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Topic: Elmo ST-1200 Delay in Motor Starting

Janice Glesser
Film Goddess

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From: Sunnyvale, CA USA
Registered: Sep 2011

posted June 18, 2015 10:37 AM

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When cold the motor on this projector has a delay in starting. I usually have to turn the main switch to "S" (Still) first (a couple of times) to get the motor turning...then turn it to "F" (Forward) to thread the film.

Frank Arnstein mentioned having the same annoying problem.

quote:
Curiously enough Janice, my Elmo ST 1200D is doing exactly the same thing and I don't like it very much.
When cold, there is an unexplained delay of a few seconds before the motor actually spins. Once its made the first start for the day all seems fine till its cold again and it then reverts.

Have just replaced the a/c motor capacitor but I can't tell yet if its fixed. Will now recheck all the belt tensions and also try oiling the end bush on the motor.

Has any member with an Elmo ST 1200 experienced this baffling delay on cold start and why is it so?

This is the question which more and more members are asking themselves. Time will tell if anyone discovers the cure.

I'll try and get a video posted so you can see the issue. Hopefully someone will have a fix suggestion.

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

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Steve Klare
Film Guy

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From: Long Island, NY, USA
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posted June 18, 2015 10:50 AM

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Hi Janice,

I've seen more than a few times where the motor actually turns a second or so before the roller grabs on the shutter wheel, but it sounds to me like you are saying the machine is just stone still and quiet.

I have to guess based on my other Elmos, since I haven't had this part of my own ST-1200 apart, but there are probably some lever switches activated by a cam on the control knob shaft. (There's one for the lamp too.)

Multiple tries to get anything to happen could mean a switch that controls your motor is going flaky.

In your circumstances I'd put a voltmeter (AC scales) on the motor and watch what happens to the voltage when you have one of these awkward pauses!

Safety First: If you go poking around with that back cover off, lethal voltages are present!

(Connect up with the machine unplugged, disconnect the same way. Keep one hand in your pocket if you want to be really safe!)

--------------------
All I ask is a wide screen and a projector to light her by...

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Tom Photiou
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From: Plymouth U.K
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posted June 18, 2015 03:02 PM

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If the belts were sticky at any point when these projectors are cold the residue within the 18 and 24fps pulley grooves acts like glue, once its broken from cold its usually ok during the rest of the show. Then when its cold again it does it again.
To prove this point before you start up from cold remove the back cover, manually turn one of the two rubber wheels, (this will break the sticky jam), then switch the machine on, if spins on the first position then this is the problem. We had it years ago. I simply had to remove all the belts, use a good quality clean on a skinny cotton bud and clean deep inside all the belt pulley grooves as well as the belts themselves, even if you have put new belts on they will pick up sticky residue left in the grooves etc. [Wink]

[Wink]

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Janice Glesser
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From: Sunnyvale, CA USA
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posted June 18, 2015 03:26 PM

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@Tom...I had this problem with all the belts off also.

@Steve... After just replacing a micro switch on my Sankyo 600, I'm wondering if the micro switch might be going bad in this case too.

Here's a video of the problem:
https://youtu.be/jc0TF7yrxzI

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

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Tom Photiou
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posted June 18, 2015 04:36 PM

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weird! i'll take a look in the service book to see if this fault is listed

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Steve Klare
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posted June 18, 2015 04:58 PM

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That hum means to me your motor is getting power, so maybe not a switch...

You just replaced the belts. Is it possible the idler pulley on the motor belt is too tight and maybe the tight belt is stalling the motor?

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All I ask is a wide screen and a projector to light her by...

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Andrew Woodcock
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posted June 18, 2015 05:17 PM

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Steve's bang on I reckon Janice. It simply sounds that the motor has stalled due to being too heavily loaded onto the shutter wheel. It sounds like the motor doesn't have sufficient starting torque to overcome the heavy load caused by the friction. Once the shutter wheel drive chain has turned very slightly then the load will become drastically reduced on the motor, and it then will accelerate very quickly up to full running speed just as the video endorses.

This explains when going back to switch position one why the motor isn't simply just driving the lamp cooling fan as it should in the first position of the switch as this is only meant to be the still frame position

The way to prove this theory is simply remove the drive belt which is very easy to do on these and then see if the motor runs instantly when either switch position is selected.

If this does prove to be the case, you will need to adjust the clutch height position so less friction and force is placed on the shutter wheel by the rubber drive wheel on the clutch mechanism.

