Film-Tech Forum ARCHIVE: Simplex 35 Speed Issue

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Posted by Chad M Calpito (Member # 3736) on 05-27-2008, 10:41 AM:

Hi all. Well, last night while doing my booth shift, I got a report from my opening projectionist that he got a complaint of a sound problem with projector #9. I was told it was in reel #4 of Expelled. Now, I've had this print for at least a month without any sound problems on this print.

So, during the next show, I do a series of troubleshooting by listening to the movie via the auditorium and the booth monitor speaker. I even look at the projector while running and I noticed that as the film goes down to the soundhead from the intermittent sprocket, it will bulge out for a few seconds, then return to normal and then bulge out again.

I also checked the motor to see if it was hot and was normally and there weren't any strange noises or burning smell from the motor. I had my manager come up and look at it and he was confused by it as well. The motor, itself, is new.

Anyway, the sound runs normally, then, it slows slightly and returns to normal. What could cause this problem? Could it be a belt inside the projector?

Oh yeah, the projector also has a 5-Star Soundhead as well. Here is some information about the system: Simplex 35 (non-Turret) with the 5-Star Soundhead, Christie SLC Lamphouse w/ AM-10 Automation and a Christie AW3R Platter.

I hope I described the problem good enough. Any ideas would be helpful. Much Thanks!

Posted by Sean McKinnon (Member # 612) on 05-27-2008, 12:30 PM:

It could be seizing bearings in the soundhead, it could be a worn or damaged gear on the soundhead or the bottom of the vertical shaft. It could be the sound drum bearing or the damping roller, It could be the coupling between the soundhead and the projector head. If you do not know how to check these things I would call in a qualified technician to check things out. If you a penthouse reader for digital sound on this screen you should be able to run in digital until you get things fixed. I will give you a warning though if you to choose to continue to run with the machine like this you could further damage the machine, or the film. A simple repair could turn into a more complicated and costly one.

Posted by Chad M Calpito (Member # 3736) on 05-27-2008, 01:52 PM:

Last night, after my manager saw it, he informed me he'll call our Technician to look at it. Luckily, last night was the last time we would be using the projector until the weekend.

Anyway, I am hoping that it will get fixed ASAP since I'm unqualified to repair it at this level. I do agree that if continued running in it's current condition that things will get worse and more costly.

Thanks for the information, Sean. Much appreciated. [Smile]

Posted by Mark Gulbrandsen (Member # 72) on 05-27-2008, 03:14 PM:

If the 5 Star has a Bodine motor I'd suspect that before anything else!

Mark

Posted by Steve Guttag (Member # 268) on 05-27-2008, 04:24 PM:

If it is the motor, you'd see it on screen as the flicker from the shutter would also be changing plus you would likely hear the motor changing pitch.

Bad bearings on the sound drum would cause what you describe. If the motor is indeed speeding/slowing...then yes it could cause what you describe.

If the motor is found to be the culprit...check the switch and/or relay that is controlling it as it may be failing and causing the motor to run erratically.

Steve

Posted by John Hawkinson (Member # 1135) on 05-27-2008, 05:26 PM:

So, if you have a new motor, the obvious question to me is...why? What caused the old motor to fail? Has that been corrected?

--jhawk

Posted by Louis Bornwasser (Member # 3063) on 05-27-2008, 06:44 PM:

I'm bettin' on the bearing, myself. (Cheap!) Louis

Posted by Chad M Calpito (Member # 3736) on 05-27-2008, 10:02 PM:

What I was told about the motor was changed out and that happened before I was fully transferred to the Gaslamp 15. In essence, I was told it was fairly new.

Unfortunately, I didn't check to see if it was a Bodine motor last night. Currently, at this point, I won't rule anything out. I called the theatre this afternoon and my technician will be in tomorrow.

As far as on-screen flicker, I didn't see any on the screen. So, the picture was good.

In answer to your query, John, I don't know the exact details what caused the old motor to fail. I'm gonna have to try and dig up some maintenance records on #9 to see if I can see why it was replaced and such.

Anyway, I hope to have an update for all of you soon.

Posted by Mark Gulbrandsen (Member # 72) on 05-27-2008, 10:06 PM:

On screen flicker might not be that noticable depending on how much it actually slows down and how bright the image is on the screen. It could also be a bearing starting to drag as Louis says... the rear rotary stabilizer bearings fail alot on those soundheads... The crap from the belts gets into the bearings.

Edit: I'll rephrase this... All the bearings on 5 Stars fail alot. If you do install new ones try to use rubber sealed bearings on the drive shaft and idler but use only shielded bearings on the rotary stabilizer and lateral guide shafts.

