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Super greasy worm gears on my GM8
Hello. This is my first post here and I'm very happy to have found this group. I own a GM8 that's apparently from the 90's. I've used it with autoguiding to take 5 minute exposures without problems and that's good enough for me. The tracking seem to be working well. I'm gonna clean and relubricate the clutches (with Super lube as suggested by y'all) but I don't know what to do with the worm bearings. They look super greasy and dirty but I am very cautious since I don't want to do anything unnecessary as it is currently doing what it should. Here are the images of the RA and DEC worm bearings: RA: DEC: Should I worry about this or just let it be? Thanks, Fredrik ? |
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Re: Motor stalled.......
You should use the ATF16V8BQL, rather than the ATF16V8B, as that is the only one that drops into low power mode when it has no signal transitions on the inputs.
Dave From: Losmandy_users@... [mailto:Losmandy_users@...] Sent: 10 October 2017 16:56 To: Losmandy_users@... Subject: Re: [Losmandy_users] Re: Motor stalled....... OK. I've ordered 10 of these chips, and I found a 20-pin DIP to SOIC socket on eBay to allow me to program these. Next steps... await the experiment... of giving it a try.... and talking to John...! Best, Michael On Tue, Oct 10, 2017 at 8:42 AM, Michael Herman <mherman346@...> wrote: OK. I see the chip listed here in the Mouser catalog as: Atmel made these in the 20-pin SOIC (small outline IC) package -- no one else made the product in that package. They are $0.95 each from Mouser, + lowest shipping charge $5. The datasheet is here: The problems will be getting a DIP to 20-pin SOIC socket to program these, and to see if my existing programmer with its DIP socket will work.. It is ironic that Atmel is near me in San Jose... they got bought by Microchip recently... Best, Michael On Tue, Oct 10, 2017 at 8:09 AM, mknwfhccabsgfi2b7fvsii57vq43ikvdv4r3sfuo@... [Losmandy_users] <Losmandy_users@...> wrote: Micheal, I will call you this evening. John -- Michael Herman mobile: 408 421-1239 <tel:(408)%20421-1239> email: mherman346@... -- Michael Herman mobile: 408 421-1239 email: mherman346@... [Non-text portions of this message have been removed] |
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Re: Motor stalled.......
how can we Gemini owners prevent such damage in the first place? The most common cause of these problems is (as I understand it) mis-connecting the motor DIN plugs. I know they are polarized but I¡¯m told it¡¯s still possible to mis-plug them. Dave From: Losmandy_users@... [mailto:Losmandy_users@...] Sent: 10 October 2017 15:00 To: Losmandy_users@... Subject: RE: [Losmandy_users] Re: Motor stalled....... I have fortunately not found Gemini units with this damage - yet. I cannot yet do that repair, as I have not yet developed the programming kit to make these replacements, but I will look into that. Better: Can anyone say what is causing these chips to fail? Is there a simple preventative measure owners can take to avoid such damage? Best, Michael On Oct 10, 2017 4:33 AM, "'David C. Partridge' david.partridge@... [Losmandy_users]" <Losmandy_users@...> wrote: The decoder ICs U15 and U16 are no longer obtainable from Losmandy or Aveox. However they are just AFT16V8BQL-15SU PLDs which need to be programmed. I have the jedec file to program them if you have a suitable programmer and SOIC adapter. The two ICs are the SOIC-20 parts at the upper right edge of the G-1 PCB. You'll need hot air soldering kit or "Chip-Quik" to remove them. If you aren't comfortable doing that then either Michael Hermann or I can repair for you (I'd suggest Michael if you are in USA as I live in the UK). You can test the shaft encoder with the motor removed from the mount and without the Gemini controller. Use a 5V supply, ground to pin 1, +5V to pin 4 of the HEDS-9100. You can then turn the motor pinion by hand and observe the signals on pins 3 and 5 HED-9100. If you only get a signal on one or neither, then replace the encoder. Clear skies Dave Partridge [Non-text portions of this message have been removed] |
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Re: Motor stalled.......
OK.? I've ordered 10 of these chips, and I found a 20-pin DIP to SOIC socket on eBay to allow me to program these. Next steps... await the experiment... of giving it a try.... and talking to John...! Best, Michael On Tue, Oct 10, 2017 at 8:42 AM, Michael Herman <mherman346@...> wrote:
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Re: Motor stalled.......
OK.?? I see the chip listed here in the Mouser catalog as: Atmel made these in the 20-pin SOIC (small outline IC) package -- no one else made the product in that package.?? They are $0.95 each from Mouser, + lowest shipping charge $5.?? The datasheet is here:? The problems will be getting a DIP to 20-pin SOIC socket to program these, and to see if my existing programmer with its DIP socket will work..?? It is ironic that Atmel is near me in San Jose... they got bought by Microchip recently...? Best, Michael On Tue, Oct 10, 2017 at 8:09 AM, mknwfhccabsgfi2b7fvsii57vq43ikvdv4r3sfuo@... [Losmandy_users] <Losmandy_users@...> wrote:
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Re: Motor stalled.......
