I was warned about VDC rebuilds but I have to learn the hard way. - Page 6 - AVS Forum | Home Theater Discussions And Reviews
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post #151 of 177 Old 07-03-2005, 11:49 PM
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I think that is just what they are doing with the all new glass tubes. Buy already phosphored frontglass and seal it to the rest of the tube.
If they only would fire up the tube during the evacuation as Reinhard suggested to remove more impurities. And it seems it DOES matter how long and how good you evacuate them.
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post #152 of 177 Old 07-04-2005, 08:38 AM
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Yes, it does matter, because gasses diffuse into the glass and it takes time to draw them
out via a very hard vacuum. That's the reason why tubes include getters, to absorb
and passivate gasses that diffuse out of the glass envelope, and to a lesser extent,
out of the tube structures as well. The getter is seen on vacuum tubes as a shiny,
mirrored spot (or several) somewhere on the side of the tube glass. It is actually a
patch of deposited metals including Beryllium, which will react chemically with virtually any
type of gas that they come into contact with. CRTs have getters, too, but they're not
visible most of the time as they're deposited inside the aquadag layer, usually.

The getter material is provided inside the getter cup, which is usually a ring-like structure
that is part of an electron gun assembly. It's fired after tube evacuation by means of
subjecting it to a strong radiated radio frequency current. The getter material blows out
of the cup and deposits on the side of the tube.


So is VDC offering new glass rebuilds on 8" tubes at this time? Or only 9"?
And which models of 9"?





CJ
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post #153 of 177 Old 07-04-2005, 09:26 AM
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Quote:
Originally Posted by techman707
I don't see it as being a problem and don't really understand what the big deal is since it's been the rule all along. If you want to sell something you can use the new for sale section or even Videogon. If you need more than that, you must be selling something that nobody wants. ;)
Well put by a seller that's always followed the rules.

Everyone likes Terry, Curt and many of the other resellers on the forum, so most of us don't mind their sig files and occasional self promotion. But I can see AVS' point. There are plenty of other more appropriate places to ply your wares. It's not like if you're not allowed to sell here, your merchandise can not be sold. Same goes for buying. I've managed to buy 5 or 6 CRT PJs, and none of them were even remotely the result of AVS.

I really don't see many complaints...well, actually, there's a LOT of complaints. But they're all from the same hand full of people that have stuff for sale. Maybe those that are offended could start another forum like secstate mentioned. Good luck! There's already plenty of existing HT forums that are virtually dead. AVS is the king, and will continue to be the king, regardless if a hand full of people leave in a huff over a rule that should have followed all along.

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post #154 of 177 Old 07-04-2005, 10:04 AM
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The altitude of the plant along with quality of the equipment regulates the degree of evacuation. I think 29.9 in. is the best they could hope for. As far as impurities are concerned, only gasious impurities can be removed, solids can not. That's why a clean room is required for production. I've heard it suggested that low emission tubes with otherwise good phosphors could be re-gunned only. I doubt they would attempt to do even try that.

Chip

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post #155 of 177 Old 07-04-2005, 10:10 AM
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My only hope is VDC gets its act together before the digitals get to where these discussions become a mute point

Fernando
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post #156 of 177 Old 07-04-2005, 11:31 AM
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No tube would even RUN if the vacuum in it were equal to a 29.9 inch reduction vs. standard atmospheric pressure.


Vacuum pumps used in the air conditioning industry achieve harder vacuums than that.
They can, under ideal circumstances, achieve vacuum levels of a few millitorrs.

(Torr: 760 Torr equals standard atmospheric pressure of 14.7 PSI.)


10e-4 to 10e-6 Torr (1/10,000th to 1/1,000,000th of a Torr)

The beginning of serious vacuum, at least for the amateur. "Traditional" applications include low current dc particle accelerators (e.g. Van de Graaff), hot cathode x-ray tubes, electron microscopes, electronic tubes and other small particle accelerators (betatron, cyclotron, linac). Lower decade pressure range for vacuum spark devices (electron beam/x-ray) including MeV range pulsed accelerators.



