Running ELMO Projectors bought directly from Japan in the USA - How?

[Joe Balitzki]

There are always numerous ELMO Super 8 Projectors listed on eBay that are from Japan sellers. I know that ELMO Projectors sold overseas have a voltage selector that can be changed. ELMO Projectors sold in the USA do not have that feature. Many state that they are 50/60 Hz. Since they have a "Frequency Generator Servo DC Magnet Motor", when for example the voltage selector is set to 115 V AC will the projector run at the correct speed at 18 or 24 fps? If not, how does one run a projector from Japan here in the USA without causing damage to it? 🤔 Paging Steve Klare! 🙂

[Steve Klare]

Good Morning Joe,

At least most of the time, I'd expect there to be a choice of different taps on the main transformer.

115V is not so much higher than 100V that a lot of internal circuitry couldn't be happy on either, the problem is the brightness and lifetime of the lamp would change a lot since the lamp power would vary with the square of the voltage. (115V would produce about 32% increase in power over 100V)
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ST1200-HD Main Schematic from Film-Tech Warehouse


-for example here is the power input section from the ST-1200HD. If you look between the fuse and the transformer primary winding (roughly dead center on the picture) , there is a selection between 110Vac, 105Vac and 100Vac. You would change this around to select more or less primary turns so the voltages on the secondary are correct. Since "100V" is selected in the schematic, this machine would be configured for Japan.

[Joe Balitzki]

Steve,

If I understand correctly, ELMO made allowances for changing the voltage that when done the projector would work as it is supposed to. But at the expense of shorter lamp life. Is that correct? Now if for example the above schematic was changed to 110Vac, would the lamp life be equivalent to a ST-1200HD projector that was sold in the USA that does not allow for voltage selection?

[Steve Klare]

In that schematic, the change of voltage tap would restore the voltages inside the machine to exactly what they are supposed to be given the change to the correct tap.

There is a second pair of taps down below marked "(H) 15V" and "(L) 13V". These are the two voltages for the EFP lamp for high and low brightness. Choosing the correct 110V, 105V or 100V input voltage tap will keep these at the desired 15V and 13V.

A transformer is kind of like a set of gears: depending on a ratio between the input and the output, either speed (gears) or volts (transformer) can get multiplied or divided. A transformer has windings that establish a magnetic field in a core. If you apply 100 Volts to 100 turns you have 1Volt/turn. If you stick a second winding in the field with 5 turns, you get 5 volts. If you introduce a third winding with 150 Turns, now you get 150 Volts. If you stacked the 5V on top of the 150, you could have 155V. (This is very useful!)

When you use the 100V tap, those extra windings between the 100V and 110V taps are just flapping in the breeze and not doing anything (-but if you measured the voltage on that 110V tap, you would still see 110Vac!). It works the other way too: applying 110Vac to the 110V tap would still produce 100Vac on the disconnected 100V tap.

So choosing the high voltage or lower voltage taps is just trying to match the number of turns to the number of volts so the volts per turn wind up exactly where you need it.

[Steve Klare]

By the way: A lot of the time you see a piece of equipment that is sold at a fixed voltage rating, it actually still has the capability for other voltages, but simply doesn't admit to it.

There are various safety agencies around the world that establish the criteria for some piece of equipment to be safely operated in that country. A lot of these standards involve preventing a building fire in the event something goes wrong with the device. This is the reason that many things have a fuse, so if it shorts out, the fuse will pop instead of something either inside or outside the case bursting into flames and maybe taking down a neighborhood (A hundred and more years ago, this happened a lot!). Others involve protecting people using these devices from getting electric shocks. This is why the third prong on the line cord became so common, so if something live shorted to a grounded metal case it would blow the fuse instead of maybe killing the next person to grab the carrying handle.

If you look on a projector sold in the USA, it will have an Underwriters Laboratory plate on the case. Often it will rate the machine at 115Vac, even though there may be taps for other voltages inside.

They could get UL certification at the other voltages the machine is capable of, but each configuration would need to be tested, and there would be more paperwork and higher costs.

It's simpler and cheaper just to get "115V only" certification and call it a day. I don't think that these manufacturers wanted the average user monkeying around with the voltage settings anyway: that's just asking for trouble! Even if they don't pour 230VAC into a machine rigged for 115V, sooner or later someone will try changing taps while still plugged in!