt my observatory over the last ten months and
had my 2017 G11G with Gemini 2 controller safely stored inside
my house (A/C).?
I’ve remounted the G11G, but I’m having an issue I’ve never
had before. My DEC axis is stalling. The scope is balanced
(RC10) and has been used on that mount for years.?
What is very odd is that if I plug in the DEC motor to the RA
output on the Gemini 2 it has no issue moving the mount in DEC.
At first I thought was then just a cable swap issue.
Unfortunately if I only swap the cables and don’t cross the
DEC/RA outputs from the Gemini 2 I get the DEC stall error.
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I’m using the power cable I’ve always used (supplied by
Losmandy). I also did replace the battery in the Gemini 2 since
I remember when that gets low voltage things get… weird. That
didn’t seem to have any effect.?
I did take the DEC gear cover off (exposing the two gears)
and it’s very easy to spin those and spin the mount in DEC.?
Thank you!
--
Michael A. Covington, Ph.D.
Consultant, Covington Innovations, Athens, Georgia, USA
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Hey all!
?
I just rebuilt my observatory over the last ten months and had my 2017 G11G with Gemini 2 controller safely stored inside my house (A/C).?
I’ve remounted the G11G, but I’m having an issue I’ve never had before. My DEC axis is stalling. The scope is balanced (RC10) and has been used on that mount for years.?
What is very odd is that if I plug in the DEC motor to the RA output on the Gemini 2 it has no issue moving the mount in DEC. At first I thought was then just a cable swap issue. Unfortunately if I only swap the cables and don’t cross the DEC/RA outputs from the Gemini 2 I get the DEC stall error.
?
I’m using the power cable I’ve always used (supplied by Losmandy). I also did replace the battery in the Gemini 2 since I remember when that gets low voltage things get… weird. That didn’t seem to have any effect.?
I did take the DEC gear cover off (exposing the two gears) and it’s very easy to spin those and spin the mount in DEC.?
Thank you!
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Re: In search of 492 systems for G11 and GM8
If you want a whole or parts of the DSC 492 system I suggest that you contact Losmandy directly. The still offer the DSC hand controller and drive boards in their Replacement Parts section. And they probably still have complete units laying around somewhere. BTW, I personally have the DSC system on two of my mounts (G11 and Starlapse) and like them very much.?
I am 74 years old and still enjoy star hopping to my sky targets like I did when I started imaging in 1975. It gives me a more intimate feeling and relationship with the sky vs GOTO. Furthermore, the DSC yields excellent long exposure autoguiding results if everything is set up and aligned correctly. And it is cheap.
I hope that you find your DSC. Best wishes.
John
On Wednesday, October 30, 2024 at 01:16:14 AM GMT+8, Chip Louie <chiplouie@...> wrote:
On Mon, Oct 21, 2024 at 05:30 PM, @wrvond wrote:
Thanks to Mark I'll soon have the 492 for my G-11.
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I'm still in the market for a 492 to go on a GM-8 with Losmandy DSC.??
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Not the Losmandy DSC!? Using that is like jumping back in time to vacuum tube calculation machines.? Its cool in theory but not IRL!??
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Re: In search of 492 systems for G11 and GM8
On Mon, Oct 21, 2024 at 05:30 PM, @wrvond wrote:
Thanks to Mark I'll soon have the 492 for my G-11.
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I'm still in the market for a 492 to go on a GM-8 with Losmandy DSC.??
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Not the Losmandy DSC!? Using that is like jumping back in time to vacuum tube calculation machines.? Its cool in theory but not IRL!??
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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On Fri, Oct 25, 2024 at 05:05 PM, Brian Maynard wrote:
I'm looking for some feedback from anyone who has their g11t loaded, over 70lbs.?
There may be few examples because the capacity of a GEM is based on the expected distance from the RA to the Center of Mass.? Observing the 16" OTA, it requires an additional 3 inches of distance to the center mass compared to the assumed capacity distance for the G11T.? Using the typical adjustments from the RA provides a reliable estimate of how the limits change with the counterweights required at the maximum limit at the standard OTA to RA axis distance.? If standard, the declination needs four 21-pound counterweights (84 pounds) to balance 90 pounds at 14.5 inches.? This becomes 75 pounds at 17.5 inches (90 pounds * 14.5/17.5), which is the new maximum allowed for visual observation.? This increase in RA axis spacing reduces capacity by 20%, positioning the mount not at the upper recommendation for photography but at or above the limit recommended for visual use.? Actual examples of this should be rare.
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As you might expect, we cannot increase capacity by adding more counterweight due to the role of inertia.? Shifting the OTA outward to this extent, while lowering the limit, also slightly alters the inertia.? However, adding weight exacerbates the issue for the mount, which is already at its maximum recommended load (torque on the RA).
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Doug
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Chip Louie
scottinharwood
Fritz