Please refer to my recent posting to Frank regarding this adjustment.

On many ac motors the starting torque can become greatly reduced over the years by overloading regularly and damaging the rotor through overheating.
Once you have your machine running perfectly, try to avoid cleaning films on rewind etc etc for the reasons suggested above and also to keep your spindle friction linings and clutch mechanism healthy and preserve its lifespan.

--------------------
"C'mon Baggy..Get with the beat"

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Steve Klare
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posted June 18, 2015 05:50 PM

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Yep!,

I replaced a drive belt on my mom's washing machine once, and tightened it as if it was a fan belt on a car. (You go with what you know.)

-made that exact same sound!

(Just moreso...)

--------------------
All I ask is a wide screen and a projector to light her by...

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Janice Glesser
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From: Sunnyvale, CA USA
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posted June 18, 2015 06:28 PM

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Steve and Andrew...I don't know if you saw my comment to Tom...but I've had this problem since I first got the projector and it didn't have any belts on it.

The 5 belt set I bought is probably the same one you got Steve. It has 2 belts for the clutch rollers - one large and one smaller. I'm not sure why the smaller belt is needed?

I'll remove the belts and test it again in a couple of hours.

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

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Andrew Woodcock
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posted June 18, 2015 06:36 PM

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in that case then Janice, check the Rotor is free turning with everything removed. Other than that it may well be the starting capacitor that requires change out as it relies on this just to provide a phase lag and therefore a phase shift just to get the thing going. Beyond that the rotor will be damaged beyond repair and you would need a healthy replacement motor (but keep your old one as the stator windings are clearly good and therefore you could always use this again if your other motor windings were to fail).

--------------------
"C'mon Baggy..Get with the beat"

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Janice Glesser
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From: Sunnyvale, CA USA
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posted June 19, 2015 11:13 AM

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OK guys...here's the status. I removed the belts last night and this morning the motor started up right away. This is a good sign that there isn't a problem with the motor, but as you suspected it's the drag from the belts. My intitial starting problem without the belts was probably due to the motor not being run for a long time.

Anyway...Looks like my next step is the clutch adjustment stage and although Frank was very clear on your instructions Andrew...I'm not. My confusion is partly to my dyslexia and partly to just not being able to follow engineering terms yet. [Confused]

[Confused]

I have the diagram from the service manual, but things just don't look the same to me.

In looking at page 10 of the service manual under "ASSEMBLY"...instruction (4.) says:

quote:
"If Clutch unit assy could not convey the rotation of Motor assy during 18 f/s or 24 f/s projection, loosen attaching scres (Fig.10-5) or attaching nut (Fig. 10-6) and adjust the position of Clutch link adjuster and Clutch lever (2) assy."

Is this the adjustment you are recommending Andrew that I need to do?

To maybe help me out...I've taken a picture of the clutch area in hopes you Andrew or Frank can point out what needs to be removed and adjusted. I can add pictures in stages to illustrate the procedure. One thing I noticed is that the spring that Frank mentioned... shown in my picture ... isn't even shown in the diagram.

[ June 19, 2015, 01:27 PM: Message edited by: Janice Glesser ]

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Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

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Antoine Orsero
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From: marseille france
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posted June 19, 2015 01:21 PM

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I have the same problem with one of my two projectors! I replaced the starting capacitor, but the problem is the same.
Even when I set the start pause button, you hear a buzzing noise and after a while it starts!
I'll try to remove the belts

--------------------
Tony

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Tom Photiou
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From: Plymouth U.K
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posted June 19, 2015 01:35 PM

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If,when the belts are removed, it starts immediately I'm 99.9% positive that its not much more than a stickiness within the belts/pulley system. I have had exactly the same problem twice with two different 1200s and although i did replace the belts with genuine Elmo belts after a week or so they began to stick when cold until i turned the switch on and off a few times, this was simply due to the residue of old belts being picked up. I used a good powerful cleaner on all the belts and pulleys and it worked on both occasions. i got the hum of the motor which if left too long wont do it any good.
Please let us know if you do find another fault causing this as i will be very interested in this fault/problem. [Wink]

[Wink]

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Janice Glesser
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From: Sunnyvale, CA USA
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posted June 19, 2015 02:26 PM

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Tom...these are new belts (very smooth and dry) and I've cleaned all the old belt residue off the metal pulleys... so I really don't think stickiness is the problem here. Either the belts are too tight or the clutch rollers are pressing too hard against the shutter wheel...it could also be a combination of both.

