Elmo GP-E lamp not getting enough voltage to turn on?

[Shane C. Collins]

Many of the Elmo's from the 60's and early 70's have this "interlock" or switch that is tripped by the film. As the film reaches the take-up reel it pulls on a film guide that then activates the lamp. When a user pushes down on the green threader button near the first sprocket, this activates the sequence until the film reaches the take-up reel. I'm including two photos to show you were those film guides are located. The first one is from a Elmo FP-series machine, and the second photo is from a Elmo GP-E. Refer to the arrows I've drawn on each photo.
If you have the green threading button pushed down and your trying to turn on the lamp it will not light. Once the interlock/film guide it tripped the lamp will light. The Elmo FP has a lamp dial, and the GP-E has a lamp switch located at the speed control knob. Both must be on in order for the interlock to work. You can however use your finger to trip the film guide roller when the machines on. This will tell you if it's working if you don't have film handy to check the system.
I'm including a link to a YouTube video that shows how this switch/film guide activates the lamp. When the user flips down the lamp cover, watch the film guide (below bottom sprocket) move backwards, and the lamp will light, this is at :19 seconds into the video. I must also point out that the user has the lamp switch already turned on. So once the film reaches the reel the system turns the lamp on.
https://www.youtube.com/watch?v=86fXaV950O4

[James Culbertson]

Thanks Nantawat and Steve I think you are both right and after doing some checking I realized that yes, there is indeed another switch that is connected to the auto threading leaver. Now here is where I become really stupid....I looked up the manual online and after reading the whole thing I suddenly discovered that IF the auto threader is DOWN the lamp will NOT come on for any reason. (sigh) I guess I should have thought about that. My auto threader seems to be a bit stuck so I'm pretty certain thats my issue. So one wire goes from the lamp plug to the lamp switch the other wire (blue) to this switch. The metal bar on the right seems to connect to the auto threader. I'll play around with it till I get it working. Just want to say thanks to you guys for taking the time to give me some ideas and some thoughts about how I can analyze other projectors I have. I'm very glad to know that people on this site will take time out to answer questions. Thanks again

[Shane C. Collins]

The auto-threading set-up on these projectors is pretty slick, it works most of the time. I own a Elmo FPC-8 that sometimes would not activate the lamp if I was using the wrong take-up reel. The system relies on a good take-up reel that will grab the film, which then tugs the film roller to activate the lamp. Once I switched over to a good take-up the lamp activates every time now. I don't think I've ever seen a set-up like this. Which is probably why Steve was getting confused a bit. He's our electrical guru around these parts.

[Steve Klare]

Thanks Shane! I try to be at work and I certainly am at home!

All of my Elmos are later ones with sound that lack this feature.

It's always made me a little nervous that they lack some kind of interlock that turns off the lamp when the transport is stopped. Lacking this we are one broken motor belt away from a scorched print! (Murphy's Law says it will be our favorite, too!)

[Shane C. Collins]

Thanks Shane! I try to be at work and I certainly am at home!

All of my Elmos are later ones with sound that lack this feature.

It's always made me a little nervous that they lack some kind of interlock that turns off the lamp when the transport is stopped. Lacking this we are one broken motor belt away from a scorched print! (Murphy's Law says it will be our favorite, too!)

Steve, I've been following this thread since it was first posted. It wasn't until Nantawat mentioned the "interlock" when a bell went off in my head. I thought why didn't I think of that since I have the FP machine that works the same as the GP-E. One simple little switch that can throw the whole thing into a spiral hahaha.

[Nantawat Kittiwarakul]

Now I remembered that.

I once had EXACTLY this issue with my GP-E! After messing around & pulling my hair of for a good half hour why the lamp suddenly didn't light up, then realized that the projector was still in LOAD position.

A gentle tap on that autoload release roller, and the problem immediately gone. Silly me...

Once again - the most overengineered silent projector on the planet. Quite overthinking in certain regard.

[Steve Klare]

-and that's why discussion forums are great!

You don't need to reinvent the wheel: just find somebody that did a few years ago!

(-although the people that DID invent the wheel probably aren't on the internet!)