GPINTCheck indicates movement in Dec, but not RA

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Rich
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Joined: Thu Sep 13, 2007 10:37 pm

GPINTCheck indicates movement in Dec, but not RA

Post by Rich » Sun Oct 09, 2016 9:03 pm

After a lapse of several years, I'm returning to astrophotography. I'd planned to dedicate a Windows XP Dell laptop to guiding my Losmandy G-11 (non-Gemini) mount, using the LPT port, GPINT-PT, and the cable (pin 1 to pin 1, etc.) that I bought from Shoestring Astronomy several years ago.

Before using GPINTCheck to make sure my setup works, I confirmed that there were no problems with my LPT port. Indeed, Windows XP's Device Manager detected a problem-free LPT1 port.

Although Device Manager "sees" only one LPT port, GPINTCheck sees three:

( ) LPT1: 38C
(•) LPT2: 378
( ) LPT3: 278

I tested RA and Dec by clicking each of GPINTCheck's red test buttons while pressing my ear to the RA and Dec motors to listen for changes in each motor's sound. I encountered two anomalies:

--Only with LPT2 selected did I hear any difference in the sound (Dec motor only).
--And with LPT2 selected I could hear changes only when I pressed Dec+ or Dec-. Apparently neither RA+ or RA- signals are getting to the RA motor.

Are there any settings I can change to get the RA motor to respond? And why is GPINTCheck telling me I'm connected to an LPT2 port when Device Manager sees only an LPT1 port?

Many thanks for any help you can provide.

dpanderson
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Re: GPINTCheck indicates movement in Dec, but not RA

Post by dpanderson » Mon Oct 10, 2016 6:14 pm

Rich,

I am not sure what is happening with LPT2 vs LPT1. I no longer have a PC with a parallel port, so this part of it will be impossible for me to comment on.

If you have a multimeter, you can check the health of your GPINT in a manner similar to what is discussed for GPUSB in this forum post:
viewtopic.php?f=3&t=98

Please let me know if this sheds any light on the problem.
Doug Anderson
Shoestring Astronomy
http://www.ShoestringAstronomy.com

Rich
Posts: 4
Joined: Thu Sep 13, 2007 10:37 pm

Re: GPINTCheck indicates movement in Dec, but not RA

Post by Rich » Sun Oct 16, 2016 10:49 am

Looks like I'm OK, Doug. The high/low voltage tests showed what they should have: either 3.7 vdc or 0.6 vdc as I checked the pins in the sequence shown in the link you provided. I also tried another ear-pressed-to-the-motors test. This time I did detect an audible difference when the RA+ and RA- buttons are clicked in GPINTCheck. The sounds change differently in RA than in Dec. In RA+ there was a subtle speeding up of the motor. In RA- there was a subtle decrease in the motor's speed. Those are different sounds altogether from the on/off sounds I heard when I tested the Dec motor.

Thanks very much for jumping in to help me with the older technology I'm using. I'd love to buy a GPUSB, but as a retired person I tend to fix the old, rather than buy the new. :)

dpanderson
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Re: GPINTCheck indicates movement in Dec, but not RA

Post by dpanderson » Sun Oct 16, 2016 4:33 pm

Glad to hear it is working.

Enjoy!
Doug Anderson
Shoestring Astronomy
http://www.ShoestringAstronomy.com

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