8mm Forum: Elmo 1200D Projector Threading Problem

This is topic Elmo 1200D Projector Threading Problem in forum 8mm Forum at 8mm Forum.

To visit this topic, use this URL:
https://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=008321

Posted by Wayne Watson (Member # 3430) on June 30, 2013, 11:07 PM:

About six weeks ago, I had my projector serviced in the SF Bay Area. As it turns out, it only needed lubrication, and a general inspection. I live in the Sierra Foothills, and picked it up on a return trip after visiting some friends for 3 days.

Today I decided to try it and found I cannot thread film at all. The upside down film guide does not release properly when I try to thread the film. The typical procedure is to push the guide down to lock it. However, when I try to thread the film. the guide snaps up to quickly and the film continues on a horizontal path. Sometimes it goes along the guide, and gets stuck on something. The net result is the film gets folded.

Any ideas? I sure do not want to drive to the Bay Area to get this fixed.

Posted by Akshay Nanjangud (Member # 2828) on June 30, 2013, 11:23 PM:

Did you use the film cutter? Cutting a little bit of leader is necessary.

Posted by Janice Glesser (Member # 2758) on July 01, 2013, 12:35 AM:

The Auto-threading lever is not locking down. Bummer...I'm surprised who ever fixed it didn't try running some film through it [Confused]

You should open the front cover... Turn the motor selector switch to the loading position.
1. Check the black auto-threading release lever just above the level meter to see if it is somehow stuck down.

2. Check to see that the Orange reverse lever is not stuck down.

3. Next...Press down on the auto-threading lever a few times to see if it stays down by itself and observe the mechanism...

4. If the lever still won't latch... feed some test film into the projector while holding the auto-threading lever down until the film reaches the take-up real. If holding it down manually allows the film to thread properly, then you can use the projector and this will buy you some time until you can get the machine looked at again or perhaps someone here has a solution. I have some projectors that I have to hold the lever down and some I don't.

Since I live in the Bay Area I'm curious to where you took it for repairs?

Posted by Akshay Nanjangud (Member # 2828) on July 01, 2013, 12:45 AM:

I believe he took it here: Denevi. This is my guess. Gerald told me of this place.

Janice, Wayne is saying the guide locks down but comes up too soon. At least that is what I understood.

quote:
The upside down film guide does not release properly .....

Posted by Janice Glesser (Member # 2758) on July 01, 2013, 12:56 AM:

Same trouble-shooting procedure Akshay...something is triggering the release prematurely.

Posted by Akshay Nanjangud (Member # 2828) on July 01, 2013, 01:00 AM:

Speaking for myself, I never understood the mechanism connecting the black switch to the threading film guide after first sprocket. It doesn't seem to be visible on opening the back cover. Do we have a thread with pictures of this mechanism?

Posted by Janice Glesser (Member # 2758) on July 01, 2013, 01:10 AM:

No I don't Akshay. I just got my ST1200 and it's so far running fine so I haven't needed to dissect it yet [Smile]

Another thought Wayne...check the film path to make sure the gate is secured properly and that there are no obstructions.

Posted by Hugh Thompson Scott (Member # 2922) on July 01, 2013, 06:32 AM:

Hi Wayne,try just threading the film with a finger holding down
the green button on top,then when the end of the film appears,
take it off. Is the retactable guide locked back out of the way,as
this can be a bit of a bind, I since removed it on my Elmo's.
As Janice rightly says,make sure the end of the film is trimmed.
Also you might try some stiffer white leader,as this won't buckle
so easily for threading.

Posted by Wayne Watson (Member # 3430) on July 01, 2013, 10:31 AM:

Yes, Denevi. I used the cutter. Thanks for the instructions. I'll try them out.

Unfortunately, when I picked it up, the repairman wasn't around, so couldn't ask him to play it for me.

Denevi sure is in a tricky place navigationally. It's not obvious how to get back to the main highway between 880 and 680.

P.S. Too bad that when I try to respond, I cannot see the responses above mine. Ah, I see they are in a scrollable window below.

Posted by Dominique De Bast (Member # 3798) on July 01, 2013, 12:58 PM:

Just to let you the possibility to answer to your own topic ;-)

Posted by Wayne Watson (Member # 3430) on July 01, 2013, 04:41 PM:

Thanks. Now I can continue. :-)

Clipping the film did help, as did holding the auto-threader lever down. However, just trying to engage the lever takes a number of trys. It just jumps back up. If it is engaged, then it will jump up when I try to thread the film (motor running). If I have no film to thread, it will popup. That is, I cannot engage the lever. Perhaps the manual threader below the rear reel is at fault?

