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Author Topic: Yelco P-111B and the Mystery Diode
Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003


 - posted August 14, 2015 08:37 PM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
Last year my son told me he wanted a projector of his own, so I revived a dead Yelco P-111B and gave it to him.

The machine runs fine, but the picture is beyond dim: whites are gray, it can't handle more than a TV sized screen without washing out. When he uses it at CineSea in daylight conditions he's down to an A sized sheet to be visible at all.

This uses a 50W lamp, so nobody expects it to burn holes through the screen, but it seems to me it should be a lot brighter than this. I've had other 50W machines that weren't like this.

-so I poked around...

Transformer output for the lamp: 8 Volts, fine! Lamp voltage? 3.9V! This is less than half what it should be, so the lamp power is less than a quarter what IT should be! This is under 12.5 Watts, about two editor bulbs...

I noticed something funny: the lamp circuit seems to have a diode inserted in it. Now this starts to make sense: you only let AC current flow one way, you lose the current when it doesn't flow the other.

-half the current, half the voltage, one quarter the power.

My guess is the former owner was using the machine on a small screen and cut back the brightness to stretch his lamp life. I knew the guy: he's a fellow electronics guy and doing this is definitely something he could pull off.

My question for any other owners of Yelco P-111Bs is when you look at the back of your machine near the base, do you see this hex nut on a stud passing through the chassis?

-I'm guessing: "No!".

This is something new here: we deal with machines that are worn out and damaged all the time. This may be the first sabotage!

 -

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All I ask is a wide screen and a projector to light her by...

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012


 - posted August 14, 2015 09:10 PM      Profile for Andrew Woodcock         Edit/Delete Post 
Jeez Steve, this is one Dog of a machine! get your son something decent if you wish for him to carry on the mantle.

[ August 15, 2015, 06:07 AM: Message edited by: Andrew Woodcock ]

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"C'mon Baggy..Get with the beat"

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003


 - posted August 14, 2015 09:33 PM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
Forgot our tact pills today, did we, Andrew?

What part of your answer is helpful to me here?

(If you have nothing nice to say...)

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All I ask is a wide screen and a projector to light her by...

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012


 - posted August 14, 2015 09:34 PM      Profile for Andrew Woodcock         Edit/Delete Post 
Oh dear!

In answer to your question Steve, I guess we can safely say the answer is NO.

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"C'mon Baggy..Get with the beat"

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003


 - posted August 14, 2015 09:41 PM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
To get back to my question: Does anybody here have one of these machines?

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All I ask is a wide screen and a projector to light her by...

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Mathew James
Jedi Master Film Handler

Posts: 740
From: Hamilton, Ontario, Canada
Registered: Dec 2014


 - posted August 15, 2015 09:22 AM      Profile for Mathew James   Email Mathew James   Send New Private Message       Edit/Delete Post 
Hi Steve,
I tried looking for this one to see if I could find a rotated view of the projector to see if the nut was there, but I cannot find anything....
This looks to be your machine here?
http://www.youtube.com/watch?v=YkmnzasH7X0

Other Info:
marketed in 1969-70
standard 8 mm \ super 8 mm film
format change: auto, by lever
lens: Zoom f: 1.3 \ F: 15-25 mm
lamp: 50 W, 8 V, CXR
reel capacity: 120 m
projection: forward, reverse
projection speed: variable speed
variable speed control: by rheostat
film loading: fully automatic reel to reel threading
sound: no
motor: DC magnetic motor
power source: 93-100-110-125-160-230-240 V AC, 50/60 Hz
weight: ?
dimensions: ?
made in Japan by Yamawa

Your pic may be the only uploaded back view of this one. Sorry I cannot help further.

btw- this looks like it was also marketed as another machine here:
http://www.super8data.com/database/projectors_list/projectors_ifba/ifba_quartz.htm

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--
Cheers,
Matt 📽

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Dominique De Bast
Film God

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


 - posted August 15, 2015 09:42 AM      Profile for Dominique De Bast   Email Dominique De Bast   Send New Private Message       Edit/Delete Post 
Mathew, I think that the Ifba Quartz P 111 Q is the same model as the Yelco P-111Q, which is a different projector than the Yelco P-111B.

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Dominique

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Barry Fritz
Phenomenal Film Handler

Posts: 1061
From: Burnsville, MN, USA
Registered: Dec 2009


 - posted August 15, 2015 11:35 AM      Profile for Barry Fritz   Email Barry Fritz   Send New Private Message       Edit/Delete Post 
Dominique is correct. The main difference is the 111B has the old spaceman CXR lamp which is getting quite expensive.

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Mathew James
Jedi Master Film Handler

Posts: 740
From: Hamilton, Ontario, Canada
Registered: Dec 2014


 - posted August 15, 2015 04:37 PM      Profile for Mathew James   Email Mathew James   Send New Private Message       Edit/Delete Post 
Thanx Dominique for the clarification!

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--
Cheers,
Matt 📽

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003


 - posted August 15, 2015 06:20 PM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
That is indeed the machine: it's actually a nice simple little projector with continuously variable frame rate. A lot of people like them for telecine.

In my case I just wanted something user friendly to give to my 12 year old (now newly 13) so he could have his own.