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

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Andrew Woodcock
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posted June 19, 2015 02:58 PM

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Adjustment will be necessary Janice if you have removed the shutter belt. It will,like most adjustments, be a trial and error exercise until you find the point where the clutch drives the shutter wheel ONLY in switch position 2 and with just the correct amount of friction so the projector turns instantly and at a constant speed without slippage.

You have to loosen screws 5 in the diagram from the service manual then raise or lower the cam track along its elongated slots before tightening screws 5 once again.

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"C'mon Baggy..Get with the beat"

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Steve Klare
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posted June 19, 2015 03:20 PM

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This is the greatness of this forum:

My own ST-1200 is recovering from surgery and just as I am getting ready to stitch it up I'm learning all this useful stuff!

My own roller assembly is dismounted right now. I adhered the new shutter belt in place and I'm 24 hours into the 72 hour maximum set time the cement packaging specified.

(It's been dead since March...why hurry now?)

For you Eumig fans: When the Tank had to go out sick, My Eumig/Bolex 800 series machine came off the bench and has been doing a great job. I think I'll keep it active after my 1200 is fixed.

--------------------
All I ask is a wide screen and a projector to light her by...

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Janice Glesser
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From: Sunnyvale, CA USA
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posted June 19, 2015 04:48 PM

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I understand that there needs to be an adjustment. GOT IT! My question is....according to my picture (not the diagram since I'm having trouble associating the diagram with the actual parts)... Looking at my photo of the clutch what do I need to do next? I don't want to remove anything until I know what I'm doing. Is the adjustment screw accessible without removing something? OR...If I need to remove something please point out the exact screw(s) to do this. I'll take a second photo of the adjustment screw when I've located it. This may seem very obvious to you guys...but not to me. I need help to document this process with pictures and annotations. I think this will also be helpful to others with this projector.

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

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Andrew Woodcock
Film God

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From: Manchester Uk
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posted June 19, 2015 05:24 PM

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It's been a while Janice as my love for the St1200 ended quite some time ago, but from memory I removed the clutch assembly completely each time I made an adjustment to the cam track just to gain access to the screws on cam track labelled 5.

If my circumstances were different right now Janice, I would have spent much longer doing the work and posting pictures etc.
I am sorry Janice but I just don't have very long each day at the moment to spend on film or projectors however my interest and love for both never falters.

Though I wasn't able or willing to post photographs on here at the time, I am certain I would have written about the topic in greater detail at the Times I carried out this work so if you do some historical back tracking on here Janice at the time I did what you're doing now, hopefully you'll gain a full understanding of the situation. [Smile]

[Smile]

[ June 19, 2015, 06:34 PM: Message edited by: Andrew Woodcock ]

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"C'mon Baggy..Get with the beat"

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Janice Glesser
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posted June 19, 2015 09:47 PM

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OK Andrew...thank you for your input anyway. Now...Is there anybody else willing to take a stab at explaining how to remove the clutch unit to get to the adjustment screws?

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Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

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Steve Klare
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posted June 19, 2015 11:06 PM

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Hi Janice,

I'm going to be looking into that myself the next couple of days.

I'm hoping the adjustment is possible with everything installed because it will get nasty if it isn't.

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All I ask is a wide screen and a projector to light her by...

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Janice Glesser
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posted June 20, 2015 01:11 AM

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Steve...I think this will help. Here's another angle looking straight back into the clutch area. This looks more like the piece in the service manual diagram. I've pointed an arrow to where I think the Fig. 10-5 screw is. It would seem to me that you could just use a long screw driver to reach into those screws and not have to remove anything. However, I'm still not sure what to adjust if that screw is loosened.

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Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

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Andrew Woodcock
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posted June 20, 2015 03:59 AM

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Yes that's it Janice, so if you can do the adjustment in situ,then that's obviously the easier and simpler option.

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"C'mon Baggy..Get with the beat"

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frank arnstein
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posted June 20, 2015 06:21 AM

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Hi Janice..

You said....."I understand that there needs to be an adjustment. GOT IT! "

I say.... "Going by what I see in your video, it doesn't need adjustment so don't bother."

