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Hi Michael, folks...Q & A....

yes the the U15/16 PLD ICs are indeed the "16V8BQL" (note "BQL") low power devices.?? I would not use the higher pwr devices for example the "BQ" version uses double the current draw when active and 7 times more in standby.? The "B" device is even worse.? See data sheets.

U15 is the Ra motor encoder IC it is the lower one if viewing the PCB north/south.?? U16 "DEC" is the upper one.

These PLD encoder ICs fail mainly when plugged in the DIN sockets.?? You can miss-orientate this DIN easily even though it has a "key".? This can put +12V onto the encoder lines which damages them.? Losmandy tried varistors and other small things (Transorbs I think)on the PCBs in mitigation but nothing works.?

I'd? like to see failure data rates of older "RJ" PCBs compared to the "DIN" PCBs to see indeed if there is a difference.? Although I can confirm more than one user who has sent me a PCB admitted they misaligned the DIN.

Mostly this is at night or in darker conditions.? Tom/Paul?Rene/Me (and others) have been warning of this for a long time.?? Its just the DINs were chosen for availability, price, reasons I am not privilege to.? But make no mistake plugging the Ra/DEC? motor leads incorrectly with pwr on can and will damage these ICs.

David....I always thought the motor encoders were US Digital...I just looked at an old one...its actual fact HEDS 9000 series "Broadcom".? I'll check this later today I've obviously had this wrong for some time.? I have replaced one motor encoder inside a motor.? But this was a Maxon motor...soooo nice...and smooth worth fixing.

The U11/12 PIC 17C4X Ra/DEC processors rarely fail.? In fact I've never seen one.? I once repaired a PCB that had almost all major ICs dead but not these....I mean how does that happen?

So folks..."Never try to plug/un-plug your motor DIN connectors with power on in the dark"!

Brendan


?

Hi,

Thanks a lot Chip. That's pretty much the answer I was hoping for
I haven't used it that much really so I hope it will keep on going as it previously has. Otherwise I guess I'll have to upgrade some of the parts since it is really quite old now.

Hi Fredrik,

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]

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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Micheal, I will call you this evening.

John

--

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!

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

Not sure what you mean?? Do you need a number off the board? Did not get this from Losmandy.

John

The PCB ident is under the ICs.

Did you get this from Losmandy?

Brendan

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

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]

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]

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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