8mm Forum: Elmo GS-1200 - Sound Sync Issue

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Posted by Peter Harrison (Member # 5290) on October 05, 2016, 08:12 AM:

Hello all,

Recently in another post about my troublesome Elmo ST-600 I mentioned that I was considering getting a larger projector rather than investing too much time and money in fixing that particular model. Well, I tool the plunge and recently bought a GS-1200.

Purchased as a bit of a gamble from a listing on Yahoo auctions that wrote it up as untested, I was surprised when I received the thing and it looked to be in great condition with barely a scratch, scrape or stain present. It looks like it has not been removed from its case while having been in storage (for all the good and bad that entails).

Well, anyway, tonight I unpacked her, dusted her off and held my breath before firing her up. To my surprise all seemed great. I checked her over before running her for a little while and when all seemed okay I put my usual test film in to give it a whirl. Once the take up reel picked up the header the lamp fired up nicely and I got a beautiful, bright, sharp picture out of its f1.1 lens. I was all smiles.

But... after this brief honeymoon period I noticed something of an issue. For a reason I am yet to determine, the audio is playing out of sync with the image. There is about a second delay on the picture on screen versus the sound. I ran my test film through my Eumig and even the ST-600 and it is nothing to do with the print.

While I've looked in the manual to see if there is mention of a delay being something that it is possible to manipulate, other than the pulse sync controls (which I believe function with a tape deck) and the dial to speed up/slow down the sound in unison with the image, nothing leaps out at me as untoward. Therefore, I'm wondering if anyone knows if there is a simple answer to this or whether there might be a fault causing it that requires some tinkering?

The service manual makes no mention of sync issues as a problem (as far as I could see) so I'm hoping this is just down to me being a bit thick. If this problem has already been encountered please feel free to just forward me to that thread.

Cheers,

Peter

Posted by Brian Fretwell (Member # 4302) on October 05, 2016, 10:53 AM:

I would have thought sync problems would be due to the wrong length of film between the gate and the sound heads.
One second advance of sound over picture would mean 24 frames less in the loop below the gate which sounds a lot to me, about three inches. I don't know the film path of this projector but I'm sure many here do and can offer more exact theories.

Posted by Bill Brandenstein (Member # 892) on October 05, 2016, 11:57 AM:

If the film doesn't grab correctly while threading - for example, because of mis-shapen Fiesta leader - you can end up with a delayed engaging of the lower sprocket, resulting in an unwanted loop of film below the gate and before the sound head. This can be very destructive, of course, and is likely to scratch. However, if you have the cover open, it should be obvious that something is wrong. So just make sure the film path is correct for starters.

Posted by Paul Browning (Member # 2715) on October 05, 2016, 12:44 PM:

Hi Peter, make sure you trimmed the end with the Elmo trimmer, first off, this can make a difference sometimes. This has a latch switch just above the first cog just after the guide, (little red arrow ). When it laces up and the film is present at the rear, does the latch switch click back to the home position ?. This is micro switch operated and can stick from time to time, or when unused for some time. The last roller before it feeds onto the rear reel actuates this operation, so you can see this working if you operate as though you have film in, latch front switch and then gently press the roller this should return to the off position. I have had this too, and I was with Derek Simmonds at derann, he is simply got a biro and flicked the top loop out a bit, fixed in an instant.

Posted by Maurice Leakey (Member # 916) on October 05, 2016, 02:55 PM:

The loop below the gate seems to be too large, probably caused by incorrect threading.
As Paul says, make sure you use the film trimmer, also ensure the film has a gentle backwards curve to it.
After film cutting, depress auto-thread lever until it locks.
Press FWD button.
Insert film leader into the auto-thread slot as indicated by the red arrow.
When film reaches the take-up spool the auto-thread lever will release automatically.
Referring to Paul again, it is possible that the auto-thread is not realising automatically. If so, release by hand.
I now suggest you press STOP. Pull down the side cover and look at the loop below the gate, it should be relatively small, depending on the production year the loop may face forwards or backwards.
As perhaps the Elmo has had very little use for some time it might be a good idea to look at its general lubrication.

