Staff Assigned: Tim Filter wheel errors, misalignment - STX FW7 on STX-16803

Discussion in 'STX and STXL Series Cameras' started by sixburg, May 13, 2017.

  1. sixburg

    sixburg Cyanogen Customer

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    I'm working with a new (3 mos) filter wheel which seems to be failing.

    The issue: it fails to go to filter positions accurately. When testing / exercising the FW in CCDOPS I get the error:

    "CFW Error
    Error occurred in the Query State
    CFW Cal Error"


    I've not found any reference to this error nor any information to solve it. The Cal Error caught my attention, but evidently and STX FW7 does not require calibration.

    I only used CCDOPs to see if it behaved the same as Maxim (ie, bad positioning). The FW is inconsistent with both programs. Sometimes it hits and other time it doesn't.

    The is my 2nd FW and they both exhibited this behavior. The one in question is new. The other one is about 1 year old and has just returned from repair. Is there something unusual about these devices or something unusual about my installation?

    I notice this most often when taking flats. Even now the FW is taking flats and working well after I moved the scope around a bit, connected and disconnected to two different programs...now the filter is centered.

    Something VERY STRANGE is happening. Insights welcome.

    Maxim 6.13 - Updated
    STX-16803
    FW7
     
  2. Doug

    Doug Staff Member

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    What is the serial number on your wheel?

    Did you remove the carousel when installing on the camera? We actually advise against this, because if you don't reassemble it properly it can cause problems.

    If you pull the driver motor shaft away from the edge of the wheel, does it spin freely? Does it stay in position if you lightly push down on it (there's a spring but it should take a fair bit of pressure to move it)?
     
  3. sixburg

    sixburg Cyanogen Customer

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    Hi Doug....
    Since your last post I've tried to find some level of repeatability--I have not. The FW fails apparently randomly.

    I don't know the serial number since it's not near me. How is this relevant? It was purchased new in the last 3 months. We did not remove the carousel...just installed the filters. This is the 2nd STX FW7 to go along with the 3rd STX-16803. Starting to remind of of Mrs. Black in The Rainmaker--you remember.

    I haven't performed the tests you've suggested because the system is remote. In addition, every disassembly of the image train causes major disruptions (slightly different rotation when reassembling requires manual updates to the entire ACP Scheduler database).

    I'll have access to the system over the weekend. Can you give more explicit information, suggestions or tests? What you've asked me to check has no action. If the wheel doesn't spin freely, then what? If it stays in position while lightly pushing on it, then what?

    Thank you,
    -Lloyd
     
  4. sixburg

    sixburg Cyanogen Customer

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    161104 = serial number

    The FW does not spin 100% freely when the motor driver is pulled away. The optical sensor is in contact with the FW and is leaving a white residue all along the circumference of the FW. It appears the sensor is riding too low or the FW too high. Yes, the center screws are snug and the FW is flush to the center spindle.

    I assume the contact is not normal??

    Additionally, there is a slight bump on the edge of the FW so the thin outer edge is not perfectly smooth.
     
  5. Tim

    Tim Staff Member

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    No, contact is not normal.

    If the optical sensor is touching the wheel, then I would thing the carousel is not actually sitting properly. The optical sensor can't really be adjusted height wise, so my feeling is the carousel is not actually flush. When you spin the carousel, does it appear to wobble?
     
  6. sixburg

    sixburg Cyanogen Customer

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    Hi Tim:

    I too would think it is not actually sitting properly, but it is as flush as it can be. I actually said in my post that the FW is "flush to the center spindle". It's a pretty simple thing...there are 3 screws in the center. The carousel is completely flush to that and the three screws are snug and offered no unusual resistance when being installed. Let's assume that I understand this at a basic level. Perhaps the spindle is not installed properly? I've never removed one so I've no idea.

    Here's what I do know:
    1. There is sensor to FW contact as stated earlier.
    2. The FW is warped - see video
    3. The edge of the FW has a burr - see photo
    4. The FW does not wobble per se (see #2)
    View photos and video here: https://www.dropbox.com/sh/qprax3edaob8inb/AAByVij4YpUa-jAsm35LDZI1a?dl=0

    I would like a replacement that has undergone a closer QC check.

    Thanks,
    -Lloyd
     
    Last edited: May 29, 2017
  7. Tim

    Tim Staff Member

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    I suspect it is the center spindle assembly (bearings, bellville washers, shims, base plate) of the carousel that is not sitting properly, not the actual wheel. The center shoulder screw sits in a recess in the base of the filter wheel. If the shoulder screw is not seated precisely in the recess for the shoulder screw, it will not sit flat, and the wheel will wobble. The fact that the optical sensor is scraping in your video tells me the wheel is not sitting flat.

    *ALL* filter wheels undergo stress testing, and QA. Each wheel is exercised 100+ moves before shipping and checked for contact between the filter wheel and optical sensors. Given this fact, I find it very unusual that you would experience this issue, especially with a second wheel having the same problem, and you say you have not removed the wheel, I have no explanations. Could you check the center shoulder screw?
     
  8. sixburg

    sixburg Cyanogen Customer

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    Agreed, it is not sitting flat.

    Point of clarification: There is no second filter wheel having the same problem. This is 2 of 2 filter wheels I have purchase. The first one would not reliably align the filter. Bill repaired this. While this repair was happening I purchased the one in the video. The problem it's having is different.

    It is important that we are clear on the chronology. The new (2nd) FW arrived, filters were installed, nothing removed and it operated normally for a while. Then, it began to throw "Filter wheel errors", or it would be in a constant state of "waiting for filter wheel". I opened it yesterday as per Doug's instructions and found all you see in the photographs. All the residue, scraping, etc. is as I received it the first time. It's a wonder it worked any at all.

    I understand that you do QC. This one arrived is defective. Perhaps something in shipping...no way for me to know.

    Your post offers no specific direction, recourse, solution, instruction, etc. Are you suggesting I disassemble once again and somehow "precisely" center the shoulder screw?

    Thanks,
    Lloyd
     
  9. Tim

    Tim Staff Member

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    Not necessarily *disassemble* the whole thing, but the center shoulder screw in the carousel needs to be checked/re-installed. These have occasionally been loosened by vibration during shipping, so I recommend you check it. Due to this occasional issue of shipping vibration, we now insert foam packing material inside the filter wheel during shipping. It may be possible you received a wheel that was manufactured and shipped before we started inserting foam a few months ago.

    See attached video for steps to re-install the bearings and carousel if you wish to try it. Otherwise, I can issue you an RMA to send it back, and we can have a look at it.

    https://www.dropbox.com/s/nbwxccl3j7bfr5z/MVI_0875.MOV?dl=0
     
  10. sixburg

    sixburg Cyanogen Customer

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    Thanks, Tim. Very helpful!
     

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