Staff Assigned: Tim Unreliable Connection

Discussion in 'STF Series' started by Aleh, Feb 7, 2020.

  1. Aleh

    Aleh Standard User

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    Hello.
    I am not sure about writing to this place, but I try.
    My STF 8300m connected to my laptop by "active" USB cable 5m.
    All other stuff (mount, focuser, guiding camera etc.) connected to D-Link USB Hub (7 ports) and then connected to another usb port of my laptop by the same active USB cable 5m.
    I use this configuration some years without any problems.
    But after some months without clear sky, some days ago I turned on all hardware, connected as usual to laptop and ooops - Windows 7 64 couldn't recognize cable with 8300. Another stuff is ok. I changed my active cables, but result the same - camera did not recognize. I said "bad news" and tried connect camera without active 5m USB cable, but just 3m usb "passive" cable . Ooops - works fine. I installed camera's driver to my desktop PC and tried connection with active 5m cable. Works fine!!! (Windows 7 64 too) o_Oo_Oo_O
    So, I have good camera, 2 good 5m active cables, good laptop's usb ports, everything works fine, but I can't connect my camera by 5m active cable, what absolutely I need! And it was ok 3-4 years!
    Please, any advises?
    P.S. I tried to remove and reinstall SBIG 64-Bit Driver Checker. I wrote last firmware to my camera. Nothing changed.
     
    Last edited: Feb 7, 2020
  2. Tim

    Tim Staff Member

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    Does the camera show up under the Windows Device Manager when you plug it in, but cant connect with the active 5m cable?

    Active USB cables are of varying quality, generally unreliable for this purpose, and may not work well in the cold. A 5m passive USB cable is the absolute maximum length of unpowered USB communications. If you are using that length of cable, you should ensure it is absolutely the highest quality shielded cable you can obtain, though even then, it may have communications issues as you have discovered. If a shorter cable works but the longer one doesn't, there is not much you can do about it other than use the shorter cable, or move the PC closer. Also try a different USB port.

    -Try a high quality shielded USB cable
    -Use a shorter cable
    -Try a different USB port

    Re-installing the drivers will not help improve USB communications. The drivers either work, or they don't, and from your description, they appear to be working fine. I would say the problem is with the cable.
     
  3. Aleh

    Aleh Standard User

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    Thank you for your answer, Tim.
    No, with active cable connection with my laptop, Windows can not recognize the camera and connect-disconnect every second. But with desktop PC all works fine!
    Of course, but I have two different, both of them worked some years with my setup and works fine with other my hardware and the camera WORKS with both of them connected to desktop PC!
    Thank you, I know this, so I doesn't use 5m passive USB cable.
    It's not possible, I need minimum 5m.
    As I wrote above, I tried.
     
  4. Colin Haig

    Colin Haig Staff Member

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    One more suggestion - use an AC-powered USB 2.0 hub between the computer and active cable
     
  5. Aleh

    Aleh Standard User

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    Thank you, I use exactly this configuration with the second 5m active cable. As I wrote, all my hardware (but 8300 camera) connected to hub (yes, it is AC-powered usb 2.0 hub) and the hub connected to laptop by 5m active cable.
    The first time I tried connect ALL to this hub and then to laptop by active cable, but sometime I received Error (8), so
    I connected the camera with her own separate active cable and it worked great year by year.
    But ok, I will try connect the camera through the hub.
     
  6. Aleh

    Aleh Standard User

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    I disconnected all hardware from the hub and connect the camera only.
    Camera - Hub - active cable 5m - laptop.
    Ooops - Windows take the camera ok and I see it in Device manager.
    CCDOps and Maxim DL connect the camera without problem.
    BUT :( After 5-10 shots I see "Camera error (8)".
    It seems that some parameters in the USB part of the camera have deteriorated
    over time and now the signal parameters are insufficient for the previous operation :(
     
  7. Doug

    Doug Staff Member

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    I've never heard of the "USB part of the camera" degrading in such a fashion. There's basically a USB chip, simple filter and ESD protection, and the connector. There's really not much that can go wrong in a way that would degrade performance, rather than stop it from working altogether. They tend either work or not.

    About the only thing that could cause signal degradation would be corrosion caused by water in the camera. That could possibly degrade the circuit board itself. You might want to have a close look at the camera and make sure it isn't water damaged.

    USB signals can be degraded by impedance mismatches. A bad cable will cause that. Using the front USB connectors on a desktop computer can do that (they typically have pretty crappy wiring inside - use the rear connectors because they're right on the circuit board). Hubs are also a common problem, including active cables because they're just a cable with a one-port hub built in.

    Most hubs do not work well in cold conditions, e.g. freezing or below. They go off frequency and communications become very unreliable. If you experience cold temperatures you will need an industrial-quality hub.
     
  8. Aleh

    Aleh Standard User

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    All you said is true. But, on other side, my camera never worked good with hub, so I use direct connection from the camera to laptop by active 5m cable. This configuration worked great for me some years in summer and winter (mostly at the balcony).
    And now:
    1. The camera is ok (?) it works with 3m usb cable with laptop without any errors.
    2. 5m active cable is ok, all other hardware connected to AC-powered hub and then by this cable to laptop and works good. The camera, connected by this 5m active cable to desktop PC works fine too (!!!).
    3. Laptop is ok too, all equipment is working fine anyway.

