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Author
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Topic: Eumig 900 series repairs and tips
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Paul Adsett
Film God
Posts: 5003
From: USA
Registered: Jun 2003
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posted January 08, 2017 01:44 PM
Anyone who owns a Eumig 938 stereo projector, or any of the non-coaxial reel design 900’s, knows that the automatic threading system works flawlessly 99% of the time. So when my 938 refused to thread any of my films, despite re-trimming and straightening the leaders, I knew something had gone seriously wrong. It did’nt take long to track down the problem.
The automatic loop forming on the 900’s is all mechanical, controlled by a complex system of cams on the control knob, and cam followers integrated into the loop formers. The problem with my machine was that the plastic cam follower, which is part of the inner bottom loop former, had simply snapped off. And it’s no wonder, the plastic arm which engages the cam is a thin plastic beam only 2mm thick! Exactly the same happened on one of my Eumig 926 GL’s, so I believe this is a part that is likely to have failed on many of the 900 series machines. Eumig were incredibly brilliant designers, but unlike the very solid build of the 800 series machines, the 900 series machines (although much better performers) featured many flimsy plastic components.
I thought my 938 was done for, since there is no way to manually thread these machines ,and the prospect of dismantling and reassembling that complex cam system is extremely daunting to say the least.
Since the threading problem was due to the rear side of the bottom loop former now being way too forward for the film to enter into the guide, I fitted a rubber band around the knob of the loop former and stretched it back over to the knob on the sound capstan shaft. This pulled the loop former back to its correct position for threading. Low and behold, I found it worked like a charm, and faultless threading was restored. Not liking rubber bands, I then decided to fit something more elegant, and found a tension spring which does the job perfectly. The spring hooks over the knob on the loop former and lies over the top off the sound head block, hooking over back edge of the metal plate.
One annoyance of the 900 machines is the need to use a screwdriver to remove the cover every time you want to clean the gate. Why Eumig did not use a knob instead of a screwdriver slot is beyond me, but here is a simple fix. I found that a standard automobile tire valve cover can be pressed over the head of the screw, and can be epoxied in place. You may have to file the plastic head of the sleeve on the bolt very slightly to get it to fit. Now , I can spin off both the cover screws on the 938 in a couple of seconds, with no searching for a screwdriver. It really is a much better way to do it.
One thing I like better on the 926 GL than the 938, is the cover. The GL cover is very attractive with the gold and black 2-tone finish and the embossed Eumig decal. It also seems to be a much more solid cover. Well, the 926 cover fits perfectly on the 938, and I think it makes the machine look great:
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The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj
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Paul Adsett
Film God
Posts: 5003
From: USA
Registered: Jun 2003
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posted January 10, 2017 11:16 AM
Hi Edwin, yes I certainly agree that the Eumig 938 is a fine machine, and the sound quality is amazing.
As I said, I suspect that there are a lot of 900 series machines around, all with broken plastic arms on the lower loop former, and therefore unable to thread any film. Both my 926GL and 938 stereo have this problem. The spring I added is the best kind of reasonably successful fix that I have come up with, but a new manufactured part, possibly using some strengthening filler, would be a much better way to go.
Here is a photo showing the breakage point of the plastic arm, which is a feature of the lower inner loop former part (labelled in the photo above):
And here is the piece that broke off:
This arm is only 2mm square section, and the back has a small cylindrical feature 2.5 mm dia and 1mm high, which projects out from the surface to engage into the slot in the rotary cam. I suspect it broke while I was pushing down on the loop restorer knob, while running a film ( yes this little beam section has to bend when you depress the loop former!
Another part that seems to consistently fail on these 900 machines is the main switch. I have had three 900 machines where the switch has frozen up and burned out. I have not been able to find any replacements and had to resort to mounting a rocker switch on the rear of the machine:
While I have your attention Edwin, I see that you manufacture replacement worm gears for these 900 machines. The worm gear on my 926 recently broke up, how difficult a job is it to replace it? :
[ January 10, 2017, 12:26 PM: Message edited by: Paul Adsett ]
--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj
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Paul Adsett
Film God
Posts: 5003
From: USA
Registered: Jun 2003
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posted January 11, 2017 07:08 PM
Excellent video Edwin! I had no idea what would be the best way to undertake this repair, but having seen the video I now feel that I can do the job. So, I will soon be ordering up a new worm gear from you for my 926GL.
One question, do you recommend greasing this gear, or not?
Andrew,
I wonder if an X-RAY of the head would be helpful in re-engineering it?
--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj
| IP: Logged
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