Posted by Brian Fretwell (Member # 4302) on October 05, 2016, 04:51 PM:

Surely if the loop was too big there would be a delay of sound behind picture not picture after sound, which is how I read what Peter put.

Posted by Jason Smith (Member # 5055) on October 05, 2016, 06:41 PM:

On a seperate note, (if you haven`t already)do check the input guide, upper sprocket guide, and the film tensioner for wear. I would also double check to make sure all of the rollers are running smoothly.

Posted by Maurice Leakey (Member # 916) on October 06, 2016, 01:52 AM:

I must admit I wasn't too sure of Peter's description of the sound discrepancy.
Perhaps he can clear up this point.
Is sound ahead of picture, or picture ahead of sound?

Posted by Peter Harrison (Member # 5290) on October 06, 2016, 07:46 AM:

Hello everyone,

Thank you all very much for your input and sorry for the lack of precisian in my explanation. I must also apologise for the exaggeration in my having said there was a one-second delay. It was less than that, though I wont hazard any further guesses. To clarify, the delay was on the sound (car silently explodes, cut to kittens playing, *BOOM*...).

I put my test film through again today with the cover off while following the film track carefully with a torch. In looking for excessive loops after the gate I found one. Here's a picture I've edited to illustrate where:

Where the arrow points there is a wedge-shaped (pie slice), black "guide" that pivots left and right at the wedge's point. When the auto threading is working it sits to the left and after the take-up reel has engaged and the lamp comes on it moves over to the right. As I see it this seems like a scratch risk as the film hitting it appears to be what is moving it there (but that could just be my machine or my mistake). I found that a small loop was forming here for reasons I'm as yet unsure of.

Once I'd removed the film I gave this wedge a push with a screwdriver to see whether it is operated mechanically or not. While it swung left and right with no mechanical resistance (nothing seems to engage or disengage it as such) it did do so a little stiffly.

Running the film through again with special attention to this point, the loop/bulge did not form and the sound played in sync with the picture, which is good.

What I was hoping somebody might be able to explain to me is the proper functioning of this black pie-shaped part. Should it be able to swing back and forth freely or is a spring or some kind of engaging mechanism playing up?

The curved edge of the wedge is recessed like the gutter of the loop former but never seems to be in a position to steer the film. Also, when the movie plays the flat side merely seems to provide something for the film to scratch on rather than perform any particular task. Seems a bit odd to me... (but I'm not in a position to judge).

What I plan to do is give the film track a thorough cleaning throughout and lubricate all rollers. I'm also going to buy a Van-Eck film guide/loop former as that is also showing slight signs of wear.

In respect to lubricating rollers, would anyone happen to know a good supplier and equivalent of the Daphne 44 mineral oil mentioned in the service manual?

Thank you all for your help thus far and for any further advice/insight. I am very appreciative to have such a wealth of knowledge shared with me so liberally.

Cheers,

Peter

Posted by Maurice Leakey (Member # 916) on October 06, 2016, 10:38 AM:

Peter
It look as it the loop former bracket is missing, this is a long black arm which pivots and is controlled by the lever on the hinging down side cover. This is for reforming a lost bottom loop.
I am not too sure what you are describing.
As regards oil for rollers, etc., use a light oil such as that sold for sewing machines.

Posted by Paul Browning (Member # 2715) on October 06, 2016, 01:05 PM:

It forms a loop just before the roller your arrow is just pointing at peter and is spring loaded. Just could be lack of use in your case here. It maybe the rubber is not turning every time, or needs a clean with iso to get smooth but dry. You could just spray a little wd on a cotton swab and dab the bearing top, i'm not sure if they are phosphor bronze or not, which are self lubricating. You actually have a later mk 3 model, looking at the green guide bush, and so the lower loop former is facing backward, check this for wear marks as this can show flats across its width, a mod rubber roller is its replacement now.

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