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Electronic repairs on Elmo st-800

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  • Electronic repairs on Elmo st-800

    Because other projectors I have were showing signs of trouble with their electrolytic capacitors, I also took a look inside my st-800. Attached is why this needs addressing sooner than later for electronics this old. Not sure when this was made, but it's got to be close 40 years ago.

    I've only had a couple of items that showed this failure mode. Glad that I caught this before it got worse!
    Attached Files

  • #2
    Most of this is pretty easy stuff. But every so often there is a strange part. This has 9 leads, but looks otherwise like an electrolytic capacitor. Anyone know what this is? I don't have a service manual, just for the ST1200. that manual shows a couple of IC's that are 9 pin, but I can't tell that they are round like this.

    Click image for larger version

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    • #3
      Hello Jon,

      From what I can see on first picture above, there is not too much damage on copper track (to be confirm of course...).
      I suggest you to thoroughly wip off "green varnish" localy and untill copper appears (using Isopropyp Alcool, scotch brite and nitryl glothes).
      Then, coat copper track with a good electronic tin solder to protect and increase track conductivity.
      Second Picture : Unusual component shape . Try to report all marking information(s) and symbols marking (As +; -, AC symbol, values, etc...) which look to be hidden

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      • #4
        Originally posted by Jon Byler View Post
        Most of this is pretty easy stuff. But every so often there is a strange part. This has 9 leads, but looks otherwise like an electrolytic capacitor. Anyone know what this is? I don't have a service manual, just for the ST1200. that manual shows a couple of IC's that are 9 pin, but I can't tell that they are round like this.

        Click image for larger version

Name:	IMG_3490.JPG
Views:	102
Size:	282.3 KB
ID:	57267
        I would give good odds on that being an inductor or transformer of some sort. It reminds me of the bias oscillator coil in some tape recorders, does this projector have a recording feature by any chance?

        Post a picture of the top of it, I'm guessing it may have a ferrite core adjustment slot.

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        • #5
          This page has a picture of one from a 1980s Sony video recorder. https://www.palsite.com/950tech.html

          This is the picture from the Sony VCR. https://www.palsite.com/pics/bias_erase_transformer.jpg

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          • #6
            Originally posted by Jenny List View Post

            I would give good odds on that being an inductor or transformer of some sort. It reminds me of the bias oscillator coil in some tape recorders, does this projector have a recording feature by any chance?

            Post a picture of the top of it, I'm guessing it may have a ferrite core adjustment slot.
            No slot. this machine does have a record feature.

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            • #7
              Originally posted by Jenny List View Post
              This page has a picture of one from a 1980s Sony video recorder. https://www.palsite.com/950tech.html

              This is the picture from the Sony VCR. https://www.palsite.com/pics/bias_erase_transformer.jpg
              Thanks! that does look very similar.

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