¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. Gemini_users
  2. Topics

Gremlin in Gemini I L4 hand controller

 

I have a Gemini I L4 which performs well except for the hand controller.? For a few minutes the HC acts just like it should, but eventually it starts to display gobbledy-gook and shortly afterward it shuts down.? The Gemini controller still has power and the motors are still tracking, but the HC appears to not have power and won't respond when the <menu> button is pressed (or any other button).
?
Even stranger, during the time the display is "junk", the HC continues to receive and send commands to my mount, if I can remember the menu tree well enough to enter my commands without the display confirming what I'm doing.??
?
I changed the internal battery last weekend.? I've restarted my controller several times.? Does anyone have any ideas?
 

¿ªÔÆÌåÓý

Where are you based?? If in UK, I repair Gemini-1 systems here.

?

See:

?

Cheers

David

?

From: [email protected] <[email protected]> On Behalf Of macdonjh via groups.io
Sent: 03 April 2022 13:26
To: [email protected]
Subject: [Gemini_users_io] Gremlin in Gemini I L4 hand controller

?

I have a Gemini I L4 which performs well except for the hand controller.? For a few minutes the HC acts just like it should, but eventually it starts to display gobbledy-gook and shortly afterward it shuts down.? The Gemini controller still has power and the motors are still tracking, but the HC appears to not have power and won't respond when the <menu> button is pressed (or any other button).

?

Even stranger, during the time the display is "junk", the HC continues to receive and send commands to my mount, if I can remember the menu tree well enough to enter my commands without the display confirming what I'm doing.??

?

I changed the internal battery last weekend.? I've restarted my controller several times.? Does anyone have any ideas?
 

Hi remember no need to cross post between forums for help.

Want to ask as some had fuse " fuse that was known to cause HC power etc issues.

However garbled display is not usually a symptom of a bad F2.?? It could be (usual culprits):
The CPU, only test by replacement, or feel if CPU is hot?
The EPROM, again test by replacement
The Displays themselves, The First display (LHS) overflows data to the 2nd RH display a bad first (LH) display can cause garbled issues.?? Test by swapping HC LH display t the RH position and the RH to the LH position.?? or
The HC itself could be the issue aka a bad U4 buffer IC.

All that said it is unusual to have garbled display and also power failure in the HC as generally they are separate things ...the only commonality is +5V being lost to the HC.?? The HC LED is actually powered from 5.4V.? Indeed you said the HC button presses would not respond so this again takes me back to possible loss of +5V to the HC.? Maybe a bad HC cable or corrosion around the HC cable socket.

So what I have given you is a starting point to look at the 5V and a few other things to look at and try.?? Get back if you need more help

regards




--
Brendan

gemini_hand_controller.jpg

 

I'm in the Colonies, but if it needs repair, shipping both ways would be worthwhile.



On Sunday, April 3, 2022, 08:30:23 AM CDT, David C. Partridge <david.partridge@...> wrote:


Where are you based?? If in UK, I repair Gemini-1 systems here.

?

See:

?

Cheers

David

?

From: [email protected] <[email protected]> On Behalf Of macdonjh via groups.io
Sent: 03 April 2022 13:26
To: [email protected]
Subject: [Gemini_users_io] Gremlin in Gemini I L4 hand controller

?

I have a Gemini I L4 which performs well except for the hand controller.? For a few minutes the HC acts just like it should, but eventually it starts to display gobbledy-gook and shortly afterward it shuts down.? The Gemini controller still has power and the motors are still tracking, but the HC appears to not have power and won't respond when the <menu> button is pressed (or any other button).

?

Even stranger, during the time the display is "junk", the HC continues to receive and send commands to my mount, if I can remember the menu tree well enough to enter my commands without the display confirming what I'm doing.??

?

I changed the internal battery last weekend.? I've restarted my controller several times.? Does anyone have any ideas?
 

Oops, I thought the G1 and G2 forums were separate.

Thank you, Brendan.? I have no idea what version of Gemini I is, but I'll look the next time I'm at my observatory.? I have the stuff to clean my contacts on the way.? Hopefully it is that simple.? I also have a known "good" cable, so I can try swapping cables as well (I didn't think of doing that until I was on my way home Sunday morning).? If neither of those tests work out I guess I will have narrowed the culprit down to the controller itself.? Fingers crossed that isn't the case.
 

¿ªÔÆÌåÓý

Ah but which colony? In USA Michael Herman is the guy who does repairs, and in Oz Bren Smith is your man.

?

D.

?

?

From: [email protected] <[email protected]> On Behalf Of macdonjh via groups.io
Sent: 05 April 2022 00:20
To: [email protected]
Subject: Re: [Gemini_users_io] Gremlin in Gemini I L4 hand controller

?