CJ
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post #157 of 177 Old 07-04-2005, 12:33 PM
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I need to clarify that my reference to the Blue/White and Blue/Blue on the guns is for the P19 tube and I was only going by the info Charlie told me.

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post #158 of 177 Old 07-04-2005, 01:06 PM
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Quote:
Originally Posted by cmjohnson
No tube would even RUN if the vacuum in it were equal to a 29.9 inch reduction vs. standard atmospheric pressure.


Vacuum pumps used in the air conditioning industry achieve harder vacuums than that.
They can, under ideal circumstances, achieve vacuum levels of a few millitorrs.

(Torr: 760 Torr equals standard atmospheric pressure of 14.7 PSI.)


10e-4 to 10e-6 Torr (1/10,000th to 1/1,000,000th of a Torr)

The beginning of serious vacuum, at least for the amateur. "Traditional" applications include low current dc particle accelerators (e.g. Van de Graaff), hot cathode x-ray tubes, electron microscopes, electronic tubes and other small particle accelerators (betatron, cyclotron, linac). Lower decade pressure range for vacuum spark devices (electron beam/x-ray) including MeV range pulsed accelerators.



CJ
So what degree of vacuum exists within a normal crt?

Chip

Current owner of the last/best AmPro on the planet. The mighty 4600HD, and it's still running...better than Barco's, especially southern ones.
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post #159 of 177 Old 07-04-2005, 02:27 PM
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10e-4 to 10e-6 Torr (1/10,000th to 1/1,000,000th of a Torr)

The beginning of serious vacuum, at least for the amateur. "Traditional" applications include low current dc particle accelerators (e.g. Van de Graaff), hot cathode x-ray tubes, electron microscopes,

ELECTRONIC TUBES

and other small particle accelerators (betatron, cyclotron, linac). Lower decade pressure range for vacuum spark devices (electron beam/x-ray) including MeV range pulsed accelerator



CJ
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post #160 of 177 Old 07-04-2005, 04:07 PM
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Ok, now your just getting wacky. Pressure is measured in Pascals. A Tor is a pile of rocks.

Little pressures = Pascals

Normal atmospheric pressures = Kilopascals

High pressures (like stresses in materials) = Megapascals and Gigapascals.

But it's all Pascals.

I guess you can use mm of mercury - that's metric too, but Torr? C'mon you just made that up. (There's a joke here).

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post #161 of 177 Old 07-04-2005, 06:13 PM
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Just to add some certainty and confusion to the "colour code" debate:

http://www.trainedassassins.net/Chris/P16LJE.JPG
http://www.trainedassassins.net/Chris/TUBE NUMBERS.JPG

08 = Yellow and White
07 = Blue and White

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post #162 of 177 Old 07-04-2005, 10:26 PM
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So the XG should be sharper than the PGx?
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post #163 of 177 Old 07-04-2005, 10:38 PM
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Quote:
Originally Posted by RoBro
So the XG should be sharper than the PGx?
Roland
They're the same tubes, so whether one would be sharper than the other would be yoke & coil dependant.

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post #164 of 177 Old 07-04-2005, 10:46 PM
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Quote:
Originally Posted by techman707
They're the same tubes, so whether one would be sharper than the other would be yoke & coil dependant.
If it is the two P16’s in the picture, the guns appear to be slightly different, would/could that also affect the picture quality?

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post #165 of 177 Old 07-04-2005, 10:58 PM
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G70 uses an 08 as well, so is an XG sharper than a G70 ? ;)

Some XG's have 08's fitted at the factory...

But yes, an XG is sharper than a PGx, but it's cause of the electronic centre astig + 6 pole magnets, etc, not the tubes.

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post #166 of 177 Old 07-04-2005, 11:12 PM
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Hi Mark,

Quote:
Originally Posted by Mark_A_W
Ok, now your just getting wacky. A Tor is a pile of rocks.

snip

I guess you can use mm of mercury - that's metric too, but Torr? C'mon you just made that up. (There's a joke here).
Lol. Actually a "Tor" is a gate, but CJ is talking about >torr<. Which would be mm
of Hg. But you can also describe pressure in

- mm H2O (or inches or feet)
- atmospheres
- bar

and for the really crazy in

- kgf/cm²
- lbf/ft²

Of course, we could also talk about "Thor" and the pressure he made, but that
would be totally OT :D :D

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post #167 of 177 Old 07-05-2005, 01:01 AM
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The picture I had in my mind of a Tor is one big rock resting on 2 smaller ones. Depicted in Asterix and Obelix all the time. Technically a hill that had a grave built in it, which is then eroded away, leaving the pile of rocks. Like Glastonbury Tor.

