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Rattanee
Joined: 18 Jan 2015
Posts: 193
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| Posted: Mon Jan 04, 2016 6:26 pm Post subject: Lens modding (LC c-element matching) |
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Hey guys, I'm curious to know if anyone tried this before. I have a bunch of older rear projection monitors from arcade machines, and it got me thinking about converting my AC projectors to LC. I know that the lenses used in these are not directly compatible with direct projection as they are not designed to focus on those distances, however they would be a great source for coolant chambers and c-elements (color filtered!).
The big question here being whether the C-elements themselves are a 'standard', or if the actual element is different for each type of lens set? Even if so, I would like to try my luck with this. Would anyone have any suggestions on what LC lens set I could get my hands on fairly cheap to experiment with? Preferrably something that has better alternatives for replacement should this experiment succeed?
Cheers
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tschaeikaei
Joined: 08 Apr 2013
Posts: 490
Location: Germany/Saarland
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| Posted: Tue Jan 05, 2016 4:37 pm Post subject: |
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I believe these RPTV tubes beeing 5" (or in that range), but i don't know exactly.
So i think the C-elements would be too small for projector tubes of 7" and up.
I'd try to get a broken XG in your case and try those C-elements.
It could even make some sense to use a whole XG (with e.g. toasted tubes)
trying the tubes from your PG sets. Sure, they are not the same but you will know the differences better than i do.
Regards, Julian
_________________
Marquee 9500U edgeblend P43 | NEC 9PG
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Rattanee
Joined: 18 Jan 2015
Posts: 193
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| Posted: Tue Jan 05, 2016 5:00 pm Post subject: |
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I don't think they were any smaller. From what I recall, the ones in the arcade sets were Toshiba P16 tubes (though I'll check sometime during the week to make sure), which should be the same size as in the NEC PJs. I grabbed some scrapper RPTVs to replace the tubes in those a while back, and It worked like a charm. I thus now have entire coolant chamber/lens sets to spare (though as I said the lenses are not the kind that would work for direct projection).
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Tue Jan 05, 2016 6:54 pm Post subject: |
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Not even all P16 tubes are the same size! For example there is P16 equvivalent to 180DMB tubes those are apparently not the same size as P16LJE which are found in XG/G70.
C-elements have to match for the lenses as they are part of the optical system too. Julian on the other hand says the good way, you need decent LC chambers with decent lenses. The lenses found in RPTV applications are substandard, not just they are low resolution but they lack of edge focus too. Also keep in mind that RPTV chambers do not have adjustable scheimpflug.
For serious 8" LC setup a HD-18 lens is needed at least, I think the HD117-12/24 lenses are better (but they are short throw and no colored c-element is available), the top of the line is the HD-134 lens (but that is ridiculously expensive and hard to find).
_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB, VIM-DB
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cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
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| Posted: Sat Jan 16, 2016 12:29 am Post subject: |
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C elements are not standardized. They may FIT a different lens, but they will not have the same "prescription", so to speak.
Years ago I found this out when attempting to use an AmPro 9" specific C element in a Marquee LC housing. It would not focus.
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