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benareeno
Joined: 22 Mar 2006
Posts: 1614
Location: ottawa, canada
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| Posted: Fri Feb 01, 2013 6:31 am Post subject: questions about this seriously underrated projector (708) |
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I think this 708 with p16 tubes is the most underrated projector out there...I am watching this ES focus setup, and I am not the least bit concerned with a lack of sharpness. Color filtered lenses bring this projector quite easily on par with something like a NEC PG (and likely superior). And the small Barco chassis is a real +...but I have a couple of questions..
1. the p16 tubes in a 708, are they found in other projectors? THat is to say, could I swap one in from some other Barco chassis or is this not possible?
2, Would a 708 with toshiba tubes be totally incompatible with this one in terms of other boards?
3. If the major flaw with these Barco's is arcing..is there anything that can be done which might prevent an arc? Any type of shielding or preventative measure that can be taken?
I can't believe I bought this projector for 45 dollars...clean tubes and color filtered lenses. It is decidedly not LC, but I am not feeling like I am missing that all that much. I am genuinely pleased with the pic. I have owned 2 of these in the past and they weren't even close to the pic I get out of this one..it just goes to show that you can't really blanket a projector model as better than a different model. This is a better pic than some NEC's I've had.
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Fri Feb 01, 2013 2:03 pm Post subject: |
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Also found in a DWIN 700 with different HV lead ends.
According to VDC, the 180 Toshiba tubes will swap with the P16 tubes, but won't last long, as something in the CRT drive design wears out the cathodes quickly. I never tried it, but I think that might have been a bluff to sell the more expensive P16 tubes. Don't know for sure though.
Shield the crap out of the HV leads to prevent arcing. That's about all you can do.
It is a nice little set when it's not smoking convergence boards. Of all the sets I sell, it's definitely the most problematic. The best one was last week, when a deflection board caused no convergence controls to work. There's a H pulse type signal that sends signals to the convergence board for generating waveforms. It was missing. Turns out that underneath a big electrolytic cap. the PC board trace had shorted to ground. Never found the exact place of the short, but I had to cut a PC board trace and jumper over the cap area. Go figure.
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Hulio
Joined: 15 Apr 2006
Posts: 494
Location: Belgium
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| Posted: Fri Feb 01, 2013 2:08 pm Post subject: |
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Congrats, good score for 45$. Despite the fact that they are rated as 7'' machines, those tubes are 8''. In combination with color filtered HD145 lenses, they are good for 1080i / 720P if it's a data version. Now, to answer your questions:
1. Barco Cine 7 and some Seleco's used the same tubes.
2. The tubes are the same ( Toshiba = P16LNG22 ), most of the board are compatible depending of version ( data, vision, vision MM ). Look at the R762xxx nr. to be sure.
3. Yes, it is. The best thing to do is shielding the deflection yoke of the blue tube. This is in close proximity with the HV splitter and that's no so healthy. On Cine 7 ( in fact a later BD708 ), Barco did it with a metal cage and for good reasons, i think. Look at the pics.
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CasetheCorvetteman
Joined: 09 Nov 2008
Posts: 6326
Location: Australia
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| Posted: Sat Feb 02, 2013 2:24 am Post subject: Re: questions about this seriously underrated projector (708 |
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| benareeno wrote: | | Color filtered lenses bring this projector quite easily on par with something like a NEC PG (and likely superior) |
Bold statement 
Tubes wont last as long though, and being ES focus itll only soften up as the hours roll on. I wonder how close those tubes are to the P16s in rear projection sets?
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benareeno
Joined: 22 Mar 2006
Posts: 1614
Location: ottawa, canada
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| Posted: Sat Feb 02, 2013 4:24 am Post subject: |
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they're certainly a lot bigger than any rear projection set that I've seen...
considering I might put 150 hours on it in a year, I think I'll be ok.
how do I shield these items? I notice a large yellow plastic sheet came with the projector, and I'm not certain where it goes...maybe it's some form of shielding, I'll have to see where it might fit.
How do I further shield the hv leads?
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benareeno
Joined: 22 Mar 2006
Posts: 1614
Location: ottawa, canada
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| Posted: Sat Feb 02, 2013 4:36 am Post subject: |
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I might as well ask...what causes an arc? Did my other projectors arc and it just wasn't an issue? Or, is the Barco actually prone to arcing?
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CasetheCorvetteman
Joined: 09 Nov 2008
Posts: 6326
Location: Australia
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| Posted: Sat Feb 02, 2013 8:40 am Post subject: |
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Yeah, i wonder if the rear pro tubes will work though?
Ive got 2 rear projection sets here with P16s in them, the Panasonic Tau GIGA has longer tubes then the LG.
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Hulio
Joined: 15 Apr 2006
Posts: 494
Location: Belgium
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| Posted: Sat Feb 02, 2013 12:52 pm Post subject: |
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| benareeno wrote: | | I notice a large yellow plastic sheet came with the projector, and I'm not certain where it goes...maybe it's some form of shielding. |
Yes, that shielding sheet comes on top of the SMPS/HV section. If you open the tray you'll be able to see the fixation bolts.
P16 tubes from RP machines won't fit. Most of those machines use LC tubes. It means that the glycol is also used to cool the phosphor. AC tubes are cooled by a thin chamber ( cooling fluid between phosphor and a glass front plate ).
So if you strip a LC tube and use it as AC, it will implode before you'll be able to watch 20 min. of video, due to lack of cooling.