Mark

Posted by Steve Guttag (Member # 268) on 05-28-2008, 08:18 AM:

Mark, the thing that would key ones key to the flicker is that the speed would be changing. If something is very even with a uniform period, you will adapt. However, once the period changes or is inconsistant, it becomes quite noticable.

As to the bearings...I don't have that much problem with the bearings on the 5-star with the system that has been in use for the last 20-years. That is, the round-tooth belt system. Now with the square tooth system, yes, the idler pulley bearings (P-3368) were so horribly loaded they would often fail and the P-7015 bearing in the black bearing bracket is very poorly designed (no outside support of the shaft).

We have generally sourced our bearings from good manufacturers and don't tend to have the problems with them.

One problem we have had is from the rubbing alcohol users out there (for cleaning)...it will kill any bearing by wicking its way into the bearing, letching out the lubricant and then leaving its water behind to oxidize things.

Steve

Posted by Mark Gulbrandsen (Member # 72) on 05-28-2008, 08:51 AM:

Steve,

A couple of fps slowdown may be difficult for the average Joe to perceive especially on a poorly lit screen but it will be very obvious in the sound.

With bearings you will see the opposite in areas that have a very dry climate... Areas with higher humidity don't see as much bearing failure... I didn't see all that much faliure back in the Midwest due to dry climate. I blame it on the bearings that Wrong used. Cheap 2 buck bearings from Singapore that only had shields. Even Christie learned a long time ago that sealed bearings were necessary but Wrong continues to install shielded bearings in critical places that could take a dollar more expensive sealed bearing. The other problem with the 5 star is the alumnium pulleys. Round teeth or not in grind situations they wear in just a three or four years time and develop ridges around the outer diameter just like the P-35 alumnium pulleys do. The ridge then chews away at the belt and the resultant belt crud gets into the stabilizer bearings. Until I got almost all the 5 stars in this neck of the woods switched over to sealed bearings on the idler and drive shaft I used to see so many failures that I carried all the bearings, idler, and drive shaft in my sound service kit rather than have to run out to the van to get em. I agree that only good quality bearings should be installed!! The failures I see now are mainly rotary stabilizer bearings since they can't be sealed and thats just once in a while, occasionally still an idler because the bearings are undersized (and always have been) none the less they still do fail often enough that I still carry em in the van.

Mark

Posted by Chad M Calpito (Member # 3736) on 05-28-2008, 09:58 AM:

The light image on screen from #9 is nicely lit. We are using a 3K Christie Xenon Bulb.

Posted by Steve Guttag (Member # 268) on 05-28-2008, 10:09 AM:

I have zero doubt that the climate difference has a great affect on how the mechanicals behave. I have a hard time convincing people that the use to tin plated connectors out here in the humid areas just fail (they go noisy first).

As to Strong's aluminium plullies...I don't think I've had a single round tooth pully fail on the soundhead proper. Perhaps a motor pulley here and there...but probably more motor's (Bodine) than pulleys.

I have not taken to sealed bearings as of yet as a rule but I don't doubt that they could help with keeping crud out...that is their job. Then again, I don't see that much curd around the bearings on the round tooth systems. We get good belt life too on the round tooth.

Steve

Posted by Sean McKinnon (Member # 612) on 05-28-2008, 10:37 AM:

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?

Posted by Scott Norwood (Member # 30) on 05-28-2008, 10:45 AM:

If one has this issue and determines that bad bearings are the cause, how does one decide whether to replace the bearings in the roller or the ones in the drum shaft?

I had a similiar issue (excessive flutter in soundtrack) with an SH-1000 and a technician correctly determined that the bad bearings were in the roller assembly. How did he know? In any case, this was an easy and not-very-expensive fix.

As for the 5-star belts, do people replace these on a regular schedule, or just when they begin to show cracks? (The ones that I'm familiar with are in 1998-vintage 5-stars; I don't remember if these have square or round teeth.)

Posted by Darryl Spicer (Member # 711) on 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.

Posted by Steve Guttag (Member # 268) on 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

Posted by Chad M Calpito (Member # 3736) on 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.

Posted by Sean McKinnon (Member # 612) on 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.

Posted by Steve Guttag (Member # 268) on 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

Posted by Louis Bornwasser (Member # 3063) on 05-31-2008, 08:29 PM:

Steve: I feel your pain. Louis

Posted by Sean McKinnon (Member # 612) on 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.

Posted by Kenneth Wuepper (Member # 1174) on 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

Posted by Sean McKinnon (Member # 612) on 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?

Posted by Chris Slycord (Member # 4239) on 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.

Posted by Louis Bornwasser (Member # 3063) on 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