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Author
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Topic: UPDATE/ Wow & flutter, 1200HD Lower Rollers
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Tom Photiou
Film God
Posts: 4837
From: Plymouth U.K
Registered: Dec 2003
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posted December 20, 2018 08:42 AM
While i will always praise up my Elmo ST1200HD's as being one most proven projectors made for super 8, the one thing that they could have improved on is that tiny sized sound drum. The one area that has caused me a few wow problems on the sound. However, the only films i have an occasional problem with this is polyester films. Notably, The Snowman, being all musical it stands out more. As a footnote, this year when we viewed it there didn't seem to be a problem as hopefully the filmguard on the film had now settled. A few other films, but not Grease, which is odd.
When my HD was given its last major overhaul before Mr Parsons retired, one of the things i had done was to replace the two lower rollers with brand new ones i had from Hanimax years ago. The mistake i made at that time was not sending a third to replace the one in the pad lever, the part which presses down onto the sound drum in forward. Although the spring was adjusted all the way to the right for maximum pressure i was still getting some wow on those polyester prints. Following advice,I pressed down on the pad lever when i was getting the wow and once i applied pressure the sound was perfect. Take the finger off and you can clearly see those two lower rollers gently moving up and down, hence the wow.
I purchased the last four of these rollers from Leon. Following some advice from Bill,(and practising on my spare HD), i removed and replaced the roller.
Onto my main machine, once i took out the pad roller lever i could get into places at the bottom of the head that ive never seen before. It's unreal how much muck can gather in these places so obviously i gave it all a good clean out as well cleaning the heads with cassette head cleaner.
Once i got that roller out i was quite taken back by the state of it. The surface is meant to completely flat so when it presses down onto the film against the sound drum it's meant to hold the film perfectly flat to allow the film to move through smoothly. Bill did say that sometimes the rubber goes very hard, this one is both rock hard but also rounded so only 50% of the rubber surface was pressing against the film.
While i have to test it now i am quite confident that this should work or at least make a 90% improvement. If it doesn't i will be back to square one but i'm sure this will do the trick.
Because i wanted to try and "go by the book" and get the pressure dead right, the cost of the spring scales were ridiculous for the use i would get out of them, but as i was reminded, all these machines were designed and built with the settings made for acetate film. Polyester was not out then. Poly film is so thin that the pressure may need to be stronger not to mention of course the use of stuff like filmguard which if over applied will cause all sorts of problems. Although i think i have now mastered filmguard, i for one was definatly over applying in the early days. All that crap cant do any of the projector parts any good, 222 was great but this stuff with it's heavy chemical make up must also have had a bearing on rubber parts over the years. How else does something make a flat rubber surface go so rounded?
Here are images of the four new ones and the old wonky one, this is all it takes to cause problems, and of course scratching.
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Mathew James
Jedi Master Film Handler
Posts: 740
From: Hamilton, Ontario, Canada
Registered: Dec 2014
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posted January 04, 2019 08:33 AM
I wish I could help Tom, but I think I must have really lucked out in my ST1200HD...as I never have yet heard this wonkiness when playing, but know others have...
The ONLY thing i have ever noticed on mine is that when I first started up, it was not always as fast as it is a minute later....I noticed there was some old grease buildup starting on the shutter blade wheel thingy. I put a q tip in and clean it so there is nothing to slow this wheel to slow down ever and it seems to have helped with mine.
I think I lucked out because even though this was some 40 years old when i bought it, it didn't seemed ever used, so all i had to so was belts and such...so far, luckily!
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Cheers,
Matt 📽
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Paul Adsett
Film God
Posts: 5003
From: USA
Registered: Jun 2003
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posted January 04, 2019 02:24 PM
Tom, the root cause of all the WOW problem on the Elmo's is the small diameter of both the sound capstan and the pinch roller. Look at the Eumigs, none of which have ever exhibited even a trace of WOW and you will see the much larger diameter of the capstan and the pinch roller as well as the much higher clamping force between the two. Because of the poor Elmo capstan design, both the GS1200 and the ST1200 can be very fussy with different films, depending on a number of factors:
Take-up tension and tension variation caused by the take up motor.
Coefficient of friction of the film, dry or how much lubrication.
Film base thickness and bending stiffness.
My GS will run 90% of my films with no noticeable wow issues, but the other 10% will wow every time, but will never wow on any of my Eumig's.
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The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj
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