Hi John, You can reach me, Michael Herman, at? email: mherman346@... or by phone (I'm in California) at 408 421-1239 I suggest you call me to discuss this problem.?? Best,? Michael On Tue, Oct 10, 2017 at 7:50 AM, mknwfhccabsgfi2b7fvsii57vq43ikvdv4r3sfuo@... [Losmandy_users] <Losmandy_users@...> wrote:
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Re: Motor stalled.......
Thanks David for the advice. I now see the IC's on the board now. I wonder if it would be worth swapping them to see if the problem changes to the RA instead of the DEC. In the mean time, How can I contact Micheal in the US? Also, how do I check for signals on the encoder? Not sure If I have the proper equipment.
Thank you very much! |
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Re: Motor stalled.......
I have fortunately not found Gemini units with this damage - yet.? I cannot yet do that repair, as I have not yet developed the programming kit to make these replacements, but I will look into that.? ? Better: how can we Gemini owners prevent such damage in the first place? Can anyone say what is causing these chips to fail??? Is there a simple preventative measure owners can take to avoid such damage? Best, Michael? On Oct 10, 2017 4:33 AM, "'David C. Partridge' david.partridge@... [Losmandy_users]" <Losmandy_users@...> wrote:
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Re: Motor stalled.......
The decoder ICs U15 and U16 are no longer obtainable from Losmandy or Aveox. However they are just AFT16V8BQL-15SU PLDs which need to be programmed.
I have the jedec file to program them if you have a suitable programmer and SOIC adapter. The two ICs are the SOIC-20 parts at the upper right edge of the G-1 PCB. You'll need hot air soldering kit or "Chip-Quik" to remove them. If you aren't comfortable doing that then either Michael Hermann or I can repair for you (I'd suggest Michael if you are in USA as I live in the UK). You can test the shaft encoder with the motor removed from the mount and without the Gemini controller. Use a 5V supply, ground to pin 1, +5V to pin 4 of the HEDS-9100. You can then turn the motor pinion by hand and observe the signals on pins 3 and 5 HED-9100. If you only get a signal on one or neither, then replace the encoder. Clear skies Dave Partridge |
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Re: Motor stalled.......
Thanks for all the advice guys! Did some checking today and it seems to be either the DEC encoder U15/16 or the optical encoder on the motor. The encoder is $51.00 US plus shipping. I'll start with U15/16 which I can't locate on the pcb for some reason. How can I purchase one of these in the USA?
Thanks John |
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Re: Motor stalled.......
Not tried to read those yet, it is the soldered on quadrature decoder chips that I can make. The PIC17C42 ICs I have yet to attempt.
Dave From: Losmandy_users@... [mailto:Losmandy_users@...] Sent: 09 October 2017 06:48 To: Losmandy_users@... Subject: Re: [Losmandy_users] Re: Motor stalled....... If it is the U15 or U16 chip, then David Partridge in the UK has these or can make them. I have not yet tackled that. These chips are in sockets on the main board and can easily be pulled out (say with an automotive sharp hook tool) and replaced by the owner. If it is the motor's encoder element, then, again, I have no experience with that trouble. In either case, I am surprised the prior owner did not experience the problem and that John, who just acquired the system, is stuck with this problem from his first experience. Best of luck, Michael On Sun, Oct 8, 2017 at 9:26 PM, brenatlilydale@... [Losmandy_users] <Losmandy_users@...> wrote: John Seen this before in DEC and RA, repaired a DEC one not long ago (hope its not same one doubt it).. Unfortunately it's a bad DEC encoder IC. Yes there is a remote possibility its a DEC motor itself or DEC H bridge but I'm pretty sure its as I said. Upon switch on both motor pinions lock...aka they are applied drive voltages on both sides of their H bridges. Their pinions will have major resistance to movement and be difficult to turn (if you can and do it will log a boot fault in the HC). When you see the HC msg "system boot at xxxx....xx" the Ra pinion starts driving at sidereal rate., the DEC will stay locked resistant to movement and will only move if commanded. On the system I repaired that had the same symptoms and bad DEC encoder IC (above), the DEC pinion was weak and rotated slowly on pwr on and drove crazy if one of the HC DEC buttons was pressed. Both Ra/DEC motor encoder ICs U15/16 are firmware installed. Repairer: Rene? (Germany); David Partridge (UK); Michael Herman (USA); Me (Australia); Losmandy (USA)...anyone I miss? Brendan -- Michael Herman mobile: 408 421-1239 email: mherman346@... [Non-text portions of this message have been removed] |
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Re: Motor stalled.......
