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"big" ursa 4k magenta screen of death?

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  • #16
    I rooting for you to succeed in your efforts to get your URSA running again.

    While you're at it, seeing as you've torn it down very extensively. Can you ( if you haven't already ) document in some finer detail the entire/construction/assembly/components/pcb of the camera?

    Pictures of PCB in High res, with good lighting ( to show the IC marking, etc... ) The sensor block, etc.. cooling system.

    The pictures you've posted so far aren't the greatest quality, hard to read any detailed information on any of the PCB.

    You can add to the existing thread I have here:
    ( looks like you were already posting about your URSA there )

    I'm sure it would serve well to those interested in the topic, even if just for pure academic purposes.


    • #17

      Except for film stills camera, I don't have anything with better resolution than the picturephone. There is a DoP freind who has a 7D. I might get him to take some happy snaps of the post-mortem for that is what it now is. A tiny 1mm x 4mm conductive pad on the motherboard must have roasted off with the heat of desoldering the supercapacitor which was thought to be a coin battery. If BM was not so secretive, I would not have gone after a failed memory battery and instead left the supercapacitor where it was. The pad rose up a little and became detached. The little piece does not appear to have any connection to surface tracks on the PCB so I would have epxected it to be connected to other layers by feedthrough conductors. There are no signs of feedthroughs into the circuit boards below it so I have no idea how the current travels from the capacitor -ve to anywhere else. If there are feed-throughs in the PCB to other layers they must be spiderweb thin. How to install a replacement supercapacitor is going to be the challenge if at all possible. The system still switches on and the image displays are the same as before. A chill spray over the board and components and dry-off changes the behaviour of the faint pixellation pattern which becomes very sightly more apparent. Like other tests, the pattern goes away on subsequent startups, maybe due to temperatures reaching an operating range. The device cannot be operated for more than a few seconds because I have no heatsinking on the Xilinx processors and they will be damaged if I power up for longer.


      • #18
        For what it's worth, I did also have an old BMPCC go bad, to the point where the sensor output was similar to what I think you're experiencing.

        I had a bad power button on the BMPCC ( among other things like a broken HDMI port ) which meant I had to disassemble the camera and make repairs a few times.
        In the process of doing that, I believe I imposed too much stress/bend on the sensor flex cable that is bonded between the sensor board and the main PCB.

        Upon re-assembling it the last time I did this was the image output I was greeted with...


        The explanation I got from BMD was that this is caused ( most-likely ) by a fault/damage to the sensor connection.
        Which totally lines up with what was happening over the numerous times I was in and out of the camera.

        So I'm not sure your diagnosis of the super-capacitor as the culprit of your problem is necessarily the right one.
        Obviously lots could be at play, but I'm going to draw some similarities between these two and say It's an issue with the sensor connection ( possible damage to it. )
        and/or any sub-systems associated with it.


        • #19
          Yes. That is near-identical to the screens on the big URSA. - Dead and buried then at a guess. The ribbon cables are sandwiched between the multilayered PCBs on the turret and the motherboard. There are no obvious test points one can use to check continuity across the in-line slot plug. One would have to be really careful when checking at other points on the boards. Without info from BM that cannot happen systematically. Time for crying in one's cups or dropping down on the ground in a rage and kicking up dust.


          • #20
            Further to above, the phantom power and external mic inputs work and the travelling waveform on the controller screen displays correctly.


            • #21
              It has been a while since I posted here. I was unable to do so and gave up. I have just discovered the site is working again.

              The sequel to the whole dead URSA affair which I discussed on the BM forums was that I found another :big" URSA on eBay which was a non-starter. I took a punt on the turret being okay and it turned out to be good. So I caused an unholy matrimony between the two and one complete camera is the result. The sensor must also be a later version because the purple sun artifact has gone. Unfortunately the supercapacitor being out means the camera reverts to its original birthday after each shutdown. The recorded files shuffle in order according to time and day after the birthday they were shot. The SI2K also does this when the memory battery goes flat. I sourced some replacements but given the camera otherwise works fine, I am not inclined to pull the whole thing apart and risk killing it off completely.

              This was its most recent outing. The focus is a bit off. I had only just the night before managed to re-assemble the zoom lens which had been fungussed and needed cleaning. The focus ring was a bit stiff and with the zoom and heavy weight of high tilts, I was not getting it right much of the time.