/g/Gemini_users

Re: Help troubleshooting after replacing Gemini 1 internal bettery

brenatlilydale@... (Brendan) — Tue, 08 Apr 2025 18:17:15 -0700

As others have said. It’ll be the motor (encoder pickup) or mainboard encoder read ICs PLDs. If you put Ra motor on DEC and it comes good. Then it’s a motor or cable issue.

You don’t need any settings in the gemini for it to boot and work. But it will default all setting back to Losmandy Titan mount and Losmandy lay/long. But it won’t know it’s dtg etc

But it will or should work! Changing the battery did not cause this unless you managed to stress the DIN socket solder joints and crack one. This would be very unlikely.

Might be an ESD Issue? Hard to say really If the board is bad. Send it to one of repairers.

cheers

Brendan

Re: Help troubleshooting after replacing Gemini 1 internal bettery

chiplouie@... (Chip Louie) — Tue, 08 Apr 2025 08:35:23 -0700

On Wed, Mar 12, 2025 at 08:24 AM, Franco Meconi wrote:

Hi all! I'm new to the group. I recently bought a Losmandy G11 running on Gemini 1 v1.04 from a friend. I've been setting it up and trying to configure it with NINA. I'd been having issues with the automated meridian flip with NINA issuing multiple flip commands when I came across a forum post where someone with the same issue had resolved it by changing the internal CR 2354 battery on the Gemini 1, which I did because I had no idea how long it had been since it had been replaced, and here's where my problems started.

As soon as I powered up the mount the RA motor started slewing at a very high speed, I had to almost immediately shut down the gemini to prevent the telescope from crashing into my pier. When I turned it back on the same thing happened, so I disconnected the motor cables from the Gemini and ran the setup using the hand controller (date and time, location, mount type, etc). I then switched it off, reconnected the motors and switched it back on for a warm restart, it seemed to be ok at first but as soon as I pressed one of the RA buttons on the hand controller the RA motor ran wild again at max speed, trying to slew west (I'm on the southern hemisphere, so that would be slewing east in the northern hemisphere, or lets just call it clockwise if you're behind the mount facing the celestial pole). When I tried to counter this slew with the hand controller it would show a MOTOR STALLED message on the hand controller. I tried replacing the battery again for the old one but the problem is still there.

Any help will be very appreciated!

Thanks,

Franco.

It seems that if the Gemini was working before the battery replacement that you have disturbed something when you pulled off the front panel and replaced the coin cell. I don't know which version you have but if this is an old one with RJ connectors for the servo motors they would be the first place to look. Try swapping the RA servo cable with the DEC servo cable, using the original Gemini. Does the issue remain? If run away slew is gone then replace the cables, be sure to use the right wiring orientation, there are at least two commonly being sold.

If the issue remains you may have a servomotor encoder issue or the Gemini has failed. Static discharge is a real danger and in opening the case you may have in advertently damaged something. It happens when no static precautions are used in the wrong conditions.

But lucky you have another working unit to use, hopefully while the other Gemini is being repaired. Good luck and keep us posted.

Chip Louie Chief Daydreamer Imagination Hardware

Astrospheric - South Pasadena

Re: Thoughts/recommendations concerning repair of Gemini 1

chiplouie@... (Chip Louie) — Tue, 08 Apr 2025 08:20:26 -0700

On Mon, Apr 7, 2025 at 01:45 PM, Rene Goerlich wrote:

This was my original design. Aveox soldered the green power LED instead of the red one onto it because their rules said that power LEDs have to be green, night vision wasn't that important then...

It's part of history... Please keep it alive and get this DEC PAL chip replaced 8)

René

LOL, I am sure that Brendan would replace the offending green LED with an appropriate red LED of Warren asked him to.

Chip Louie Chief Daydreamer Imagination Hardware

Astrospheric - South Pasadena

Re: Thoughts/recommendations concerning repair of Gemini 1

chiplouie@... (Chip Louie) — Tue, 08 Apr 2025 07:39:26 -0700

On Mon, Apr 7, 2025 at 10:29 AM, @wrvond wrote:

Well I did it.

I inadvertently used the wrong cables for the motors and smoked something. I used 6 pin RJ connectors instead of 8 pin RJ connectors. The display was working fine until I pressed a button on the hand control and it clicked, went blank and I smelled it release smoke inside.

Pulled the cover but don't see anything obviously fried. Installed the correct cables and powered up (cover removed).

It powers up but the Dec starts running - not exactly slewing but moving pretty fast. As soon as I touch an arrow button the Ra starts slewing. The only way to stop either is power off.

I appreciate your help.

