8mm Forum: Elmo ST800 - Fuse trouble

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Posted by Daniel Florence (Member # 1920) on February 12, 2011, 09:00 AM:

Hello, I’m new on this forum ! I’ve been collecting super 8 films for 40 years, mainly cartoons and classic comedies.
I’ve got a question about Elmo ST800 projectors. I have bought two of them, they look as new but the main fuse always burns when I plug the projector. It’s just the same with a 5 A fuse instead of the original 3 A.
Does somebody know where this trouble comes from ? It seems to be quite common with ST800 since I have a third one which can work only with a 5 A fuse.

Posted by Jean-Christophe Deblock (Member # 792) on February 12, 2011, 09:06 AM:

Bienvenue Daniel!

I agree.

I have the same problem with mine.

Anybody a solution?

Posted by Steve Klare (Member # 12) on February 12, 2011, 02:30 PM:

There's something really wrong here.

I have a 3 amp fuse in my ST-800 and have never blown it in about 8 years of use. Both of you live in places where the line voltage is about double mine, so your line current should be about half, so if I never blow a fuse you should never, never blow a fuse!

The machine that blows the fuse right from the start probably has a short circuit someplace: maybe on the line to the main transformer, maybe inside the transformer itself, maybe something connected on the output side of the transformer.

The key to finding a short is being able to disconnect various circuits in the machine to see which isolated section stays short circuited. The motor section, sound and lamp circuits are controlled by switches, so these can be isolated just by turning them "off". Wherever there is a connector you can isolate just by unplugging it. Sometimes you need to be willing to unsolder a connection and restore it later.

These are times it's handy to be skilled with an Ohmmeter, or make a friend who is.

First things first though: make sure your machine is configured for the local line voltage. I'll give you odds if you plugged mine (set for 115V) into your wall socket, it would blow a fuse too!

Posted by Pasquale DAlessio (Member # 2052) on February 12, 2011, 03:14 PM:

Steve is correct. However, when working with electrical circuits always go to the source first. If you have a volt meter check the voltage at the outlet first.You want to measure the voltage to see if it's what is reccomended for the unit. Sometimes areas can have increased voltage that will blow the fuse. Then follow Steve's instructions. Good luck finding it.

Pat DAlessio

Posted by Daniel Florence (Member # 1920) on February 13, 2011, 02:14 AM:

Thank you Steve. I have an ohmmeter and I already have checked many things. I'll go on. I hoped maybe anyone knew what's wrong with some ST800...

Posted by Steve Klare (Member # 12) on February 13, 2011, 01:20 PM:

The problem you run into here is that you have an AC short, but the ohmeter is a DC device.

If you measure across the primary or secondary of the transformer with an Ohmeter, guaranteed the reading you get will seem low enough to be the problem: even if it isn't. The resistance of a transformer is just the wire in the windings: pretty low. What gives it impedance is the fact that it is inductive, and that works only with AC.

My point is to bear this in mind when you are poking around and not allow it to mislead you. I suppose it would be handy to have an inductance meter in these circumstances, but that's pretty rare as hobbyist equipment goes...

Here's a thought: The ST-800 has a funky line cord connection which I have never seen on any other device in the known Universe. When the cord gets lost it is common for people to cobble in the socket that accepts an IEC style cord (the kind you plug a computer in with, for example...). There is nothing wrong with doing this, but it doesn't mean that the people who do it have the slightest idea which wire goes where (...or why).

Do your machines have the original connector (three round pins) or a new one (three rectangular pins)?

Posted by frank arnstein (Member # 330) on February 15, 2011, 01:38 AM:

Can anyone here help me get a copy of an owners manual for the Elmo ST 800 ? Perhaps Doug knows where. I can't see a manuals link anywhere.

dogtor [Confused]

Ok Now thanks.... Found a manual here at Projector Heaven.... [Razz]

[ February 16, 2011, 12:45 AM: Message edited by: frank arnstein ]

Posted by Steve Klare (Member # 12) on February 15, 2011, 08:02 AM:

Frank,

For some reason I've never been able to figure out the ST-800 is less common than a lot of the other Elmos, so documentation like manuals and schematics is just as unusual. (There are legends of an ST-800MO for magnetic/optical playback, but I've never seen one. There's probably one in a cave somewhere, right next to the Holy Grail and the Ark of the Covenant.)

I don't think this scarcity is because of the machine itself. I really like mine. It's more basic than the ST-1200HD or the GSs, but it puts up a great picture and sound.

I think it's closest to the ST-600/ST-180 in design and shares a lot of parts.

I have the manual. When I have some quiet time in about two weeks I will scan it and offer it to the manuals section.

[ February 15, 2011, 09:19 AM: Message edited by: Steve Klare ]

Posted by Daniel Florence (Member # 1920) on February 15, 2011, 02:11 PM:

Steve, my ST800s with fuse trouble are both magnetic/optical ! (but no holy Grail, sorry...).

Posted by Steve Klare (Member # 12) on February 15, 2011, 06:00 PM:

That's interesting...

Let's get back to the port the line cord plugs into. As described above, do you think it's the original?

Posted by Daniel Florence (Member # 1920) on February 16, 2011, 11:32 AM:

I have the new connector, it's the original one.

Posted by Winbert Hutahaean (Member # 58) on February 16, 2011, 11:42 AM:

Daniel, can you post a photo of your ST-800 MO... as I never seen ones.

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