8mm Forum: UPDATE/ Wow & flutter, 1200HD Lower Rollers

This is topic UPDATE/ Wow & flutter, 1200HD Lower Rollers in forum 8mm Forum at 8mm Forum.

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Posted by Tom Photiou (Member # 130) on 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.

Posted by Rob Young. (Member # 131) on December 20, 2018, 09:36 AM:

Hi Tom, let us know how you get on with this as wow is one the problems with the ST.

Like you say, most prints are fine, but some polyester prints just seem determined to wow. The sight of those two jockey rollers moving up and down, together with the wow used to drive me crazy on some prints.

I think the rounding of the rubber may just be down to the rubber aging and shrinking? I think harmful chemicals would more likely have cause cracking.

Posted by Tom Photiou (Member # 130) on December 20, 2018, 09:41 AM:

Thanks Rob, i will let you know Monday as i will hopefully, be putting a film through over the weekend.
If it works i will only have three of these left so i will need to try and see if i can get some remade. The two lower ones i had replaced a couple of years ago were like the one shown here. If you rolled it gently on a flat table they wobbled like a weeble.
Again, it is only those darn polyester prints that occasionally cause the problem and only then, a few titles.

Posted by Rob Young. (Member # 131) on December 20, 2018, 11:06 AM:

I know, Tom. I would buy brand new polyester features from Derann in the 90's and most would run like a dream, but then some would act up and wow.

Beauty and the Beast springs to mind. It kinda ruined the experience. I tried Filmguard, everything...

They would run perfectly on the Beaulieu, but then the sound quality wasn't as good as the booming ST. Very odd.

Posted by Tom Photiou (Member # 130) on December 20, 2018, 03:01 PM:

It is weird how some films do differ, we also have Beauty and the beast and also the lion King, yet these two appear to play fine. Looking at these images, this is what it all looked like once i got the pad roller lever out with the original roller still in place. What a mess. I always thought i did a good job of cleaning. Just goes to show what gets in the places you cant get in to.

Posted by Tom Photiou (Member # 130) on January 04, 2019, 07:41 AM:

I have now found some time to try out this minor repair. Unfortunatly, at this time it hasn't cured the wow i get on a few poly prints. Very annoying as looking at the state of the old roller i thought i had this solved. However, after 40 years of owning this machine i am still very pleased with it. This is the first time i have had this problem to this extent, however, equally annoying is the fact it only happens on a handful of prints and they are all polyester prints, all other films are 100% perfect.
It's back to the drawing board now to see what i can do next, the films are not over or under cleaned and the area of concern is still within that roller pad lever because if i press down on it when it's playing the two lower rollers lift up and all wow ceases.

Posted by Mathew James (Member # 4581) on 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!

Posted by Tom Photiou (Member # 130) on January 04, 2019, 09:12 AM:

To be fair, up until now for almost 40 years this machine has been like clockwork, the only time i do get this happening is with a handful of poly prints. All other films are perfect. Bill parsons did say to me in the past that all the factory setting of projectors we use today didn't take into account the extra thin polyester stock as it wasn't around in the day. I am fully aware that these machines can have this problem and other makes out there are fine so i will now seek to sort out my spare 1200HD and see how that one performs.
I'm certainly not looking to replace the machine unless a bargain comes along. Especially as it is only a handful of movies. [Wink]

Posted by Paul Adsett (Member # 25) on 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.

Posted by Rob Young. (Member # 131) on January 15, 2019, 09:33 AM:

Same here, but no wow on the Beaulieu.

Shame that didn't completely fix it Tom, but our projectors keep us busy at least.
[Smile]

Posted by Phil Murat (Member # 5148) on January 15, 2019, 09:57 AM:

Hello Rob,

This issue is very rare on Beaulieu 708.

As Beaulieu's system is different from Elmo and other machines, I suggest you to check drive belt and/or capstan motor for proper operation.

Have also a look on head press pads and film path in heads area

Perform a film pulling check to insure roller pinching efficiency

Phil

Posted by Rob Young. (Member # 131) on January 15, 2019, 10:44 AM:

Sorry Phil, maybe I wasn’t too clear - I never get wow on my Beaulieu, but I do suffer the same occasionall Elmo wow as Tom.

Posted by Phil Murat (Member # 5148) on January 15, 2019, 01:29 PM:

Yes Rob , I just realize I read too fast (now WOW on Beaulieu instead of no WOW on Beaulieu)..... [Wink]

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