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CasetheCorvetteman
Joined: 09 Nov 2008
Posts: 6326
Location: Australia
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| Posted: Sat Feb 02, 2013 11:44 pm Post subject: |
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Says who? If you remove an LC housing and replace it with an AC housing there is no reason it would implode.
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Sun Feb 03, 2013 12:53 am Post subject: |
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I think he's just saying that a non liquid cooled tube will implode. That's not quite true. Long ago, VDC sent me an XG tube that they forgot to fill, and I didn't catch it. Was wondering for 45 minutes why there were green halos around everything. I pulled the tube, and saw that the fill screws were missing. THe tube didn't implode, but I did get phosphor burn within the 45 minutes that I was playing around with the set and tube. They replaced it under warranty.
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CasetheCorvetteman
Joined: 09 Nov 2008
Posts: 6326
Location: Australia
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| Posted: Sun Feb 03, 2013 6:10 am Post subject: |
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Yes he may well be, but AC or LC, itll still be cooled, provided you put the glycol in there 
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Sun Feb 03, 2013 9:23 am Post subject: |
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Hulio is partly right. Indeed there are special LC tubes, those have plain glass faceplate like other projection tubes, but the inner side of the face glass is curved where the phosphor is. Those tubes are imposible to use in AC environment I think.
_________________
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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CasetheCorvetteman
Joined: 09 Nov 2008
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Location: Australia
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| Posted: Sun Feb 03, 2013 10:42 am Post subject: |
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Why? They have the same outer dimensions, and why not use them as LC anyway?
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Decibel
Joined: 31 May 2007
Posts: 904
Location: Roma - Italia
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| Posted: Sun Feb 03, 2013 11:58 am Post subject: |
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| benareeno wrote: | | I notice a large yellow plastic sheet came with the projector, and I'm not certain where it goes...maybe it's some form of shielding, I'll have to see where it might fit. |
I think that it fit as picture below.
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Domenico (Barco fan!)
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Hulio
Joined: 15 Apr 2006
Posts: 494
Location: Belgium
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| Posted: Sun Feb 03, 2013 1:16 pm Post subject: |
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| CasetheCorvetteman wrote: | | Why? They have the same outer dimensions, and why not use them as LC anyway? |
I think i am misunderstood here, i'll try to explain better.
It's not about the physical dimensions of the tubes here, nor the inner curvature of the phosphor. It has to do with the very different ways of cooling.
Also, LC ( liquid coupling ) should not be confused with liquid cooling.
Because the excited phosphor becames hot from the electrons bombardment, the faceplate of the tube has to be cooled.
Tubes designed for air coupled projectors have a double glass faceplate which is filled with cooling glycol, like in first pic.
The ones designed for liquid coupling machines does not have that because they are anyway cooled by the liquid coupling
glycol ( trapped between the crt and the C element ), like in second pic.
Most of the retro projectors are equipped with liquid coupled tubes and short trow lenses. You can't swap the entire tube with the liquid coupling chamber because it won't fit in a air coupled machine and even than, your long trow front projection lenses becames useless.
You can however strip the tube from the liquid chamber ( third pic. ) and put it in a air cupeled projector but you'll end up with tubes without cooling, and that's no so clever. Even if they won't implode or crack, after watching a movie they will be cooked brown, like Curt said.
So the TS can not put the P16's tubes from a retro projector in his 708.
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Last edited by Hulio on Sun Feb 03, 2013 1:21 pm; edited 1 time in total
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Sun Feb 03, 2013 1:20 pm Post subject: |
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Wait a minute... It is not impossible to remove a tube from the LC chamber then install it in an AC chamber and vice versa.
_________________
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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Hulio
Joined: 15 Apr 2006
Posts: 494
Location: Belgium
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| Posted: Sun Feb 03, 2013 1:39 pm Post subject: |
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Off course, not impossible but not recommended. Read my post above.
Putting a AC tube in a LC chamber is also a bad idea. You are adding a extra refraction in the optical path and destroy
the advantage of having LC ( the double front glass ).
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Sun Feb 03, 2013 1:44 pm Post subject: |
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Did you know that Electrohome used the same bare tubes in their 8500 and 8500 LC only in different chambers. Not to mention the NEC XG AC and LC models...
The AC tubes didn't born with the dual faceplate on them, that is an individual assembly unique to every projector maker brand. I think when we (me for sure) talk about tube swaps we talk about bare glass tubes without any assembly on them.
_________________
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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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Sun Feb 03, 2013 3:11 pm Post subject: |
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| Hulio wrote: | Off course, not impossible but not recommended. Read my post above.
Putting a AC tube in a LC chamber is also a bad idea. You are adding a extra refraction in the optical path and destroy
the advantage of having LC ( the double front glass ). |
The raw tube, glass only, is identical between AC and LC. As gjaky says below, putting an AC tube into an LC chamber on an 8500 is pretty easy, you just need some patience. It's impossible to fit the whole AC tube, housing and all, into an LC chamber.
It's much harder to take an NEC XG or PG tube out of either chamber.
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Decibel
Joined: 31 May 2007
Posts: 904
Location: Roma - Italia
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| Posted: Sun Feb 03, 2013 4:35 pm Post subject: |
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If you want put raw tubes into used LC chambers....
ATTENTION!!!
There are four spacers to set the correct distance from tube's surface to the c-element.
http://www.curtpalme.com/forum/viewtopic.php?p=306897#306897
_________________
Domenico (Barco fan!)
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