Film-Tech Forum ARCHIVE: Simplex 35 Speed Issue

my profile | my password | search | faq & rules | forum home

»	Film-Tech Forum ARCHIVE » Operations » Film Handlers' Forum » Simplex 35 Speed Issue (Page 2)

This topic comprises 2 pages: 1 2

Author

Topic: Simplex 35 Speed Issue

Darryl Spicer
Film God

Posts: 3250
From: Lexington, KY, USA
Registered: Dec 2000

posted 05-28-2008 12:54 PM

quote: Sean McKinnon
If it was the motor wouldn't both the projector head and the soundhead slow down and speed up at the same time? He says that the film is "bulging" out between the lower holdback sprocket and the sound drum which would lead me to beleive that the projector head is moving at a steady speed while the constant velocity sprocket in the soundhead is slowing down, or there is intermittent drag on the sound drum itself. Is that off base?

In that case I would lean towards the sound drum having a drag in it. If the film is bulging out between the projector head and the sound drum. Since the motor drives the sound reproducer and the sound reproducer drives the projector head all variations in speed caused by the motor would affect both equally. Even if there are bearing issues in the sound reproducer drive shaft it would affect the speed of the projector head the same since the drive for that head is coming from that shaft. Change the sound drum bearings if the drum does not spin freely without resistance. If the drum is turning like it is supposed to then check the bearings in the lateral guide roller assembly.

I would say humidity affects the bearings a lot. Every time I have had to change out bearings in both the drive shaft and the sound drum I have been met with rust accumulation.

| IP: Logged

Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 05-28-2008 01:18 PM

Sean, incorrect.

If the motor slows down, at all...the film will tighten as the drum speed, via the flywheel will try to keep going the same speed but will eventually loose the battle (rather quickly). Then when the motor speeds up, again the drum will try to hold the same slow speed but the first thing that will happen is that the damper roller will swing over and create bowing of the film from the projector to the drum. When the drum reaches the new projector speed the damper roller will swing back and pull the bow back.

Though more violent, you can try this with the motor switch to see it in action....hence a possibility to the problem is a bad contact on either the motor switch or the automation relay.

Steve

| IP: Logged

Chad M Calpito
Master Film Handler

Posts: 435
From: San Diego, CA
Registered: Apr 2006

posted 05-31-2008 01:43 AM

Sorry it took me a while to make another post. Anyway, here is the update. The motor I am using for #9 is the Ballantyne motor. The problem was fixed. From the service note: the Bearings needed replacing. The Sound Drum was not able to keep pace with the speed of the projector hence the occassional slowing down and then, speeding back up to normal. Anyway, I hope I worded this right.

| IP: Logged

Sean McKinnon
Phenomenal Film Handler

Posts: 1712
From: Peabody Massachusetts
Registered: Sep 2000

posted 05-31-2008 09:58 AM

So, I guess I was correct. After visiting my friends theatre with the same Simplex 35's and 5 Starts I observed that if the motor was infact slowing and speeding up it would cause the film to alternately buldge out both above and below the sound drum because the lower holdback sprocket in the picture head and the constant velocity sprocket in the soundhead would still both operate at the same speed as each other. As the machine slows the still spinning sound drum will keep pulling the film out of the picture head and cause a buldge between it and the soundhead sprocket, as it speeds up the reverse will occur. What chad described was different from this. He described the film only buldging between the picture head lower holdback sprocket and the sound drum which says to me that the bearings on the sound drum are bad and not the motor.

| IP: Logged

Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 05-31-2008 04:33 PM

Sean,

The buldge, below the sound drum, would be taken up by the damper in the 5-star soundhead pretty briskly as such, most would not see the buldge below. Conversely, the buldge above, would require the flywheel to come up to speed, before the buldge would be pulled away...by the damper arm.

I tend to approach such repairs with a very open mind rather than go in with a set idea that may lead my down the wrong path.

For instance...I was paged last night...lamp would not strike...reset the breakers...still no lamp. The theatre owner was convinced it was a diode failure...after all, he has experience those. A diode failure can easily and probably most often is the cause of such problems. However, upon arrival...it took mere moments to discover that not one but TWO of the three legs of the 3-phase power were gone due to a failed 3-phase breaker.

One thing I see too many techs do is jump to conclusions too fast. Keep an open mind and let what you discover lead you to the problem.

When a problem like the one described here comes up, I tend to think of all of the potential possibilities rather than just think that only one thing could cause the symptoms. Furthermore, the description given over the phone (or in this case in text) is someone else's observations baised on their own experience or lack there of (includng lack of terminology).

