8mm Forum: Elmo st 800 sound problem

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Posted by Bradford A Moore (Member # 426) on October 18, 2009, 11:01 AM:

Hey Guys,

I had already tried all that you mentioned, and still no sound. I have never had stay off this long. The last time it was on, it sounded fine. Over the last couple of days, it would go off between reels, but if I waited a little bit it come back on. John Black suggested the electronic cleaner, but still no sound. I was amazed how dirty the heads were, I'm usually very good about all that. I hope this isn't something more serious, because I have just started my winter film series on Thursday nights.

Brad

Posted by Dan Lail (Member # 18) on October 18, 2009, 11:57 AM:

Brad, are you using an external speaker or the speaker in the projector? Check the speaker wire connections. When you turn the sound on do you head white noise in the speaker(normal) even though no sound is heard when running a film. Is this the optical/magnetic ST-800? If you are not using an external speaker, try using one if possible. see what happens.

I'm sure "Mr. Elmo" will zero in on this problem. [Big Grin]

Posted by Steve Klare (Member # 12) on October 18, 2009, 11:59 AM:

There is a possibility here:

I lost sound completely on my own ST-800 about a year ago, and it just wouldn't come back whatever I tried. I don't have schematics to troubleshoot down to components, so fixing this had to come down to replacing entire assemblies. I happened to find a projector that had basically brand new guts, but the frame was damaged so that it couldn't run. One Saturday I sat down and transferred all these wonderful, mint condition parts onto my good frame, and basically built myself a brand-new Elmo ST-800.

The interesting part of the story (for you) is when I removed my old sound head assembly I found that a wire from the head had become detatched. There is a tiny circuit board right under the framing knob that these wires are attached to by a surface solder joint, which had let loose from the board and disconnected the signal out to the sound board. Had I seen this first, I probably would have been able to fix the projector without transplant surgery (-not that I mind having a brand new set of heads, boards and guides anyway...)

See if you can find this little board and gently prod the wires to see if one is dangling loose: this could be it.

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