GS 1200. The rear arm is very slow.

[Melvin England]

Hi everyone.

I have never hidden the fact that I am not a technical / electrical wizard and that once a problem arises on a projector, then that is me totally stuffed.

A problem has arisen on my GS1200. The rear take up arm is moving very slowly resulting in the film ending up on a pile on the floor.
I did read the technical advice in the section that Doug compiled. Is it true that there is a separate power source that is reducing the power to the rear arm "engine" for use of a better word? In the example from many years ago regarding Alan Rik, I believe, there is something mentioned about the power being reduced from 7 volts to 3 volts to the arm thus not providing the strength to keep it taught. The repair involving replacing components is way way beyond me.

Is this the case, or is there possibly another reason, together with an easier solution that I am unaware of ? The net result is that until I can solve the problem, there will be no more 1200' presentations or optical features for the time being.

As the Beatles once said....... "HELP!"...........please!!!

[Graham Ritchie]

Its been a few years now since I carried out this work Melvin on a GS1200, to date its still running fine with no repeat problems with the take up..

[Melvin England]

Thank you soooo much, Graham, for that demo film which I have just watched.
It appears that, even for non experts like me, it is a completely DO-able job.

The only bit that concerned me was the liquid used. Is it available in a chemist shop? Is it a sort of distilled water ? Would tap water suffice making sure it is completely dry before use ?

Once I have this answer, I will do the job and let you and everybody else know how I get on.

Again, thank you for all your help.

[Graham Ritchie]

Hi Melvin

The most important thing is to take your time doing it and be very careful when you remove the back cover of the motor with its two brushes. Just work it of slowly. The brushes may have cut a grove for themselves over time into the commutator, so just carefully wiggle it of. When fitting I used a couple of cotton buds with there ends cut off to gently compress the brushes so they will start to slide onto the commutator, once those brushes are just on, then the brushes and the motor back cover can safely slide the rest of the way.

Its tricky but it can be done, as I say just take your time and don't force anything. I used this product its non-flammable and in my book that's a big plus.

The thing is the commutator gets gummy over time and contact between the brushes gets poor, also its important to get the build up of deposits between each segment removed once again carefully with a thin blade to scrape between them. There will be a day that the wear is such that a motor replacement will be the only option but hopefully by doing this with give you a few more years out of it. Try just doing you take up motor first, I did both as both those motors are wired up that if you have a problem with one it can affect the other, in saying that just try that take up motor first and see how you get on, it might be doing the one motor is enough. What I did is basic motor cleaning something I did on generators as a motor mechanic light years ago. In that case it includes some lathe work as well, not in this case though

[Matthieu van der Sluis]

Thanks for the link to this video.
only my reel just stops after a short whil, so if it is this, or needing to swap the gear?
The video is clear so this I dare.

[Matthieu van der Sluis]

Is this the same for a model MK3?

[Thomas Knappstein]

Hi Matthieu!

First you have to check out, where the failure comes from. If there is a cracked Gear you can hear it when the Motor is running. It makes a klacking noise.
If the Motor is dirty inside you have to be very careful because in the last MK3 Machines Elmo has changed the Motortype. If you have this Motors it is a little bit more tricky to open them because they have another Kind of Brushes. The third Thing is the Motor control Board for this Motors. It could be, that the tension ist to low adjusted and with a dirty Motor it will stop after 100meters on the take up Reel. You can turn up the tension with the little trimpoti ubove on the Board near to the rewind Motor. Here are a few Pictures of the Motor from the very last MK3 Machine. On one Picture you can see the three Pots on this little Board near the Rewind Motor. The upper one is for take up. The one in the middle is for rewind projetion and the one down is for the little swich in the green Guide. Try to adjust the upper poti first.

[Matthieu van der Sluis]

Hi Matthieu!

First you have to check out, where the failure comes from. If there is a cracked Gear you can hear it when the Motor is running. It makes a klacking noise.
If the Motor is dirty inside you have to be very careful because in the last MK3 Machines Elmo has changed the Motortype. If you have this Motors it is a little bit more tricky to open them because they have another Kind of Brushes. The third Thing is the Motor control Board for this Motors. It could be, that the tension ist to low adjusted and with a dirty Motor it will stop after 100meters on the take up Reel. You can turn up the tension with the little trimpoti ubove on the Board near to the rewind Motor. Here are a few Pictures of the Motor from the very last MK3 Machine. On one Picture you can see the three Pots on this little Board near the Rewind Motor. The upper one is for take up. The one in the middle is for rewind projetion and the one down is for the little swich in the green Guide. Try to adjust the upper poti first.