-it's kind of neat how well a kid of the "app" generation adapted to changing sprockets and aperture, framing, focusing and rewinding!

I have a little more pondering and measuring to do, but my gut is telling me once I bypass that diode things will get a lot brighter.

-next step: go through it with an ohmmeter, pencil and paper, trace the circuit and make sure my gut knows what it's talking about.

I did find him a spare spaceman lamp: worked out to about a buck an hour for the rated life! By the same token at the rate he uses it showing 200 foot silents, the two bulbs should last him until college, or Eumig or Elmo (Whichever comes first!).

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All I ask is a wide screen and a projector to light her by...

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003


 - posted September 27, 2015 09:30 PM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
I thought this story deserved an epilogue.

I traced out that circuit and found that the old friend that gave me that machine years ago did indeed do a little surgery on it. He clipped the unswitched wire from the grounded side of the lamp and soldered it to the anode of a diode he'd installed through a hole drilled in the chassis.

Why? My best guess is he was trying to stretch out the life of the lamp by cutting the operating voltage in half. It would easily get him 50 hours out of this 25 hour bulb.

Problem is that when we are at CineSea we are running pretty much at daylight conditions all day long and the biggest "screen" he could manage with the great big 12.5 Watts he had in that lamp is a card film box!

 -

-still the same. When you are 12 years old and you have a sleeve of Ritz crackers, new sneakers AND your own movie projector, life is good!

I put the wire back where Yelco meant it all along (-could see where he clipped it!). Post-surgery he showed us a reel tonight: not exactly Xenon, but much improved. This time he will smoke that screen with 50 mighty Watts!

I very much doubt we will ever hear this again: that legions of Yelcophiles will thank me for showing them their parasitic diodes, but at least the story has a happy ending!

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All I ask is a wide screen and a projector to light her by...

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Janice Glesser
Film Goddess

Posts: 3468
From: Sunnyvale, CA USA
Registered: Sep 2011


 - posted September 28, 2015 12:08 AM      Profile for Janice Glesser     Send New Private Message       Edit/Delete Post 
Steve ... your son is adorable and he looks so content next to that little projector. This is a great story. Your son will always remember that projector as a bond he had with you. Good job Dad!

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

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Graham Ritchie
Film God

Posts: 4001
From: New Zealand
Registered: Feb 2006


 - posted September 28, 2015 12:25 AM      Profile for Graham Ritchie   Email Graham Ritchie   Send New Private Message       Edit/Delete Post 
Steve

You might find this of interest.
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Dominique De Bast
Film God

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


 - posted September 28, 2015 01:36 AM      Profile for Dominique De Bast   Email Dominique De Bast   Send New Private Message       Edit/Delete Post 
Well done, Steve !

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Dominique

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003


 - posted September 28, 2015 08:57 AM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
Thanks Guys and Gal!

That's really interesting Graham. So it was a do it yourself Hi-Lo switch, but all we got was "Lo"! I wish he'd done the switch as well: I would gladly have left it alone.

I think this is actually good for Steven. Everything he deals with is software: Apps, Games, Uploads! This essential knowledge these days, but I think it's good to understand motors, gears, belts and pulleys too! Someday when there's steam pouring out of his radiator cap, a little mechanical horse-sense will serve him well!

(I'm grateful for it every time the garage door or the dishwasher goes into rebellion!)

This also says a lot for the people at CineSea. He walks around the place like one of the Veterans and the guys make a point of putting interesting stuff on screen for him. Besides, that picture only ever happened because Doug was willing to clear a spot on his table for him.

I'd love to know what he was watching here. I'm betting the title isn't "Homework"!

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All I ask is a wide screen and a projector to light her by...

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Martin Jones
Phenomenal Film Handler

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


 - posted September 28, 2015 10:40 AM      Profile for Martin Jones     Send New Private Message       Edit/Delete Post 
Do projectors have radiator caps?

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

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003


 - posted September 28, 2015 10:47 AM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
General knowledge is generally applicable!

There's certainly a lot going on here in terms of power, cooling, temperature and even over-temperature that you can't understand the green fog condensing on your windshield until you pretty firmly grasp.

Not to worry: There's a lot of intermediate steps between the projector and a car, but he has to start somewhere.

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All I ask is a wide screen and a projector to light her by...

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Graham Ritchie
Film God

Posts: 4001
From: New Zealand
Registered: Feb 2006


 - posted September 29, 2015 12:12 AM      Profile for Graham Ritchie   Email Graham Ritchie   Send New Private Message       Edit/Delete Post 
I think its very important for young people to grasp how things work as much as possible and if they can "visualize" the big picture, then if they have a problem, hopefully that in turn will give them a better understanding how they might be able to fix it. [Smile]

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003


 - posted September 29, 2015 08:21 AM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
There's a certain feel for how things work that you actually get from working those things.

-as good as simulations may be they will never develop these instincts in people.

It's like when you are driving your car: you start to sense something isn't right even before you can describe why. As soon as you can you start checking things out and maybe catch the problem while it's still a small one.

Without this you will drive until a major piece falls off or something bursts into flames!

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All I ask is a wide screen and a projector to light her by...

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