Connecting GPUSB to Losmandy G9 Mount

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stott100
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Connecting GPUSB to Losmandy G9 Mount

Post by stott100 » Tue Apr 23, 2019 11:35 pm

Hi,

I have just purchased a GPUSB guide adapter and cable for my non-Gemini Losmandy G9 mount (made for Celestron). When I plugged it in there was a short circuit which blew up a diode (reverse polarity protection) in the Celestron Digital Drive System Model 492. I have replaced the diode and the 492 is still working and tracking but I am reluctant to connect the GPUSB again.

I read the information on the information published by Shoestring on the correct GPUSB for the Losmandy mount, so just want to confirm that the GPUSB model will work with my mount which has a HCC/CCD socket on the 492 for the hand controller. The hand controller just has buttons which open and close contacts. So how does the GPUSB mimick the opening and closing of contacts?

Not sure if the GPUSB has been damaged but can I return it for replacement in case it is?

It was shipped on 30/3/19 to Australia and received a week or so later.

Description Unit price Qty Amount
USB Guide Port Interface (guide port cable not included)
Item# GPUSB $75.00 USD 1 $75.00 USD
Subtotal $75.00 USD
Shipping and handling $17.00 USD
Total $92.00 USD
Payment $92.00 USD

Thanks Dallas

stott100
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Re: Connecting GPUSB to Losmandy G9 Mount

Post by stott100 » Wed Apr 24, 2019 7:39 am

Further to my question:

The wiring diagram for the HC/CCD port on the Celestron Digital Drive System Model 492 is shown in this thread:

https://www.cloudynights.com/topic/4427 ... oUjuxnj6_Q

The note on the Shoestring webpage about Losmandy mounts reads as follows:

"NOTE to Losmandy Owners: If you have a GM-8 or G-11 without the Gemini box, you will need the GPUSB or GPINT-PT. If you are using the NEW style Gemini box (the NEW style has a circular DIN connector to connect to the motors), then you will need the GPUSB or GPINT-PT. If you are using the OLD style Gemini box (the OLD style has a modular RJ-45 connector to connect to the motors), then you will need the GPUSB-AH."

My mount is a Losmandy G-9 made for Celestron (without the Gemini Box).

Thanks Dallas.

stott100
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Re: Connecting GPUSB to Losmandy G9 Mount

Post by stott100 » Wed Apr 24, 2019 7:48 am

Hi Again,

Here is are photos of the Celestron Digital Drive System Model 492 and the wiring diagram for the hand paddle that plugs into the HC/CCD port.

Thanks Dallas.
Attachments
Celestron Digital Drive System Model 492.jpg
Celestron Digital Drive System Model 492.jpg (102.49 KiB) Viewed 232 times
Celestron Digital Drive System Model 492 Wiring Diagram.jpg
Celestron Digital Drive System Model 492 Wiring Diagram.jpg (196.81 KiB) Viewed 232 times

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Re: Connecting GPUSB to Losmandy G9 Mount

Post by dpanderson » Sat Apr 27, 2019 6:18 pm

From the diagram you provided, if the direction of the LED in the diagram is correct, then the 492 has an "active-high" configuration, which would explain why you had the failure. If true, you need the GPUSB-AH, not the GPUSB.

Do you have a voltmeter? If so, attach the positive lead to pin 2 of the on the 492 box and the negative lead to pin 1. If the voltage reads positive, you do have an active-high configuration. If the voltage reads negative, then it is active-low and the GPUSB should have worked. If it reads no voltage, then from the diagram I don't see how the red LED could possibly light up.
Doug Anderson
Shoestring Astronomy
http://www.ShoestringAstronomy.com

stott100
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Re: Connecting GPUSB to Losmandy G9 Mount

Post by stott100 » Mon Apr 29, 2019 11:13 pm

Hi Doug,

I checked the voltage and the Model 492 Celestron Digital Drive System does indeed have an "active high" configuration so I need the GPUSB-AH.