Ohh, saw this post too late.
I already ruined my motor.
I cannot get the back on the motor agaon and a tiny square thingy fell out, i think of one of the two brushes on the back.

Reading this, it might had helped.
There was no clicking sound and the real stopped at around 100" at first, but later it got worse and this morning almost right away.

[Thomas Knappstein]

Hi Matthieu!

Make some Pictues from inside of your ruined Motor please. Perhaps it could be repaired.
Have you take the Motor with the Gearbox out of the Machine?
To take this Motor out of the Projektor you must lie it on his Face with a Distand Block for the Focus Knob. There should no Weight on this Knob.
Then unscrew the 4 Screws of the Transformer and the Screws of the Motor Gearbox and the little conecting Board with the Wires. Now you can put the Transformer a little bit to the left side and get the Motor out of the machine. At last unsolder the blue and red Wire from the little conecting Board.

[Graham Ritchie]

Sorry to hear that Matthieu I never new there was even a Mark three GS1200 I had not come across those type of motors before, looking at the photos Thomas posted above the brushes are different. Sorry if my video caused this problem, I can only guess it only covers the Mk1 and Mk2 motors, I never new there were different types of motors I thought they were all the same.

Looking at the photos Thomas has posted I guess its not possible to do what I have done. It does look like the complete motor has to be removed and then dismantle. However all is not lost if Thomas can put you in the right direction as to how to replace those brushes with possible new ones, keep the broken one, anyway Thomas is certainly the right person to help so all is not lost, look forward to hear how things work out.

[Matthieu van der Sluis]

Here are some photo's of the motor, - the back with brushes, - a tiny block that I think came out of one of the brushes gate.
on the last photo you see how I demaged one of the brushes, where I asume also that tiny block came from.

[Thomas Knappstein]

This is a MK2 8V Motor.
You can´t pull off the back Plate when the Motor is still in the Projektor.
There must be dissassemled everything. Gear Box and the tiny little Gear on the Motor Shaft. Then you can pull te Rotor with the back Plate out of his Housing. But here you need new Brushes now. It is not difficult to repair this. The Brushes I´m using are from China. I have bought them from Ebay. But you have to cut them onto 6mm Length and bring a new Radius on them.

[Matthieu van der Sluis]

Dear Thomas.
Where are you located and do you take on repairs?

[Thomas Knappstein]

Hi Matthieu!
You have a PM from me.

[Melvin England]

So this morning was the one chosen when I would throw caution to the wind, follow Graham's Youtube demo on this topic, which was excellent, and see if I could solve my problem.


Not a cat in hell's chance.


Opened the drum up with a tissue underneath which was placed in such a way that should anything fall out, it would fall onto the bench as opposed to into the machinery and be never located again.

So far, so good.

I was sort of relieved to see that the inside of the barrel was a little murky, so at least I knew there would have been a problem with it (as opposed to being squeaky clean and leaving me wondering "what now ?"
I took a cleaning brush, cleaned the electronics on the barrel head and inside the barrel. Yes, it was all dirty. Turned my head away and something fell.
It was at that point I knew that one of the brushes was missing. The tissue underneath would have forced the tiny metal block to fall onto the bench.
Well, was it there? No.
Had it fallen onto the floor ? No.
Had it fallen in another direction? No.
Trust me, I dissected the whole area several times, including once by Mrs. E., including IN the projector itself but could I hell as like find the brush. No chance.
So, basically, I am up the creak without a paddle.
I managed to clean the rest of it and assemble it back together but daren't switch the projector on.

This leads me to needing your help with a few questions....

Firstly, if I did switch the unit on and try to check the take up arm, would something go bang somewhere ?

Secondly, if the answer is "no," is it possible for the take up arm to run with only one brush ?

Thirdly, does anybody have any spare brushes for this drum, or know where I can get hold of one, please ?

Until this is sorted out I cannot show either 1200' films or optical sound films and I do have one waiting to be checked.
Any help or advice would be very VERY welcome !





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