Warren

Hi Warren,

Rene and the others here are right, the first generation Gemini controllers are an elegant solution at the advent of amateur astronomy's move to mechanisation and automation. It was a time when GOTO mounts were still still new and the old gods could still be seen. Of course that's just my OG romanticized view of my favorite hobby that has slipped into being monetized, over simplified and reduced to it most base for the masses.

Anyway, Michael Herman is our guy here in the USA to repair first gen Gemini 1 controller. If Michael can't fix it, he is a busy guy, I am confident that Brendan can but he is $100 round trip away in shipping. Brendan has my classic Gen I Gemini 2 Tall Boy to repair.

Chip Louie Chief Daydreamer Imagination Hardware

Astrospheric - South Pasadena

Re: Thoughts/recommendations concerning repair of Gemini 1

smff@... (rdoloc) — Mon, 07 Apr 2025 16:24:25 -0700

I have two of the original gemini 1 's 4 buttons on one side and no screen on the other side Of the hand controller

Re: Thoughts/recommendations concerning repair of Gemini 1

brenatlilydale@... (Brendan) — Mon, 07 Apr 2025 15:48:28 -0700

Warren. I cannot see anything obvious but I’d be looking at the two motor encoder PLD ICs (top right, Encoder 5V ) and D10/D9 dual diodes in sot23-3 package (bottom left, 5V lines).

This is fully repairable and as Rene�� says “a classic��!

cheers

Brendan

Re: Thoughts/recommendations concerning repair of Gemini 1

Rene@... (Rene Goerlich) — Mon, 07 Apr 2025 13:52:16 -0700

Paul,

Don't duck! There are screws to tilt the board upwards ;) ROTFL 8) Also, you can use the DeLuxe in parallel and get the information twice 8)

René

Am 07.04.25 um 22:18 schrieb Paul Kanevsky:

Re: Thoughts/recommendations concerning repair of Gemini 1

Rene@... (Rene Goerlich) — Mon, 07 Apr 2025 13:45:51 -0700

This was my original design. Aveox soldered the green power LED instead of the red one onto it because their rules said that power LEDs have to be green, night vision wasn't that important then...

It's part of history... Please keep it alive and get this DEC PAL chip replaced 8)

René

Am 07.04.25 um 22:18 schrieb Paul Kanevsky:

Re: Thoughts/recommendations concerning repair of Gemini 1

jim.bachesta@... (Jim Bachesta) — Mon, 07 Apr 2025 13:40:54 -0700

If you're willing to invest the money, you should consider sending the mount to Losmandy and upgrading to Gemini II, tune up and perhaps tucked motors. I did this with my old Losmandy and I have no regrets.

Re: Thoughts/recommendations concerning repair of Gemini 1

yh@... (Paul Kanevsky) — Mon, 07 Apr 2025 13:18:59 -0700

On Mon, Apr 7, 2025 at 03:48 PM, David C. Partridge wrote:

PS I’ve not see a Gemini-1 of that antiquity before!!!

I have one of these. It originally came with a simple, four button hand controller. You had to be next to the Gemini CPU to actually read anything on the LED, while simultaneously ducking, as soon you select a Goto :) The "Deluxe" hand controller with its own display came later.

Re: Thoughts/recommendations concerning repair of Gemini 1

david.partridge@... (David C. Partridge) — Mon, 07 Apr 2025 12:48:43 -0700

You almost certainly burnt out the motor encoders or decoders �� there may be other damage as well resulting from 12-18V getting into the 5V circuits.

Where are you based? That determines the choice of repairer �� Bren Smith in Australia, Michael Herman in California, and myself in the UK.

Looking at the “flying PCB�� I suspect you’ve sent this to Michael before now for repair.

PS I’ve not see a Gemini-1 of that antiquity before!!!

David

Re: Thoughts/recommendations concerning repair of Gemini 1

billmcdaniel@... (McDaniel, Bill) — Mon, 07 Apr 2025 11:50:21 -0700

You may want to contact Micheal Herman...he's the go to guy for Gemini repairs. You can reach him at Michael Herman <mherman346@...> As an aside I just noticed in your that he picture updated your memory/eprom? back in 2022

Thoughts/recommendations concerning repair of Gemini 1

wrvond@... (wrvond) — Mon, 07 Apr 2025 10:29:14 -0700

Well I did it.

I inadvertently used the wrong cables for the motors and smoked something. I used 6 pin RJ connectors instead of 8 pin RJ connectors. The display was working fine until I pressed a button on the hand control and it clicked, went blank and I smelled it release smoke inside.

Pulled the cover but don't see anything obviously fried. Installed the correct cables and powered up (cover removed).