Janice, tell me, why do you start your projector in the manner seen?
You go from OFF, and then skip the important position 1, to go straight to 2.
Don't do that Janice as its bad for the motor. You are actually helping the motor to stall.

If the motor doesn't start spinning with the fan on position 1, then don't go to position 2. Stop and wait there till it spins.
It will have absolutely no hope of turning the shutterwheel until the motor is spinning at full speed and it can only get up to speed if its not touching the shutterwheel.
So that's position 1. Motor spinning, drive wheel clear of the shuttershaft. Also the fire shutter will be automatically deployed, designed to protect stationary film frames from burning if caught in the light beam.

Now is the time you can move to position 2 or project.
The already spinning driving rubber wheel is now allowed to drop onto the edge of the shutterwheel. The extension spring helps pull it against the shutterwheel.
Now the drive wheel is easily able to turn the shutterwheel as it already has full momentum.

As I can see on your machine, once its spinning, its quite capable of turning the shuttershaft normally.
So don't mess with the adjustments if its not needed Janice.

Then that leaves the question, " If its clear of the shutterwheel, why won't it spin instantly?"

1. It could be Motor belts are too tight preventing the motor starting to spin due to too much friction generated.

2. After years of being idle, the sliding bush at the outer end of the electric motor may be dry or even tight, thus preventing normal startup of the rotor. This bush needs to be oiled and eliminated as a possible suspect. Put a few drops of fine oil on the bush and try to run it in.

3. The motor starter capacitor has failed so it wont start turning. I don't think its that as I replaced mine and it made no difference.

4. It could be that the electric motor has been damaged by too much stalling of the rotor when previously attempting to project. This can leave its starting torque much diminished permanently, but it may still get up to normal speed once running. If you cannot overcome the low start-torque issue and it becomes a constant pain, the cure is to replace the motor .

See what you all may think about the above rambling.

dogtor frankarnstein.
[Smile]

[Smile]

[Roll Eyes]

[Confused]

[ June 20, 2015, 09:13 AM: Message edited by: frank arnstein ]

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Andrew Woodcock
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posted June 20, 2015 08:09 AM

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Great points raised there Frank. I hadn't watched the video as carefully as I should so didn't know switch position 1 was being ignored. [Smile]

[Smile]

Frank is right of course, adjustments should only be made when it is necessary after all these are factory settings that ordinarily never need revisiting. However when shutter belts have been removed I would have thought the difference in diameter would have deemed it necessary, as in this case.

Whenever i have made these adjustments and adjustments to the diffuser mechanism, it was always when I first got the machines as they weren't running correctly to begin with.
In many cases the diffuser didn't move at all when I got them as the cam mechanism which can be quite finicky, was misaligned.
Once the adjustments had been made I have never had to do it again on the same machine.

Hopefully Frank you now have your still frame function back now in switch 1 position?

--------------------
"C'mon Baggy..Get with the beat"

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Janice Glesser
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posted June 20, 2015 01:14 PM

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Hallelujah Frank!!!! Thank you! Finally some feedback I can get my teeth into [Smile]

[Smile]

I was up until 1:00am this morning trying to analyze and locate the parts that may need adjusting. Although not as detailed as you have presented Frank...I was coming to some of the same conclusions. I couldn't see where any adjustment of the clutch would solve the delay in the motor starting.

As far as "Why" in my demo video I started it in position 2...I was just following the Owners Instruction Manual. I don't think I've ever had to start a projector in the "Still" position before.

I'm going to start with your first and second suggestions.

1. "It could be Motor belts are too tight preventing the motor starting to spin due to too much friction generated."

I've already tested it with both motor belts removed and motor/fan start up fairly rapidly. Last night I tested it with only one belt installed. There was some delay, but the fan started and the motor got up to speed much quicker than with the 2 belts. I'm going to try making a belt with some belt material I have. It will be a round belt, but I'll see if a looser belt helps.

2. "After years of being idle, the sliding bush at the outer end of the electric motor may be dry or even tight, thus preventing normal startup of the rotor. This bush needs to be oiled and eliminated as a possible suspect. Put a few drops of fine oil on the bush and try to run it in."

The fan sits up against the left side of the motor. So by the outer edge do you mean the bush is on the opposite end to the right? I see two locations with holes there... Arrow 1 and Arrow 2. Is it one of these holes I should drop-in some oil?...or some place else?

[ June 21, 2015, 10:44 AM: Message edited by: Janice Glesser ]

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Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

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