    I find it difficult to tie it all together and find the right conclusions. :confused:

    After all I opened the camera from bottom side.
    I do not see any problems with humidity or something similar on the board.
     

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    Last edited: Feb 8, 2020
  9. Doug

    Doug Staff Member

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    It looks pristine. I really don't think you have a camera issue.

    I suspect the problems have something to do with the cabling / extender / hubs.

    Cables do vary in their impedance; better quality cables are often closer to spec, but they all vary a little - or a lot. The further off target they are the more reflections you get and more signal degradation. Sometimes simply using a different cable makes a huge difference.

    So... find a combination that works, label them, and stick with it!
     
    Aleh likes this.
  10. Aleh

    Aleh Standard User

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    Bad news after all.
    Today I tried different combinations cables and hubs, but at last I connected camera by 3m cable only and found slow downloading of images. Instead ~1sec as it was always before, now full image (bias, dark, light - no difference) downloads about 8sec. Bin 4x4 image downloads ~5sec.
    In TDI mode after pressing "Expose" button I see "Camera error (6)" message. TDI mode was OK yesterday. :(

    Updated. After some attempts TDI mode is OK. But download speed is not ok.
     
    Last edited: Feb 9, 2020
  11. Aleh

    Aleh Standard User

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    Is there any service manual for this camera? Not a detailed diagram with a description
    (that would be too good), but at least a brief guide - check the voltage at these points,
    look at the waveforms in these, should they be such and such, etc.? Or do I want something unrealizable?
    Thanks.
     
  12. Doug

    Doug Staff Member

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    The camera is not user serviceable.

    Also measuring voltages is not going to tell you anything. If the voltages were incorrect the camera would not work properly at all.

    Honestly I do not think there is anything wrong with your camera.
     
  13. Aleh

    Aleh Standard User

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    Everything is serviceable. :)
    It depends on the nature of the malfunction. A competent user could fix many problems on his own.
    Here are two waveforms on the line of the D- USB path. The first is the connected ASI178mm camera.
    The second is signals from my STF-8300mm. Therefore, I am sure that the camera is not in order.
    But given the cost of repairing and shipping it to the United States and back - it does not make economic sense.
    Therefore, either I can fix it myself, or it will die.
     

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  14. Doug

    Doug Staff Member

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    Uh... your scope is set to 1 microsecond per division.

    USB 2.0 speeds are 480 megabits per second. That's about 2 nanoseconds per bit. Your scope is nowhere near fast enough to record USB 2.0 signals. In fact a 1 gigasample/second oscilloscope isn't fast enough.

    What you're seeing on the ASI camera is consistent with USB 1.0 Low Speed @ 1.5 megabits per second. If that's a USB 3.0 camera then you're looking at the wrong data lines. The high speed lines are 5 gigabits per second.
     
  15. Aleh

    Aleh Standard User

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    Perhaps this is not directly USB data. Maybe this is some kind of synchronization signal or something similar, I have not yet figured out in detail the data structure on the USB bus. But I know for sure that such an oscillatory waveform is abnormal for a digital device. And I can compare similar signals from two different cameras.
     
  16. Doug

    Doug Staff Member

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    You can't look at the USB 2.0 databus with a slow speed oscilloscope. It will not tell you anything. Simply putting the probe on there will disturb the signals.
     
  17. Aleh

    Aleh Standard User

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    Hello again.
    Could you help me with these element—č 1 and 2? There are no signs on the board or on the elements themselves.
    Suppression diodes? Varistors? ...?
    This back of the board is under the USB socket.
    Thank you.
     

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    Last edited: Feb 16, 2020
  18. Doug

    Doug Staff Member

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    The differential USB data lines are on the other side of the connector - you aren't even looking at the data lines.

    The equipment you have is not capable of analyzing a USB 2.0 interface. You would need a bandwidth of at least 2 GHz and sample rate of at least 5 gigasamples per second. We're talking about a $20,000 instrument - at the low end!

    If the USB interface was damaged it simply would not work, period. There is nothing you can fix. You are merely running the risk of damaging the camera.

    We can assume no responsibility for customer-induced damage. As such we will not answer any further technical questions about the internals.
     
    Last edited: Feb 16, 2020
  19. Aleh

    Aleh Standard User

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    I know it. I'm just trying to determine the reason for the slowdown of the USB interface and now it seems to me that the reason is the degradation of some details of the USB line protection circuit. Perhaps these are elements 1,2 and (or) D6.
    This is a fair position.
    But this position is not entirely clear to me. I do not ask you for a schematic diagram, verification protocols and other service information. I just ask for human help in some minor issues that obviously do not affect your commercial or other interests.
    What does it matter to me if it still doesn't work fine anyway?

    Thank you for your help.
     
  20. Doug

    Doug Staff Member

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    Highly unlikely. There is a transorb and a ferrite between ground and case. Also between USB power and case. USB power is only used to detect presence of the cable.

    The reason I do not want to answer technical questions is twofold. First I don't condone customer-performed service, and do not want to possibly depicted as encouraging it by answering your questions and thus assuming some liability for it (or to be used as a precedent by someone else). Secondly it is time-consuming and I do not believe it will be fruitful.
     

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