8mm Forum: Elmo st1200 low light output???

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Posted by Mark L Barton (Member # 1512) on April 02, 2012, 09:14 AM:

Hello all. I have just acquired an old ST1200 (OPT/MAG) projector that has stood in a garage for 20 years. Quite a musty old machine, but a clean up and she is running just fine with great sound from both mag and opt. A new lamp was fitted but....the light output is awful, probably about 30% of what it should be. Have cleaned the lens, checked the all guides etc, even removed the frosted diffuser, but still very low light output. I bought a new lamp from Ebay, an EFR 15v 150w, is this the wrong lamp??? Advice please, and thank you in advance for any help received. Cheers

Posted by Steve Klare (Member # 12) on April 02, 2012, 10:34 AM:

Hi Mark,

That is the correct lamp.

My best guess is is oxidation or low contact pressure (or both) on the lamp socket. Maybe sliding the socket on the pins a couple of times will be enough to break through. If it is pressure you can replace the socket.

If you have the low, high lamp brightness switch maybe you should work that back and forth a few times and see what happens. Those contacts could be oxidized too. (This is my other best guess...)

If you were living in my part of the world I'd wonder if your voltage setting was for some other input voltage, but since your mains voltage is already up on the high end of the worldwide range (and the rest of the machine works...) I don't think that's it. If you were popping lamps, fuses and semiconductors, well maybe.

Can you measure the lamp voltage?

Posted by Jon Addams (Member # 816) on April 02, 2012, 10:48 AM:

It could also be a defective lamp, I've had similar problems before where a different lamp (the same type of course,) fixed the problem.

If it doesn't, then you will have a back up lamp [Big Grin]

Jon

Posted by Steve Klare (Member # 12) on April 02, 2012, 12:18 PM:

Hi Jon,

We've seen repeat bad bulbs here once or twice.

Murphy said:

"If it can go wrong, eventually it will go wrong."

My money is still on something goofy with the machine!

Posted by Jon Addams (Member # 816) on April 02, 2012, 02:16 PM:

quote:
"My money is still on something goofy with the machine!"

Hey Steve,

You're not getting my $$$ on that one, you are the pro and you are probably right but it's always good to have an extra lamp.

See you at CineSea next month?

Jon

Posted by Steve Klare (Member # 12) on April 02, 2012, 03:12 PM:

If I'm a pro at anything it's not projector repair.

Call me an unliscensed physician who's saved more than he's killed...at least so far!

My kid won the science fair at his school and the county-wide science fair is the same weekend as Cinesea at the Lab where I work. So I'm trying to work out how I can do both, but If anything I need to err on the side of not disappointing my son!

Posted by Tom Photiou (Member # 130) on April 02, 2012, 04:29 PM:

Hope i dont sound too daft here but is the film heat protector moving upward when you switch to forward projection, it normally comes down whn you freeze frame to prevent the film burning, ive had this in the past myself.

Posted by Mark L Barton (Member # 1512) on April 03, 2012, 03:49 AM:

Thank you guys for the replies, hmmm yes have checked off all those procedures, and Tom, double checked that the still frame diffuser was moving out of the way, it is. Have found the service manual and it states a certain voltage should be found on the output of the ceramic lamp holder, so I will check that asap. Many thanks to you all. Cheers

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