STi Autoguider Problem

Discussion in 'STF Series CCD Cameras' started by Slewmaster, Dec 22, 2014.

  1. Slewmaster

    Slewmaster Cyanogen Customer

    Joined:
    Dec 22, 2014
    Messages:
    15
    After establishing a link using CCDOps5 the mount (CGEM-DX) starts moving RA+. Also, it is impossible to re-position the mount using the hand controller or an observatory program. Disconnecting the autoguider cable clears the problem, but then, autoguiding is not possible either. The STi is connected directly to the mount using a crossover autoguider cable. The mount has +5v pullup resistors on the input. Do I need to return the STi for repair or is there something else I have overlooked?
     
  2. Doug

    Doug Staff Member

    Joined:
    Sep 25, 2014
    Messages:
    9,932
    Are you using the autoguider cable provided with the ST-I? Also check the port definition and make sure it matches the definition in the ST-I manual.

    The reason I mention these two items is these cables can be assembled with the connectors in two different orientations. If it is wrong the autoguider port will be cross-wired, which tends to have all kinds of oddball consequences.
     
  3. Slewmaster

    Slewmaster Cyanogen Customer

    Joined:
    Dec 22, 2014
    Messages:
    15
    I am using the autoguider cable supplied with the ST-i and the port definitions are correct in the software.
    I'm thinking the ST-i autoguider port is defective because if I use MaximDL 6 in the Guide mode with the ST-i, I can not Move the mount. However, if I use a QSI CCD camera, I can Move the mount using MaximDL 6.
     
  4. Tim

    Tim Staff Member

    Joined:
    Sep 25, 2014
    Messages:
    1,841
    What is the "Autoguider Output" set to in MaxIm DL?

    Are you using the same ST-i guide cable with the QSI or a different one?

    If you are able...check the guide cable itself with a multi-meter.

    Check the guide port on the ST-i to ensure the connector pins are not shorted.
     
  5. Slewmaster

    Slewmaster Cyanogen Customer

    Joined:
    Dec 22, 2014
    Messages:
    15
    Guider output is set to 'Guider Relays' for both the ST-i and QSI camera configurations. I used the same autoguider cable on both cameras. I have checked the autoguider cable with a multimeter and the pins are not shorted. The pins in the RJ jack of the ST-i camera look good. I've measured the pullup voltage on the mount without a camera connected and the voltage is +5.01 vdc on all 4 control pins. With the QSI camera connected the voltage is +5.01 vdc on all 4 control pins. With the ST-i camera connected the voltage drops to +3.47 vdc on all 4 control pins.
     
  6. Jan Soldan

    Jan Soldan Cyanogen Customer

    Joined:
    Oct 11, 2014
    Messages:
    239
    Location:
    Czech Republic
    I am not sure, but maybe you should power your ST-i from the powered USB hub, if not already done.
    The ST-i consumes nearly 500 ms, so USB port of your computer need not provide enough power.
    Jan
     
  7. Doug

    Doug Staff Member

    Joined:
    Sep 25, 2014
    Messages:
    9,932
    That's very odd about the +3.47 VDC. It sounds like it's pulling them down to 3.3V, but that's not possible given the schematic design. It's fully opto-isolated.

    Please try Jan's suggestion of powering the device through a powered USB hub. It may be that the camera is not fully powered up.
     
  8. Slewmaster

    Slewmaster Cyanogen Customer

    Joined:
    Dec 22, 2014
    Messages:
    15
    Using a USB powered hub does not solve the problem. The ST-i works great in all other aspects. Since the +5 VDC that is being sourced by the mount through a pull-up resistor is being pulled down to +3.47VDC when the ST-i is connected to the mount makes me suspect the ST-i port has a failure of some nature. All four control lines are pulled down from +5 to +3.47 VDC. I don't see the voltage pull-down behavior when I use the QSI autoguider port. Could the opto-isolated port be defective?
     
  9. Doug

    Doug Staff Member

    Joined:
    Sep 25, 2014
    Messages:
    9,932
    I've reviewed the schematic and it seems very unlikely, but I obviously can't rule it out entirely. I would think if the optoisolator failed it would either be open circuit or shorted. Limiting the voltage seems unlikely.

    Are you certain there isn't an issue with the cable?
     
  10. Slewmaster

    Slewmaster Cyanogen Customer

    Joined:
    Dec 22, 2014
    Messages:
    15
    I have 2 types of cables. One is straight thru and the other is crossed over. One of the cables is used with Orion and Celestron cameras. The other cable is used with ST-i and QSI cameras. The cable for the QSI camera works okay with the QSI camera but does not work with the ST-i camera. I have used a multimeter on both cables to identify shorts and opens and both cables are okay. I will re-check the cables and cameras again today and get back to this afternoon with the results.
     
  11. Slewmaster

    Slewmaster Cyanogen Customer

    Joined:
    Dec 22, 2014
    Messages:
    15
    Much to my surprise, the ST-i guider port is now working, but I don't know why. I haven't changed any cables, etc. I've tested it numerous times since Tuesday under differing temperatures and it hasn't failed yet which makes me wonder why it was failing before Christmas. Intermittent problems can be difficult to resolve. Thank you for helping me with this issue......I hope it doesn't come back.....but it most likely will at the worst possible time (Murphy's Law). Thanks again for your help.
     
  12. Slewmaster

    Slewmaster Cyanogen Customer

    Joined:
    Dec 22, 2014
    Messages:
    15
    Well the problem came back (no surprise) but after more troubleshooting the problem turned out to be an elusive ground loop in my power distribution setup. The ground loop was causing power fluxuations. All is working okay now. Thanks for the support.
     
  13. Doug

    Doug Staff Member

    Joined:
    Sep 25, 2014
    Messages:
    9,932
    Now that makes total sense. Glad you figured it out.
     

Share This Page