Is that right?

Torii is a Japanese gate.


And yes my joke was that mm of Hg is acceptable, but "Torr" is just plain wacky dagnammit. Stupid wacky units, they designed the SI system for a reason, consarnit.

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post #168 of 177 Old 07-05-2005, 05:30 AM
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"Torr" is most commonly used for describing vacuum levels.

CJ
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post #169 of 177 Old 07-05-2005, 06:18 AM
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Quote:
Originally Posted by Mark_A_W
Is that right?

Torii is a Japanese gate.
Tora, Tora, Tora.........ATTACK!, ATTACK!, ATTACK!........oh, Tori :(

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post #170 of 177 Old 07-07-2005, 10:34 AM
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If you have your edge contrast set wrong it can cause the brightness to look lighter in the center vs outside. Even the magnetics and yoak not placed on correctly can do this.

It sounds like PSI did a poor allightment of the new CRTS.


The newer VDCs have been very good. If you get a new glass VDC I find them better than new tubes in some cases. Pay the extra to get new glass they are just as good or better than new crts. I had amazing focus.

Where you have problems is they use acid to take the old phospor off in rebuilds and if you dont request new glass the acid causes pits or ridges in the glass when they apply the phospor some times not all the phospor can be uneven. If you burn them in for 100 hours they even out more and the focus becomes very good. If you have a huge spot I would think it was a projector problem.

I have had rebuilds that are very good. Rebuilt NEC tubes I allways get new glass on 9 inch marquee they dont burn as much so dont need as much acid. The 9 inch marquee dont make as much difference for new glass vs old glass.

Small spots will be a tube defect 2 inch spot sounds like a defect in install.


Also dont use the projector to verify wear use a blacklight on the blue and sometimes works on green.

Dont blame VDC all the time .. they have provided me lots of excelllent tubes and they have lasted for a long time with out any customer call backs ever.

The color codes of the guns relate to the gun apeature size and the resolution White White is the higest. Where blue yellow is lower.


Greg

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post #171 of 177 Old 07-07-2005, 10:54 AM
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You know your stuff Greg as always

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post #172 of 177 Old 07-07-2005, 12:56 PM - Thread Starter
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The 2" dark spot is on the screen it is maybe an 1/8" on the phosphor.

Ron Newman

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post #173 of 177 Old 07-07-2005, 04:09 PM
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Thanks, Greg.

So which is the smallest aperture indicator color? Yellow, blue, or red? (Pink, actually)

CJ
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post #174 of 177 Old 07-07-2005, 04:36 PM
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Quote:
Originally Posted by GlenC
I need to clarify that my reference to the Blue/White and Blue/Blue on the guns is for the P19 tube and I was only going by the info Charlie told me.

I don't know where this information comes from, but, I can yell you that new P19LUG tubes from a 909 have white and pink.

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post #175 of 177 Old 07-07-2005, 04:54 PM
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I second that. I have a red P19LUG (also ex-Barco) and the runners are white and pink.

CJ
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post #176 of 177 Old 07-07-2005, 07:02 PM
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Quote:
Originally Posted by techman707
I don't know where this information comes from, but, I can yell you that new P19LUG tubes from a 909 have white and pink.
I will third that. P19LUGs that I have seen were all pink/white. The PT-22s (P19 by another name) are white/white. Interstingly the 909s from GL in Hawaii that a friend of mine bought had all original tubes, the reds and blues were P19LUG while the greens were PT-22's. I am guessing that the PT-22 green was used because the P19lugs green are P43 phospher?
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post #177 of 177 Old 07-07-2005, 09:19 PM
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Seems like a reasonable guess. I'd be interested to find out if that's true.

CJ
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