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Screen rot

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  • Mike Loewen
    Before: http://sturgeon.css.psu.edu/~mloewen/Oldtech/Terminals/HP2647A-1L.jpg After: http://sturgeon.css.psu.edu/~mloewen/Oldtech/Terminals/HP2647A-37L.jpg
    Message 1 of 7 , May 3, 2012
    • Matt Patoray
      Great work Mike! Take some good pictures for those of us that will not be able to make it! Matt Sent from my iPhone
      Message 2 of 7 , May 3, 2012
        Great work Mike!

        Take some good pictures for those of us that will not be able to make it!

        Matt

        Sent from my iPhone

        On May 3, 2012, at 5:11 PM, Mike Loewen <mloewen@...> wrote:

      • joshbensadon
        Hi Mike, That s quite interesting, but I m a newbie here and I m not sure what I m looking at. On the before picture, is that some kind of deterioration of
        Message 3 of 7 , May 3, 2012
          Hi Mike,

          That's quite interesting, but I'm a newbie here and I'm not sure what I'm looking at. On the before picture, is that some kind of deterioration of the screen glass or the mask? Or is it related to the cathode emmisions? I remember using a crt screen rejuvinator long ago. It was a device that supposidly baked oxide off the cathode. I never had much success with it though. We were using that device in our shop to put life back into some CCTV monitors used for security. But it only worked for some of the monitors and not for very long. We went back to replacing the CRT's as the standard practice.

          Cheers,
          Josh






          --- In midatlanticretro@yahoogroups.com, Mike Loewen <mloewen@...> wrote:
          >
          >
          > Before:
          >
          > http://sturgeon.css.psu.edu/~mloewen/Oldtech/Terminals/HP2647A-1L.jpg
          >
          > After:
          >
          > http://sturgeon.css.psu.edu/~mloewen/Oldtech/Terminals/HP2647A-37L.jpg
          >
          >
          > Mike Loewen mloewen@...
          > Old Technology http://sturgeon.css.psu.edu/~mloewen/Oldtech/
          >
        • Kyle Owen
          I believe in this case, it s the mask. Over time, the glue holding the mask on breaks down and bubbles up, making the CRT unusable. The process for restoring
          Message 4 of 7 , May 3, 2012
            I believe in this case, it's the mask. Over time, the glue holding the mask on breaks down and bubbles up, making the CRT unusable. The process for restoring the display is typically taking the whole thing apart, getting the glue off (scraping it, or maybe some sort of solvent), and possibly putting some new plastic over it, generally without the glue. I'm pretty sure the glue was originally there to keep the internal reflections (between the mask and CRT) as low as possible. But I'm sure Mike can explain his process in more detail.

            Kyle

            On Thu, May 3, 2012 at 8:07 PM, joshbensadon <no_reply@yahoogroups.com> wrote:
             

            Hi Mike,

            That's quite interesting, but I'm a newbie here and I'm not sure what I'm looking at. On the before picture, is that some kind of deterioration of the screen glass or the mask? Or is it related to the cathode emmisions? I remember using a crt screen rejuvinator long ago. It was a device that supposidly baked oxide off the cathode. I never had much success with it though. We were using that device in our shop to put life back into some CCTV monitors used for security. But it only worked for some of the monitors and not for very long. We went back to replacing the CRT's as the standard practice.

            Cheers,
            Josh

            > Mike Loewen mloewen@...
            > Old Technology http://sturgeon.css.psu.edu/~mloewen/Oldtech/
            >


          • s100doctor
            ... This also happens with ADM-3A terminals. The fix I m familiar with, is a heat gun and a paint scraper, and a cushion to catch the outside glass as you
            Message 5 of 7 , May 3, 2012
              Kyle Owen <kylevowen@...> wrote:
              >
              > I believe in this case, it's the mask. Over time, the glue holding the mask
              > on breaks down and bubbles up, making the CRT unusable. The process for
              > restoring the display is typically taking the whole thing apart, getting
              > the glue off (scraping it, or maybe some sort of solvent), and possibly
              > putting some new plastic over it, generally without the glue. I'm pretty
              > sure the glue was originally there to keep the internal reflections
              > (between the mask and CRT) as low as possible. But I'm sure Mike can
              > explain his process in more detail.
              >
              > Kyle

              This also happens with ADM-3A terminals. The "fix" I'm familiar with, is a heat gun and a paint scraper, and a cushion to catch the outside glass as you slide it off. Heat melts the "glue", apparently. When I have time I can provide a link. I ought to add such info to my ADM-3A Web page....

