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ELMO ST-800 - No sound!

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  • ELMO ST-800 - No sound!

    Now I know what you're all thinking... work those switches, break down oxide! Unfortunately, after trying that and more, I'm out of options.

    Allow me to give some background:

    I purchased this projector about 5 years ago and the seller said it was "serviced." Not really sure what was done, but I was just happy it worked. After a few months, the sound would cut out occasionally. Finally it totally stopped. After some light digging, I found posts on the old forum explaining the situation and what to do. Sure enough, I pressed the big red record key a few times, and the sound returned!

    ...only to stop again a few weeks later. Could it be more oxide buildup? Who knows! I've never gotten the sound to work again

    So far I've:

    -Jiggled the record key a few hundred times
    -Stuck a 3.5mm jack into all the aux/mic sockets rapidly to try and break up anything in there
    -Lightly sprayed DeoxIT D5 into the sockets and tried again
    -Did some disassembly to get as close as I could to the spring switch that the record key is connected to. I don't exactly know electrically what is happening inside that switch, but I did my best to spray DeoxIT D5 directly into it and work the record key up and down another few dozen times.

    No dice!

    Hopefully someone has another recommendation or tip to try. A service manual would be great as well-- I found PDFs for the 600 and 1200, but the mechanisms aren't exactly the same.

    Thank you!


    Edit: Also worth noting that there is an audible pop when the volume is turned on and off, as well as light speaker hum when it's cranked all the way up, so there's definitely power running into the speaker.
    Last edited by Tyler Ortel; September 02, 2021, 01:07 PM.

  • #2
    Could be dry joint on the board, or blown amp module, not sure if this has a fuse on the amp section, but if it does, when the machines off remove the fuse and check that its ok. I have known these look good but are shot, check with a meter on diode setting, it should beep if its ok, remember some of the fuses are soldered on the ends and they break there just beyond the metal ends, so the fuse wire is still in place, when standing for some time all kinds of problems take place with no use, just switching it on could take out a fuse, check them first, and there is a way of checking the output module on the these, i think they are the sanyo hybrid upright, but try those couple of things first. The amount of dead projectors i have brought back to life because the fuse has crudded up in position or no one has checked it.....


    • #3
      Hi Tyler,

      The instinctive answer with these is always the Switch Trick, and it often helps...but not always.

      I've been making mute ST-800s loud again since 2003, so I may have something obscure you can try. There is a tiny printed circuit board mounted to the chassis near the framing knob. I believe its whole reason for existence is unite the wire from the sound head over to more wire out to the sound board.

      I had one of these a bunch of years ago where one sound head wire broke off. For some reason known only to Elmo, the wires are only surface soldered onto this board and the bond just let loose.

      -no guarantees, but it could happen twice.

      (best of luck!)

      PS: The pop and hum is telling me that your amp is powered and probably active too. If you have a microphone, you could go into PA mode and test the amp, maybe entertain your friends and family too!

      An ST-800 service manual has been my quest for about 18 years now. I'm sure they exist, in moldy file cabinets in the basements of abandoned camera shops. Other than that...?


      • #4
        I have a elmo 16mm projector that did the exact same thing, but checking the amp module showed it was shot. If you have a meter try this, plug machine in to mains, switch on, leave volume control set to minimum, set meter to volts, place one probe on chassis ground of the machine, a metal screw on the outside connected to the chassis will do, place the other probe on the speaker socket output, if the amp is good it will show micro volts, if it shows more than 20v the amp is shot. This is a write up on an audio page on the net, from someone who knows how to checks these devices.............