------------
Well, back again with new info. I can get the lever to stay down, if I really press hard on it. However, with the reel I'm working with, 200' reel of Star Wars, the film either shoots out horizontally, or ends up trying to loop under the lever.

Well, the Elmo guy is in on Tue to Thu, so I think I'll take it up with him.
[Smile]

Posted by Wayne Watson (Member # 3430) on July 03, 2013, 07:08 PM:

I finally got to the Elmo tech guy. We talked it through.

There's a solenoid (electro-magnet). involved. It is a cylinder with a small rod through it. The solenoid is on the inside. When a current is present the rod goes forward through a hole and locks the auto-threader on the other side. It is released (unlocked) when the film reaches the sprocket down at the bottom of the path of the film. It seems as solenoid isn't working.

The tech guy needs to do a little research to understand why the solenoid isn't working. Next week. Until then, I'll have to use manual threading.

Posted by Akshay Nanjangud (Member # 2828) on July 03, 2013, 07:24 PM:

I assumed this mechanism would be purely mechanical, you know, with linkages. But there is a solenoid involved.

Posted by Lindsay Morris (Member # 3812) on July 07, 2013, 09:21 PM:

Wayne,
A bit of info for you that may assist.

I also have a Elmo ST1200HD which has the same problem and previously had a ST1200 which worked fine so was able to compare on the bench just how the threading system works...and all that is NOT readily evident from the service manual on either.
When you press down the Green Threading device above the gate that action releases a spring loaded plunger which pops out of the tiny solenoid in behind it. It then stays latched DOWN until an electrical pulse is sent to that solenoid to attract that plunger back into the solenoid coil. Over time the weenie spring in there collapses or simply breaks up into a bundle of bits of fine wire OR as in my case the previous owner had the assembly out and lost the weenie spring which is a total swine to get back in there.
The electrical pulse to operate that solenoid comes from a set of contacts attached to the auto thread takeup reel guide as well as the Black lever that sits below the takeup arm (just above the VU meter).
All in all pretty simple and generally reliable until that spring collapses OR even the solenoid becoming sticky creates the problem you describe.
If your service guy has to replace that spring wish him luck as one needs many hands to get it all back together.

With the rear cover off and a good torch you can see the tiny plunger sitting in the solenoid coil and when you press down the auto thread unit a metal piece attached to that moves down out of the way of a vertical piece of metal attached to the solenoid plunger and the spring then is able to drag the plunger OUT of the coil tube and that vertical piece then LOCKS the auto thread unit down.
If you hold the auto thread down and use a small screwdriver you can flick the plunger forward which then should show the tiny coil spring around the plunger which is supposed to move the plunger out of the solenoid coil.
You might be lucky that it is only sticky/gunky & am not sure what you might have in USA that is used to clean printed circuit boards but a few squirts of that onto the plunger and moving it back and forth with the screwdriver MIGHT free it up for you.
Once operating correctly see if you can rub a bit of graphite from a pencil onto what surface area of the plunger you can get at to assist lubricating it.
DO NOT use WD40 or similar solvents as they only make the problem worse.

[Roll Eyes]

Posted by Wayne Watson (Member # 3430) on July 10, 2013, 07:22 PM:

Hi, thanks for the info. Do you have any idea how many springs are in the enclosure?

The fellow at Denevi is nterested in this problem. He's never seen it before. He has an Elmo in shop for comparison. He's going to look into it when he's finished, which will probably be next week.

In the meantime, if I really need the auto feed, I can just hold down the lever until the film starts to be drawn in by the take-up reel.

Posted by Lindsay Morris (Member # 3812) on July 11, 2013, 03:22 AM:

Wayne,
There is only one spring in there and is about 3 turns of wire around 0.5mm in diam wound around the plunger shaft diam of around 4mm.
It is all held in place with a tiny pin that also attaches the vertical piece of metal to the solenoid plunger with the vertical piece pressing against the plate attached to the Auto Thread lever.

Getting the 2 tiny screws out that hold the solenoid in place is difficult as your have to remove a couple of the gears nearby to get a good firm connection onto the 2 solenoid holding screws without damaging the heads.
Getting it back in is tricky holding the solenoid in place and getting a screw to start without cross threading or dropping out and down into the machines bowels.
Patience needed. [Smile]

Posted by Wayne Watson (Member # 3430) on July 11, 2013, 04:28 PM:

I forget to mention that I counted three.

UBB.classic^TM 6.3.1.2