              I didn't see discussion of this repair as linked to Mike's description of the repaired terminal. Mike, any chance you have this on your site, or can put it there?

              Herb
            • Mike Loewen
              ... Kyle: What you re calling the mask is what many call the faceplate . I tried several thingss, including: 1. Using some wooden clay knives to dig out
              Message 6 of 7 , May 3, 2012
                On Fri, 4 May 2012, s100doctor wrote:

                > Kyle Owen <kylevowen@...> wrote:
                >>
                >> I believe in this case, it's the mask. Over time, the glue holding the mask
                >> on breaks down and bubbles up, making the CRT unusable. The process for
                >> restoring the display is typically taking the whole thing apart, getting
                >> the glue off (scraping it, or maybe some sort of solvent), and possibly
                >> putting some new plastic over it, generally without the glue. I'm pretty
                >> sure the glue was originally there to keep the internal reflections
                >> (between the mask and CRT) as low as possible. But I'm sure Mike can
                >> explain his process in more detail.
                >>
                >> Kyle

                Kyle:

                What you're calling the "mask" is what many call the "faceplate". I
                tried several thingss, including:

                1. Using some wooden clay "knives" to dig out the adhesive for about an
                inch around the edges. You find them in craft stores.

                2. Nichrome wire connected to a 12V power supply. Not enough current,
                although the wire did get hot enough to melt a bit of adhesive. Then the
                wire snapped (too thin). Most people say to use a battery.

                3. Acetone applied to the adhesive through the gap from step one. The
                acetone helped to soften the adhesive, but didn't do a lot of good.

                4. Heat gun, which most people use (or a thicker hot wire). I was very
                nervous about using the heat gun, and had to hold it on longer than I
                thought prudent. I used a couple of the wooden knives to put some
                pressure between the CRT and the faceplate, which finally loosened.

                5. Peeled most of the remaining sheet of adhesive off.

                6. Cleaned off the adhesive residue with a plastic scraper and acetone.
                Then Windex and a soft cloth. Temporarily reattached the faceplate with
                double-sided foam tape strips. I will eventually reattach it with a
                couple of beads of clear silicone around the edges.

                > This also happens with ADM-3A terminals. The "fix" I'm familiar with, is
                > a heat gun and a paint scraper, and a cushion to catch the outside glass
                > as you slide it off. Heat melts the "glue", apparently. When I have time
                > I can provide a link. I ought to add such info to my ADM-3A Web page....

                Herb:

                That's pretty much the procedure I used. There is a set of videos on
                YouTube that document the procedure on an old TV set.

                > I didn't see discussion of this repair as linked to Mike's description
                > of the repaired terminal. Mike, any chance you have this on your site,
                > or can put it there?

                I regret that I didn't have time to take any pictures of the process,
                but will document what I can, post-VCF. I was in a hurry, as this
                terminal is part of my exhibit and I decided to try this at the last
                minute. The display was almost unreadable.

                I don't really recommend that people try this, but I was desparate.
                I've read about CRTs imploding and faceplates cracking. You also run the
                risk of cracking the tube neck, and letting out the vacuum. It's akin to
                letting out the magic chip smoke. :-)


                Mike Loewen mloewen@...
                Old Technology http://sturgeon.css.psu.edu/~mloewen/Oldtech/
              • joshbensadon
                ... The mask is internal to the CRT, I wouldn t think it would be possible to repair such a thing without some very special techniques. ... A tube once
                Message 7 of 7 , May 4, 2012
                  > What you're calling the "mask" is what many call the "faceplate". I
                  > tried several thingss, including:

                  The mask is internal to the CRT, I wouldn't think it would be possible to repair such a thing without some very special techniques.

                  > I've read about CRTs imploding and faceplates cracking. You also run the
                  > risk of cracking the tube neck, and letting out the vacuum. It's

                  A tube once imploded on my co-worker, fortunately, it was only a 12" CRT and it didn't make any damage. We then were always careful to wear our safety glasses around these things.

                  I once finished fixing a 26" colour tv, then turning the chassis back over, I nicked the vacuum stem and heard a big swoosh of air... DAMN!

                  Anyway, my point I want to stress here is...

                  Wear Saftey Glasses!
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