Can I swap my GPUSB for a GPUSB-AH?

It was shipped on 30/3/19 to Australia and received a week or so later.

Description Unit price Qty Amount
USB Guide Port Interface (guide port cable not included)
Item# GPUSB $75.00 USD 1 $75.00 USD
Subtotal $75.00 USD
Shipping and handling $17.00 USD
Total $92.00 USD
Payment $92.00 USD

The GPUSB came with a guide port cable (which the above information says is not included) so do I need to return the cable as well?

Do I need to return the GPUSB to the USA or can I return it to Bintel in Australia?

Bintel do not list the GPUSB-AH but they may be able to order it from the USA.

https://www.bintel.com.au/product/shoes ... c98ba2045f

Also please note that the information on the Shoestring webpage to Losmandy Owners (see below) is misleading as I ordered the GPUSB because I have the G-9 mount (similar to GM-8) without the Gemini Box:

"NOTE to Losmandy Owners: If you have a GM-8 or G-11 without the Gemini box, you will need the GPUSB or GPINT-PT. If you are using the NEW style Gemini box (the NEW style has a circular DIN connector to connect to the motors), then you will need the GPUSB or GPINT-PT. If you are using the OLD style Gemini box (the OLD style has a modular RJ-45 connector to connect to the motors), then you will need the GPUSB-AH."

Many thanks

Dallas Stott

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Re: Connecting GPUSB to Losmandy G9 Mount

Post by dpanderson » Wed May 01, 2019 9:02 am

I'd say it is quite likely that the output drivers on your GPUSB are now damaged, but the good news is that this is the part that is different between a GPUSB and a GPUSB-AH. So, I think the best course of action is to return it to me and I will repair/convert it to a GPUSB-AH. I'll send you a private message with more information.

Thanks for the information regarding the note on our website and your GM-9. I'm not sure how one would be able to tell the difference other than doing the voltmeter measurement, so maybe that is the warning I should put on the website. I've contacted Losmandy in the past to try and get a better understanding of which models are active-high, but they have never replied.
Doug Anderson
Shoestring Astronomy
http://www.ShoestringAstronomy.com

stott100
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Re: Connecting GPUSB to Losmandy G9 Mount

Post by stott100 » Thu May 02, 2019 9:08 am

Hi Doug,

It seems strange that the G-9 mount is active high (need GPUSB-AH) whereas the G-8 and GM-11 are active low (need GPUSB) as I understand the G-9 is a copy of the G-8 made for Celestron.

So yes maybe the voltmeter measurement is the warning you should put on the website.

I would like to return my GPUSB to you for repair ASAP as I note you are closed during June/July, I assume for the school holidays (three of my grandchildren live in Boulder CO).

Please provide further details so I can send it in the next couple of days as international express post is expensive from Australia.

Many thanks,

Dallas Stott

stott100
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Re: Connecting GPUSB to Losmandy G9 Mount

Post by stott100 » Sun May 05, 2019 6:49 am

Hi Doug,

I have posted my GPUSB for repair and conversion to a GPUSB-AH two days ago as confirmed in my PM to you.

I confirm the Celestron Digital Drive System Model 492 for my G-9 mount (made by Losmandy for Celestron) is configured active high.

When I press the buttons on the my Celestron hand controller, the outputs are raised from zero to positive 8.5 volts DC (12.27 volt DC power supply).

Is this voltage compatible with the GPUSB-AH inputs?

Also can I safely run the Celestron hand controller in parallel with the GPUSB-AH using this guide port splitter?

http://www.store.shoestringastronomy.com/gpspl.htm

Many thanks,

Dallas Stott

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Re: Connecting GPUSB to Losmandy G9 Mount

Post by dpanderson » Fri May 31, 2019 8:07 am

Dallas,

Apologies for the slow reply, I just noticed this post today.

The voltage should not be an issue.

I believe the handcontroller should be able to run in parallel.
Doug Anderson
Shoestring Astronomy
http://www.ShoestringAstronomy.com

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