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Topic: Eumig 824

Terry Sills
Phenomenal Film Handler

Posts: 1423
From: Weymouth,Dorset,England
Registered: Oct 2012

posted August 22, 2014 09:37 AM

I have 2 Eumig 824's but one is running slow. After taking the rear cover off both of them I noticed that the one running slow was set at 60HZ. The other was set at 50hz. Is this the reason that it is running slow and what is a HZ anyway? My knowledge of electrics is not good

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Martin Jones
Phenomenal Film Handler

Posts: 1269
From: Thetford , Norfolk,England
Registered: May 2008

posted August 22, 2014 10:28 AM

hZ is a measure of the mains frequency. These Eumig machines run at a speed dependant on the mains frequency: they will run 20% faster on 60 hZ mains than on 50hZ.
BUT, the position of the flag will not change the speed at which they run on any particular frequency...... only the upper and lower limits of speed range available from the front panel speed control.

Proceed as follows... set both flags to 50 hZ. BOTH machines should then be capable of running at at least 24 fps with the speed controls at the top setting, and get down to at least 18 fps at the bottom setting. If they do, all is well. If not, some attention is needed.

Let us know \what you find.
Martin

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Retired TV Service Engineer
Ongoing interest in Telecine....

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Maurice Leakey
Film God

Posts: 5895
From: Bristol. United Kingdom
Registered: Oct 2007

posted August 22, 2014 10:39 AM

In our young days we always knew that British mains electricity was 50 cycles per second, but after the International System of Units in 1960 the expression "cycles per second" was replaced by Hertz (Hz).

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Maurice

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Terry Sills
Phenomenal Film Handler

Posts: 1423
From: Weymouth,Dorset,England
Registered: Oct 2012

posted August 22, 2014 11:52 AM

Martin
I don't understand. If you are saying that it will run 20% faster on 60HZ why will changing the flag switch not change the speed. Excuse my ignorance on these matters.

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Martin Jones
Phenomenal Film Handler

Posts: 1269
From: Thetford , Norfolk,England
Registered: May 2008

posted August 22, 2014 01:04 PM

It runs 20% faster IF YOU PUT IT ON A 60hZ SUPPLY. Moving the flag doesn't put it on a 60hZ supply; your mains supply IS STILL 50 hZ.
Moving the flag to 60 hZ simply moves the limits of the MECHANICAL speed adjuster downwards to achieve. the same RANGE of speeds.

The Eumig range of projectors use a Constant speed motor (speed fixed by mains frequency) with a variable ratio mechanical drive.
The motor runs at 3000 rpm on 50 hZ mains; 3600 rpm on 60 hZ mains.Therefore, the range of speed ratio required for 18 to 24 fps on 50 hZ is from 3000/18 to 3000/24. Putting the flag in the 50 hZ position sets the mechanical adjustment to those ratio limits.
The range of speed ratio required on 60 hZ mains is 3600/18 to 3600/24. Putting the flag in the 60 hZ position sets the mechanical adjustment to the different. ratio limits.

The flag position therefore has an effect on the speed you can achieve: a flag position of "60 hZ" when the projector is on 50 hZ mains results in slower speeds. A "50 hZ" flag setting when the machine is on 60hZ mains will result in faster speeds

Can anyone else put it clearer?

Martin

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Retired TV Service Engineer
Ongoing interest in Telecine....

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Dominique De Bast
Film God

Posts: 4486
From: Brussels, Belgium
Registered: Jun 2013

posted August 22, 2014 01:09 PM

I always thought that 60 was for the US electricity net system and 50 for the European one and that it could seriousely dammage a projector to use it wrongly set (60 in Europe and 50 in the US).

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Dominique

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Paul Mason
Jedi Master Film Handler

Posts: 540
From: Aldershot, Hampshire, UK
Registered: Nov 2013

posted August 22, 2014 02:57 PM

The mains supplies are indeed 50Hz in Europe and 60Hz in North America but projector manufacturers used the same motors for both so the projectors were compatible with both. The correct speeds are obtained mechanically by selecting the right drive ratio. This does not apply to projectors with AC/DC universal motors or low voltage DC motors.

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Paul.

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Martin Jones
Phenomenal Film Handler

Posts: 1269
From: Thetford , Norfolk,England
Registered: May 2008

posted August 22, 2014 03:08 PM

Certainly no damage with the Eumigs, Dominique,they are happy with either. There are also 50/60 hZ voltage tappings on the transformer of some machineswhich make fine allowance for transformer losses between systems, but the effect of wrong connection is not serious.

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Retired TV Service Engineer
Ongoing interest in Telecine....

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Terry Sills
Phenomenal Film Handler

Posts: 1423
From: Weymouth,Dorset,England
Registered: Oct 2012

posted August 23, 2014 05:55 AM

Martin
Ok I understand about the frequency now and from you say in the last paragraph it would seem that the projector runs slower if the flag is on 60HZ. I have switched the flag to 50, which is what it should be set at, and it seems to be running fine now at the proper speed. Thanks for your help.
Terry

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