Opinions on laser theory, please

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  • blackcat4866
    Master Of The Obvious

    Site Contributor
    10,000+ Posts
    • Jul 2007
    • 22698
    #1

    Opinions on laser theory, please

    I think that I've thought this all the way through, but I'd like to hear your thoughts on laser theory:

    This is the second time that I've seen this:
    (see attachments. I did not insert them ... I think it shrinks the image)

    It's on an e Studio 4505AC. The laser (LSU-UNIT-H376) has resolved the issue both times. Thin white voids through black halftones. CMY are entirely unaffected. If I calibrate 5 or 6 times consecutively the image improves markedly ... until the next time it calibrates itself.

    My main thought here is that this old laser might be a treasure trove of laser repair parts, assuming of course, that the defective item can be exchanged without a complex optical alignment.
    1) I'm going to throw out the idea of a laser board problem, only because the old laser is no longer a treasure trove of parts.
    2) I'm going to rule out a mirror motor (there are two: Y & M together, C & K together), since cyan should be equally affected. Unless maybe the angle of the laser diode shines light through a dirty portion of the mirror motor(?)
    3) Maybe a weak/bad laser diode? Perhaps the calibrations max out trying to compensate for a defective laser diode(?)
    4) Maybe a worn worm gear on the black mirror adjuster, de-focused latent image?

    I seem to recall that the two halves (Y & M, C & K) of the laser unit are exactly identical, so I could theoretically swap the left with the right. If the problem does not change, it would be a board or harness issue. If the problem moves to magenta, it's specific to the laser diode, mirror set, and mirror motor. At that point I could theoretically use the Y & M laser portion to repair another laser.

    I suppose that a vivisection of the black section of the old laser might reveal something.
    Do you see any flaws in my logic? Thoughts?
    =^..^=
    Attached Files
    If you'd like a serious answer to your request:
    1) demonstrate that you've read the manual
    2) demonstrate that you made some attempt to fix it.
    3) if you're going to ask about jams include the jam code.
    4) if you're going to ask about an error code include the error code.
    5) You are the person onsite. Only you can make observations.

    blackcat: Master Of The Obvious =^..^=
    Tags: diode, image, laser, mirror
    • Phil B.
      Field Supervisor

      10,000+ Posts
      • Jul 2016
      • 22808
      #2
      Re: Opinions on laser theory, please

      far be it from me to comment much on this brand, but in some xerox the 'mirror' is torqued depending on screw settings ( old school color)

      do you know how this one compensates? do you hear gears turning when doing adjustments?

      could the C motor be weak and not move it as much as the K?

      like I said not even competent on this brand much.

        Comment

        • Vincent128
          Trusted Tech

          Site Contributor
          250+ Posts
          • Sep 2015
          • 332
          #3
          Re: Opinions on laser theory, please

          Well...since Black mirrors are stationary and only CMY have alignment motors...It's got to be the laser diode or harness I would guess. ??

          I remember there being an issue with some Toshiba LSU's but that was a poly motor bearing issue. I never encountered that issue only seem to remember it popping up in conversation at the monthly regional meetings.

            Comment

            • allan
              RTFM!!

              5,000+ Posts
              • Apr 2010
              • 5445
              #4
              Re: Opinions on laser theory, please

              Feed direction on that?
              With or against the gradation pattern?
              Whatever

                Comment

                • Blizzoo
                  Senior Tech

                  Site Contributor
                  500+ Posts
                  • Aug 2013
                  • 588
                  #5
                  Re: Opinions on laser theory, please

                  I've seen that output as well I think 3 times on K only and yes, new LSU solved it. This was always in conjunction with CA20's.

                  Some says that could be the laserboard - not shooting 4 laser beam but instead only 2 of them or the CK polygon motor needs to be 'rised' a bit adding some really thin washers under the motor unit.

                  LSU is an expensive part and if you can fix one of them that's a good bonus.
                  Defects are simple, our mind is complicated

                    Comment

                    • blackcat4866
                      Master Of The Obvious

                      Site Contributor
                      10,000+ Posts
                      • Jul 2007
                      • 22698
                      #6
                      Re: Opinions on laser theory, please

                      Originally posted by Phil B.
                      far be it from me to comment much on this brand, but in some xerox the 'mirror' is torqued depending on screw settings ( old school color)

                      do you know how this one compensates? do you hear gears turning when doing adjustments?

                      could the C motor be weak and not move it as much as the K?
                      These mirror motors sit on alignment posts with only three screws holding them. I've had them out. There isn't any sort of alignment or positioning. I believe the laser image is focused using a worm gear drive at both ends of the 2nd laser mirror. I do not hear a noise specific to that, but these are very small mirrors (a cylinder 6mm dia, 12mm long). If it was the only motor running I doubt that I'd hear it specifically.

                      Originally posted by Vincent128
                      Well...since Black mirrors are stationary and only CMY have alignment motors...It's got to be the laser diode or harness I would guess. ??

                      I remember there being an issue with some Toshiba LSU's but that was a poly motor bearing issue. I never encountered that issue only seem to remember it popping up in conversation at the monthly regional meetings.
                      I would expect a mirror motor issue to express itself in both cyan and black, since they both use the same mirror motor. Since the left and right laser halves are identical, the black mirror must be adjustable, even if that adjustment is not used in calibration.

                      Originally posted by allan
                      Feed direction on that?
                      With or against the gradation pattern?
                      The voids are crossfeed ... main scan direction.

                      Originally posted by Blizzoo
                      I've seen that output as well I think 3 times on K only and yes, new LSU solved it. This was always in conjunction with CA20's.

                      Some says that could be the laserboard - not shooting 4 laser beam but instead only 2 of them or the CK polygon motor needs to be 'rised' a bit adding some really thin washers under the motor unit.

                      LSU is an expensive part and if you can fix one of them that's a good bonus.
                      That was my thought too.

                      Thanks everyone for your thoughts. =^..^=
                      If you'd like a serious answer to your request:
                      1) demonstrate that you've read the manual
                      2) demonstrate that you made some attempt to fix it.
                      3) if you're going to ask about jams include the jam code.
                      4) if you're going to ask about an error code include the error code.
                      5) You are the person onsite. Only you can make observations.

                      blackcat: Master Of The Obvious =^..^=

                        Comment

                        • djbass
                          Trusted Tech

                          100+ Posts
                          • May 2008
                          • 132
                          #7
                          Re: Opinions on laser theory, please

                          I assume by calibration you mean you've done a laser excitation adjustment?

                          I have seen something similar where the flat ribbon cable for a particular color is not properly seated.
                          No, I will not send you Manuals, Software or your own little repair Genie to fix all your problems for you.

                            Comment

                            • blackcat4866
                              Master Of The Obvious

                              Site Contributor
                              10,000+ Posts
                              • Jul 2007
                              • 22698
                              #8
                              Re: Opinions on laser theory, please

                              Sorry for the delay. The laser solved this one. Somebody else ended up finishing up the call. And it was a Hytec advance exchange, so we had to send it back.

                              My idea was to use the corpse to repair another laser unit ... no such luck. =^..^=
                              If you'd like a serious answer to your request:
                              1) demonstrate that you've read the manual
                              2) demonstrate that you made some attempt to fix it.
                              3) if you're going to ask about jams include the jam code.
                              4) if you're going to ask about an error code include the error code.
                              5) You are the person onsite. Only you can make observations.

                              blackcat: Master Of The Obvious =^..^=

                                Comment

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