Today's page was an unusual one. The call was "we have some bad ghosting...it comes and it goes." The projector was a Simplex Millenium. I first ran the projector and noted no ghosting...in fact, shutter timing seemed quite good. I then started seeing if there was any slop in the gear train...I found that the shutter compensator was pretty gummed up (PEOPLE, THE OIL NEEDS TO BE CHANGED BEFORE IT BECOMES A SOLID)...As such, if you framed the projector...it would take awhile before the shutter compensator would...well....compensate...so I'm thinking...a ha! This would fit the description. So after I clean it all up and change the oil...I check the timing...framing...everything is spot on and clearly nothing had slipped (didn't need to loosen the shutter)...successive starts/stops...still dead on.

So, I ask them...do you see any ghosting? They said no but it was "side-to-side" ghosting! Now that was a key bit of information! Never mind their lack of terminology..."you mean the image was "mirrored?" "Yeah." Well that only happens if the image can reflect somewhere and it wasn't showing itself on target film or the green-band I was using. They then said...well it was only on some scenes! "What Lens?" "Scope" So I inspect the Scope lens....there was a crack on the first element...if the right image hit it at the right place...it could cause a reflection!

Always keep an open mind and try and get as much detail...such as it is, as you can.

Steve

| IP: Logged

Louis Bornwasser
Film God

Posts: 4441
From: prospect ky usa
Registered: Mar 2005

posted 05-31-2008 08:29 PM

Steve: I feel your pain. Louis

| IP: Logged

Sean McKinnon
Phenomenal Film Handler

Posts: 1712
From: Peabody Massachusetts
Registered: Sep 2000

posted 06-01-2008 10:14 AM

Dont get me wrong, I totally agree with everything you just said. Obviously if you or I were there we would have been able to tell if it were the bearings before we replaced them. I did list a few different things to check when I replied on the first page. It is as you know more difficult to trouble shoot when you are not there, and not able to get immediate feedback. It could have been the motor but I just thought it was more likely to be the other causes I listed. If I was there to see it maybe I would have ended up looking at the motor first if that was what the evidence suggested to me.

| IP: Logged

Kenneth Wuepper
Phenomenal Film Handler

Posts: 1026
From: Saginaw, MI, USA
Registered: Feb 2002

posted 06-01-2008 12:13 PM

When I was the director of television and AV at the local school district, I had a wonderful technician who did the maintenance on the studio and other gear. He would occasionally hit a tougher problem where he asked for my help.

He would begin by listing all of the symptoms and then begin to describe his trouble shooting steps. At that point I would ask him to stop as he had taken steps that were not successful in the repair and I did not want to be misled by his results.

I have also found that we often look for the most complicated causes to a problem while overlooking the obvious real cause.

I found the best approach is to take a film path, audio signal or mechanical chain and trace it from one end to the other in a systematic way. Output to input or the reverse. Sometimes you might have the luxury of substituting parts in the pathway to eliminate them as a cause. The "black box" technique or "board switch" in digital and electronics.

KEN

| IP: Logged

Sean McKinnon
Phenomenal Film Handler

Posts: 1712
From: Peabody Massachusetts
Registered: Sep 2000

posted 06-01-2008 12:53 PM

quote: Kenneth Wuepper
He would begin by listing all of the symptoms and then begin to describe his trouble shooting steps. At that point I would ask him to stop as he had taken steps that were not successful in the repair and I did not want to be misled by his results.

Wouldn't that cause you to waste time by going over and testing things that he may have already tested and ruled out?

| IP: Logged

Chris Slycord
Film God

Posts: 2986
From: 청주시, 경북도, South Korea
Registered: Mar 2007

posted 06-01-2008 01:17 PM

And doing otherwise he could possibly waste time too by trusting the other guy's results. Like if you assume X was ruled out, you start working on finding other sources of trouble. Then hours later he finds that the other guy didn't actually test X properly and wasted hours when he could've taken a few seconds/minutes of testing.

| IP: Logged

Louis Bornwasser
Film God

Posts: 4441
From: prospect ky usa
Registered: Mar 2005

posted 06-01-2008 04:01 PM

I have found (sadly) that you need to try everything yourself. Even thought you know and trust the other technician, you may well have a language or an understanding barrier. Assume absolutely nothing. Louis

| IP: Logged

All times are Central (GMT -6:00)

This topic comprises 2 pages: 1 2

Printer-friendly view of this topic

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.