8mm Forum: Converting a GS Light Output?

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Posted by Tony Milman (Member # 7) on April 27, 2005, 11:20 AM:

The death of Mr Clancy's Xenon like GS recently set me thinking as to whether it would be possible to adapt the bulb in a DVD projector for use in a GS or something similar.

If it was physically too big to insert could the light be taken from outside the projector and run down a white tube to the gate for example

Anyone have any ideas?

Posted by John Whittle (Member # 22) on April 27, 2005, 12:25 PM:

There are certainly a number of lamps that might be used but remeber that you when measure light output from a film projector you have to consider the shutter which takes out 50% of the light! Hence a video projector lamp might not "improve" the situation much. Also light is measured logrithmically, a 100 percent increase in light is ONE f/stop.

The other problem is getting the light through the aperture and that would be the challenge. Lamps are made to cover a specific area and you'd need to come up with suitable optics which could withstand high heat to concentrate the light to the 8mm aperture size.

None of this is hard but could be expensive when dealing with one-off or twos or threes. A xenon lamp or a Marc 300 (if you can still get them) is probably a closer fit. Many 16mm projectors were available at one time with Marc 300 lamps and Eiki even made a model where you could switch out the lamps with a regular EJL to use the projector in a classroom or auditorium.

One of those might be a good starting point.

John

Posted by Ugo Grassi (Member # 139) on April 27, 2005, 01:44 PM:

What's happened to the Clancy's Xenon GS?
About the lamp: it's impossible to use the lamp for the DVD projector, bacuse the colore temperature is wrong for the film. A modern discharge lamp for home real cinema is the HTI serie.

Posted by Kevin Faulkner (Member # 6) on April 27, 2005, 05:21 PM:

Hi Ugo,
I did email you about his power supply. It looks like the power supply might be beyond economical repair [Frown]

Kev.

Posted by John Clancy (Member # 49) on April 28, 2005, 02:36 AM:

Sob sob. And just as Master and Commander is on its way.

Pass the hemlock.

Posted by Ugo Grassi (Member # 139) on April 28, 2005, 09:59 AM:

Hi Kevin,
right now I remember!

Hi John,
did you consider to change the original power supply with an other one by Mitronic, for the 250 w. HTI lamp?

Posted by Bill Parsons (Member # 244) on April 28, 2005, 02:43 PM:

Ugo
I have Johns GS and power supply with me for repair, it is indeed beyond economical repair, not a very well made unit, plus full of obsolete parts, you may remember you were kind enough to send me the details of your HTI mod, I have considered trying a Mitronic power supply, but the Gemini lamp is a 35v lamp and I am not certain of the trigger volts, or how well it would perform with the Gemini lamp, I have emailed Mitronic twice but they do not reply to my emails, have seen two of the correct power units on ebay, but they would only ship to the USA [Mad]

I have spent more time on this power unit of Johns than any other job in 38 years of repairs, have even considered hanging myself [Frown]

Bill.

Posted by John Clancy (Member # 49) on April 28, 2005, 03:20 PM:

Don't hang yourself Bill...

Well, not until my projector's back in working order anyway.

Posted by Kevin Faulkner (Member # 6) on April 28, 2005, 04:40 PM:

Hi Bill, Is it semiconductors that you cant source? Let me know what your after and I'll try to help where I can. I have recently been building up a stock of many of the obsolete semis used in the GS. I have even been able to source that UPC1042 and 1002 as used in the GS xenon power supply and speed control board.
There are way and means [Wink]

But dont hang yoursef. JC will just have to make do with a candle. [Big Grin]

Kev.

Posted by John Clancy (Member # 49) on April 29, 2005, 04:53 AM:

Bill, if I don't get hold of you take a look at what Tony has found... http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=1477&item=6390168498&rd=1&ssPageName=WDVW

Does that look like I could use the power supply to run the GS lamp as well as the Eiki, or what?

Posted by Bill Parsons (Member # 244) on April 29, 2005, 12:49 PM:

John/Kevin
John, yes you could use the eBay Elf power unit for both machines providing the ignitor is within the separate power unit (they often are in the early designed units) and if the power unit has its own mains transformer.

Kevin, the problems with Johns power unit are many, the oscillator transformer is o/c, it has various unmarked! transistors that are s/c, I have no diagram, and conditions have to be just right on this type of power supply
or the very expensive power transistors short out, it is just not a proposition.

Regards, Bill.

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