I'm in the Colonies, but if it needs repair, shipping both ways would be worthwhile.

?

?

?

On Sunday, April 3, 2022, 08:30:23 AM CDT, David C. Partridge <david.partridge@...> wrote:

?

?

Where are you based?? If in UK, I repair Gemini-1 systems here.

?

See:

?

Cheers

David

?

From: [email protected] <[email protected]> On Behalf Of macdonjh via groups.io
Sent: 03 April 2022 13:26
To: [email protected]
Subject: [Gemini_users_io] Gremlin in Gemini I L4 hand controller

?

I have a Gemini I L4 which performs well except for the hand controller.? For a few minutes the HC acts just like it should, but eventually it starts to display gobbledy-gook and shortly afterward it shuts down.? The Gemini controller still has power and the motors are still tracking, but the HC appears to not have power and won't respond when the <menu> button is pressed (or any other button).

?

Even stranger, during the time the display is "junk", the HC continues to receive and send commands to my mount, if I can remember the menu tree well enough to enter my commands without the display confirming what I'm doing.??

?

I changed the internal battery last weekend.? I've restarted my controller several times.? Does anyone have any ideas?
 

Mystery is likely solved.? I got my multi-meter out and found pin-12 is intermittent.? I haven't been able to find a pin-out for the Gemini I hand controller, so I don't know what signal pin-12 carries.? A new cable is on the way.
 

Mac

i posted a jpg cct of the HC above. ?Sone many years ago, not by me ? ?


pin 12 is Left LD which loads the left display with serial data characters. ? Since it¡¯s bad and data overflows from left to right yes you will have garbled display.

cheers
--
Brendan
 

Thanks, Brendan, I didn't even notice your attachment.
 

Mac¡­.I hope it¡¯s Mac it¡¯s hard to tell ?you really need a name in signature. ?Just makes it easier to be a bit more personnel in replying.?


It¡¯s kinda unusual to have a bad HC pin/cable ? ?So do check the main PCB and or HC sockets for corrosion and or bad solder join. ?Seen Main PCBs with corrosion around this J1 socket ??


The G1¡¯s are starting to show some corrosion after decades of use. ? Depends upon usage, location, humidity. ? ?A clean up and re-coat of spray conformal will protect it for years to come.

Any issues fire away! ?You found the fault well done! ? Certified ¡°champ¡±!
--
Brendan
 

Thanks, Brendan.? I'm confident the cable is bad, but your recommendation about checking the board for corrosion and bad joints is good.? I'll do that, too.? Thanks, also for the lead about conformal.? I will check that out.

Mac is fine.
 

New cable is here and Gemini seems happier.? That Conformal is expensive stuff, at least I have two Gemini units to treat with it.? Is there any difference between the Techspray, the MG Chemicals and CRC offerings?? Is there any reason to choose the silicone formula over the acrylic for our application?
 

Just use the Acrylic sprays. ?Silicon conformal is too expensive for non pro stuff aka this is for avionics of naval electronics. ?

Cap any sockets snd plugs before use. Indeed I wouldn¡¯t spray ICs that are socketed like CPU/Pic42s/EPROM ETC. ?These need good contact surfaces. You don¡¯t need a thick coating. ?Indeed usually spray into cap and brush it on as necessary.?


Clean up with acetone?

cheers, well done?
--
Brendan
 

Oh sorry I use cheap stuff ! ?What ever onsale.?
--
Brendan
Brian Valente
 

¿ªÔÆÌåÓý

This isn¡¯t an official Losmandy recommendation but I¡¯ve used this with good results and it¡¯s fairly inexpensive

?

?

?

?

?

Thanks

?

Brian

?

Brian Valente

Losmandy Astronomical

?

Losmandy.com

Tutorials and vids at

?

From: [email protected] [mailto:[email protected]] On Behalf Of macdonjh via groups.io
Sent: Sunday, April 10, 2022 12:17 PM
To: [email protected]
Subject: Re: [Gemini_users_io] Gremlin in Gemini I L4 hand controller

?

New cable is here and Gemini seems happier.? That Conformal is expensive stuff, at least I have two Gemini units to treat with it.? Is there any difference between the Techspray, the MG Chemicals and CRC offerings?? Is there any reason to choose the silicone formula over the acrylic for our application?

 

Thank you, Brendan and Brian.? I noticed Amazon's prices for the Techspray were 40% less than Grainger.? Yikes.? I'll get a smaller container of the brush-on stuff.? Thanks again for the recommendations.

1 - 16 of 16