It powers up but the Dec starts running - not exactly slewing but moving pretty fast. As soon as I touch an arrow button the Ra starts slewing. The only way to stop either is power off.

I appreciate your help.

Warren

Re: Reinstall G1 software

brenatlilydale@... (Brendan) — Thu, 13 Mar 2025 13:54:02 -0700

Totally agree with Paul. Put in a new battery, reset the Gemini power off and put in all Gemini 1 info, via Gemini ASCOM or by HC. Shut it down and re-boot it should be ok from there!

Generally most G1 “oddball issues �� are caused by corrupt data by low battery. The vast majority. But!

You did mention HC going blank and unresponsive. There is quite a few instances that can cause this (in most likely order): a bad CPU; SRAM Bad; EEPROM data corrupt a bad EEPROM.

But, we will worry about this if the battery doesn’t fix the issue.

cheers

Brendan

Re: Reinstall G1 software

yh@... (Paul Kanevsky) — Thu, 13 Mar 2025 09:18:10 -0700

The very first thing to check is to turn off Gemini, open it, take out the 3v battery, leave it out for a minute or two, then replace it with a fresh battery. I'd also check the HC cable and connectors, to make sure there's no break or intermittent contact. There's also a possibility that the F2 fuse is going bad, which has happened to many Gemini-1 units and can be diagnosed and repaired fairly easily: https://gemini-2.com/faqG1.html#Q13

If that doesn't help, you may want to program (or get an already programmed) EPROM chip with Gemini firmware and then swap it with the one that's installed. Beyond that, you may want to contact one of our independent repairers for help and troubleshooting: https://gemini-2.com/G1-repairers.html

Regards,

-Paul

On Thu, Mar 13, 2025 at 11:22 AM, David Pitre wrote:

Reinstall G1 software

farmerpitre@... (David Pitre) — Thu, 13 Mar 2025 08:22:14 -0700

My Gemini 1 Is not working.
I could get it to boot, start, and initially slew, but then the screen goes blank and is unresponsive.

Same thing with different hand controllers used.
Then recently another problem started.
After starting and going to an object search, the screen allows to enter the object, identify its location, but then, with another press of the button, it just goes back to object search.

It also has stopped tracking. Solar tracking is enabled (I just use this amount on the sun). And I could Move the telescope with a hand controller, but the mount does did not track.

I am wondering if my software is corrupted.

Is there a way to reinstall it?

Re: Testing G1 encoder port

manu.oliva.6e23@... (Ma Ol) — Wed, 12 Mar 2025 10:20:00 -0700

Hi there,

Look at the following URLs:

https://onstep.groups.io/g/main/topic/losmandy_g11_onstep/82492966

https://www.terransindustry.com/collections/onstep-v4-kit

http://stellarjourney.com/main/software-onstep-telescope-control/

https://onstep.groups.io/g/main

On Wed, Mar 12, 2025 at 5:40 PM David C. Partridge via groups.io <david.partridge=[email protected]" rel="nofollow noopener" target="_blank">[email protected]> wrote:

Re: Help troubleshooting after replacing Gemini 1 internal bettery

david.partridge@... (David C. Partridge) — Wed, 12 Mar 2025 09:49:29 -0700

Replacing the battery is pretty simple and after doing so you just need to re-enter your customisations (location, time etc.).

David

Re: Testing G1 encoder port

david.partridge@... (David C. Partridge) — Wed, 12 Mar 2025 09:48:09 -0700

There’s also the caveat that the support for shaft encoders may not be present in the Gemini-2 code. It was in the Gemini-1, but given how few of the Losmandy DSCH (their own shaft encoders) were sold, it’s possible that the code for that isn’t there in the Gemini-2.

René, if you see this, could you clarify the situation?

Thanks

David

Re: Testing G1 encoder port

david.partridge@... (David C. Partridge) — Wed, 12 Mar 2025 09:40:22 -0700

I don’t believe there are any high precision encoders that are compatible with the Gemini system, but I could be wrong.

I was looking at the Renishaw high precision absolute encoders but Scott wasn’t prepared to contemplate a solution that would cost around USD1400 per axis for him to purchase (so probably adding at least USD2000 per axis on the sale price). They’d also need an extra board/box to decode the signal format they use to something that the Gemini could use. I believe that these are what the super expensive mounts like 10-Micron or AP offer as a (costly) option.

Astro Devices sell some medium resolution relative encoders that provide about 4 arc-second resolution (311296 steps per revolution), but I don’t know if they are compatible with the Gemini system �� I think they intend them to be used with their own Nexus DSC Pro (digital setting circle) product. If you do want axis encoders it may be worth asking them.

David