Losmandy no longer repair G1 L
Dave From: Losmandy_users@... [mailto:Losmandy_users@...] Sent: 09 October 2017 05:27 To: Losmandy_users@... Subject: [Losmandy_users] Re: Motor stalled....... John Seen this before in DEC and RA, repaired a DEC one not long ago (hope its not same one doubt it).. Unfortunately it's a bad DEC encoder IC. Yes there is a remote possibility its a DEC motor itself or DEC H bridge but I'm pretty sure its as I said. Upon switch on both motor pinions lock...aka they are applied drive voltages on both sides of their H bridges. Their pinions will have major resistance to movement and be difficult to turn (if you can and do it will log a boot fault in the HC). When you see the HC msg "system boot at xxxx....xx" the Ra pinion starts driving at sidereal rate., the DEC will stay locked resistant to movement and will only move if commanded. On the system I repaired that had the same symptoms and bad DEC encoder IC (above), the DEC pinion was weak and rotated slowly on pwr on and drove crazy if one of the HC DEC buttons was pressed. Both Ra/DEC motor encoder ICs U15/16 are firmware installed. Repairer: Rene? (Germany); David Partridge (UK); Michael Herman (USA); Me (Australia); Losmandy (USA)...anyone I miss? Brendan [Non-text portions of this message have been removed] |
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Re: Motor stalled.......
Most likely problem here is either the motor shaft encoder, followed by the quadrature decoder ICs.
I can fix either of these problems (I live in the UK) as I am sure can Michael Hermann (CA) and Bren Smith (Australia). Dave From: Losmandy_users@... [mailto:Losmandy_users@...] Sent: 09 October 2017 02:03 To: Losmandy_users@... Subject: [Losmandy_users] Motor stalled....... Hello all, New member here, with a problem. Ok, I just picked up a used G11 with Gemini 1 level 4 version 1.05. When trying to align to a bright star the dec motor show's motor stall. I figured something must be binding, so I took out the motor and tried it again, same thing, eliminating possible worm binding. After restarting the system I noticed that after putting the mount in sidereal rate the ra motor seems to spin at a that I would expect but the dec gear is spinning at a few hundred rpm not with enough torque to move the mount. Then when I try to align on the hand controller, it speeds up to a high rpm for a split second then shows the error. When turned off the motor turns by hand freely. The power supply that came with it is at 12v so I tried a higher voltage one at 14.5v, no different. Where do I start? Thanks John |
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Re: Motor stalled.......
If it is the U15 or U16 chip, then David Partridge in the UK has these or can make them. I have not yet tackled that.? These chips are in sockets on the main board and can easily be? pulled out (say with an automotive sharp hook tool) and replaced by the owner. If it is the motor's encoder element, then, again, I have no experience with that trouble.?? In either case, I am surprised the prior owner did not experience the problem and that John, who? just acquired the system, is stuck with this problem from his first experience.?? Best of luck, Michael On Sun, Oct 8, 2017 at 9:26 PM, brenatlilydale@... [Losmandy_users] <Losmandy_users@...> wrote:
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Re: Motor stalled.......
John
Seen this before in DEC and RA, repaired a DEC one not long ago (hope its not same one doubt it)..? Unfortunately it's a bad DEC encoder IC.?? Yes there is a remote possibility its a DEC motor itself or DEC H bridge but I'm pretty sure its as I said. Upon switch on both motor pinions lock...aka they are applied drive voltages on both sides of their H bridges.? Their pinions will have major resistance to movement and be difficult to turn (if you can and do it will log a boot fault in the HC).?? When you see the HC msg "system boot at xxxx....xx" the Ra pinion starts driving at sidereal rate., the DEC will stay locked resistant to movement and will only move if commanded. On the system I repaired that had the same symptoms and bad DEC encoder IC (above), the DEC pinion was weak and rotated slowly? on pwr on and drove crazy if one of the HC DEC buttons was pressed. Both Ra/DEC motor encoder ICs U15/16 are firmware installed.? Repairer: Rene? (Germany); David Partridge (UK); Michael Herman (USA); Me (Australia); Losmandy (USA)...anyone I miss? Brendan |
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Re: Motor stalled.......
¿ªÔÆÌåÓýHi John, ? I have just repaired a mount with exactly the same symptoms you describe. In my case, it was the encoder pickup in the back of the high torque servo motor that was faulty. Luckily the optical shaft encoder pickup was available from RS Components and was relatively easy to replace. ? Not sure if you have the same motors, but it would be worth checking. ? Regards Martin ? From: Losmandy_users@... [mailto:Losmandy_users@...]
Sent: 09 October 2017 03:03 AM To: Losmandy_users@... Subject: [Losmandy_users] Motor stalled....... ? ? Hello all, New member here, with a problem. ? ?
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Re: Motor stalled.......
hmmmm... a good puzzle.... Try this: set the Gemini to "terrestrial" tracking which means it will not drive RA or DEC.? ? If you do that, neither RA or DEC should move. If the Gemini is still driving the DEC, there is one possible cause: the handset serial cable, or the handset itself can have an intermittent contact in the diamond switch (North South butttons moves the DEC only).? ?Try removing the handset from its cable.? If the DEC stops moving, then it is a flaw or short in the handset.?? To remedy that, unscrew the 2 Phillips screws in back of the handset. Open the handset case.? Look for and clean any discoloration or residue on the ribbon cable or its connector, and on the circuit board, using a cotton swab dipped in alcohol.? Usually this clears up any slight surface short.?? Hope you get this cleaned up and enjoy your system... Best, Michael? On Oct 8, 2017 18:58, "mknwfhccabsgfi2b7fvsii57vq43ikvdv4r3sfuo@... [Losmandy_users]" <Losmandy_users@...> wrote:
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