ELMO ST-1200D Sound Issue #2 - Robert

[Robert Dreyer]

Something tells me it will be exactly that. Something so obvious that a rational person would not think of because we generally overthink a problem. Thank You Steve.

[Steve Lee]

This might be a long shot, but if the machine has not been used for some time, the grease on all of the moving parts could have hardened, stopping them from returning back to their positions.
It could be that the machine is stuck in record mode, and that's why it will not playback.
Just a thought.

[Robert Dreyer]

Steve, is there a way to look at the projector with the back off or with the front panel, pulled down, to see if specific gears are not turning?

[Rob Young]

I am not convinced, looking at Robert's pictures, that the sound head pressure assembly is in the correct position when engaging forward projection.

Although my own HD version is different, certainly the film should be pressed solidly against the sound head on projection (on my HD version, with sprung plastic pressure pads).

Also, the capstan pressure rubber roller that is part of the same assembly, should press solidly against the capstan roller when running normally.

I'm of the opinion that Steve's original diagnosis was correct and that the whole sound pressure assembly isn't engaging into the correct position.

[Robert Dreyer]

I have even thought about buying a 1200d for parts and replacing the sound head. As long nothing is spring loaded. I'd be willing to try anything.

[Robert Dreyer]

Rob, could I send more specific pics to confirm your theory?

[Rob Young]

Robert, if only I had my Elmo with me at the moment, I would take a video of the sound head assembly in action to post and then you could compare it with your machine.

Frustrating as I don't have it with me.

I still think there maybe an issue with the pressure assembly not moving into the correct position to push the film onto the sound head.

EDIT: Yes, Robert, please send as detailed info as you can and I'm sure we can all share and get to the bottom of this together here.

[Robert Dreyer]

Roger that. In the process of formulating.

[Robert Dreyer]

1- With power on only the power light comes on. Just making sure we are all on the same page

[Robert Dreyer]

The still position (Very top photo) shows the roller pushed very close to the sound head. I made an adjustment (5th photo down) showing the roller in the still position. The top screw (A) was unscrewed to allow this to happen. The gap (B) is present before turning to the projection mode. The only adjustment I was able to make. The projector over all appears to be very clean when purchased. If any photos need to be seen from the back side, please let me know. If we do get a resolution, This will be the first transatlantic repair work done online for me
Robert

[Steve Lee]

Hi Robert,
When you first receive the projector did it have the exciter lamp fitted?
I have studied the photos of your st1200 and it looks like someone has started to part this machine out. It is missing the lens assembly for the optical sound.
You said at the beginning that the bottom pinch roller was not turning when you received the machine.
The bottom pinch roller and capstan has to be working correctly, as this places tension on to the film as it passes through the sound head. Behind this pinch roller is where the solar cell sits for the optical sound.
If someone has had this assembly apart to remove the optical system for some reason, and has not resembled this assembly correctly this could be the problem with the sound.
Steve.

[Robert Dreyer]

As you see it is the way it arrived. No exciter lamp. The bottom roller (with the brass core and philip's head screw), if that is the pinch roller, turns very very slowly with no apparent power as it can be stopped and slowly turn counter clockwise and then slowly stop and then begin to slowly turn clockwise again. The film passes over this roller and does not turn like a free flowing roller but acts like a tension roller where the film drags over this roller that has some spin resistance. It is not to "pinch" in any way is it?

[Steve Lee]

When the sound is set to magnetic roller 1 should pivot down onto to the head when the machine is in play mode. Roller No 2 should also press down onto roller 3 trapping the film beween. when the sound is set to optical, roller 1 is pivoted up away from the magnetic head.
I have looked at other photos of this machine, and your machine is missing some parts.

[Robert Dreyer]

Is there a way to conduct tests to see if specific parts are present/ functioning? The only actions taken by me upon receiving the projector was to use an air can to blow out any debris that may have been in the inner workings. I've used an earphone to bypass the speaker and was able to hear the same hum increase and decrease as I adjust the volume control. This is the same when I plugged in an ext. speaker using a double earphone plug. From all appearances the speaker sound system seems to be fine. I think you're right that it seems like the problem is surrounding the sound head area. When using a magnet to move close to the sound head, I hear a warble that gets louder as you move close to it. If there was a way to manually move sound film, even a short piece just to test the system. Does the sound head transfer the sound to any other device before going to the speakers? Like you said if something was not put back correctly... For the lens assembly to be missing, is that a pretty extensive teardown to remove it? If so, then this may have been a parts projector. I am hearing different views of how the film should pass the sound head. At times I hear a loud pop when the last frame of the reel passes the sound head. The film was adjusted to pass within 1/16 or 3/32 of an inch. Maybe it needs to be pinched down to actually pass as if it was going over a roller? If so, we may be moving closer to a remedy.

[Rob Young]

Hi Robert. Unfortunately the design of your D model is a little different to my own HD version. That said, the film must be pushed directly against the sound head for it to work. Like a tape recorder, the magnetic stripes must be making direct contact and held there by a pressure pad or roller. In the case of your pictures, it would seem roller 1 should be pushing the film directly to make contact with the metal sound head.

As Steve has commented, Roller 3, with the brass center is the capstan. This is linked to a large rotating weight, a metal flywheel, in the back of the machine. It is free moving on the ST models, so you will be able to turn it manually. The resistance you feel is the weight. When the film is running, a roller (no.2 it looks like on your machine) should again push the film firmly against the capstan. By pinching it onto the capstan, the capstan quickly builds up a rolling speed to match the film speed. The idea being that it then pulls the film smoothly across the sound head at 18 or 24 frames per second without wow or flutter. So again, the film should be being held firmly against the capstan by the roller above when running.

Unfortunately, as others have observed, the optical lens assembly is missing, suggesting that the machine has been tampered with previously, so its hard to know what other damage may have been done.

The frame counter not working is indeed just a belt missing. Not uncommon on these machines for it to snap. It doesn't affect anything else.