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bigsilverdisc
Joined: 19 May 2007
Posts: 60
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| Posted: Thu Aug 16, 2007 3:03 am Post subject: Rebuilt tubes Any Good? |
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Hi
How can you tell if a projector has rebuilt tubes and is there anything to worry about if they are.
Are rebuilt Tubes just a way of squishing the last lttle bit out if them for a short time or are they as good as new?
Thanks
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Chuchuf
Joined: 11 Mar 2006
Posts: 548
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| Posted: Thu Aug 16, 2007 12:04 pm Post subject: |
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They can be as good as new if they were rebuilt correctly. You just have to try them and see of they focus up correctly.
You can usually tell VDC rebuilds by the brown aqua dag they used in earlier rebuilds. You can also sometimes look at the texture of the phpsphor and see a difference. There is also the VDC sticker on the tube.
Terry
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cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
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| Posted: Thu Aug 16, 2007 11:27 pm Post subject: |
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If the graphite grounding paint on the bell of the CRT doesn't cover everything, you can also get some idea of the tube's origin (new or
rebuilt) by examining the visible phosphor and aluminization on the inside of the glass. You'd probably want to see a few examples
of both new and rebuilt tubes in order to learn how they're different in appearance. But, factory built Panasonic tubes have the phosphor
applied to the CRT face glass BEFORE the face glass is welded to the CRT envelope. Rebuilds aren't phosphored that way. The phosphor
is introduced through the neck end of the CRT bulb (the neck is removed and replaced with a new one with a new electron gun assembly)
and this pretty much ensures that the phosphor on the sides of the CRT face patterns differently.
And possibly the best single way to tell is by the color of the glass on the back of the envelope. (Not the neck.) The glass used for the
CRT bulb has the interesting characteristic of yellowing, darkening, and eventually turning brown as it is exposed to the X-rays that are
generated by the CRT in operation. The face glass and neck glass are a different type of glass and they do NOT discolor with age and
use. So, if the back of the bulb is anything other than water-clear glass, it's almost certainly made from a used envelope, and therefore
must be a rebuilt tube.
CJ
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radar
Joined: 05 Dec 2007
Posts: 72
Location: Sydney, Australia
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| Posted: Fri Nov 07, 2008 11:02 am Post subject: |
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Sorry for dragging this old post up... BUT... am thinking about getting a VDC rebuilt Panasonic tube going cheap for my Marquee. Anyone had any experience with these in their PJ's? Will they last another 10k hours?
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Fri Nov 07, 2008 4:50 pm Post subject: |
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| radar wrote: | | Sorry for dragging this old post up... BUT... am thinking about getting a VDC rebuilt Panasonic tube going cheap for my Marquee. Anyone had any experience with these in their PJ's? Will they last another 10k hours? |
im my experience no, all the rebuilts I ever tried wore the phosphor prematurely and very quickly. A lot of people kept harping about "curing" the tube but it was all BS IMO. no amount of curing would change the fact that it simply wasn't a factory Phosphor coating. A fresh re-built tube would give you a phosphor condition 8 in less than 100 hours.
After that they seem to wear normally though and for 100 bucks delivered to australia it's not a bad deal. Most importantly you'll be getting a fresh gun and new Cathode. Keep in mind a brand new tube is $600. from VDC.
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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 Nov 07, 2008 5:03 pm Post subject: |
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I'll disagree with the 'curing' part. That ALWAYS worked for me, save for the one 9" tube I sent out before I knew about the curing. VDC covered it under warranty.
The problem I had with rebuilds is poor phosphor coating on the tube. I'd always seem to get little black dots, like missing pixels over the tube, usually 2-2 per tube. It always happened after 100-200 hours, not out of the box. I went to Seattle 3X to change out a VDC rebuild on an XG 135LC. I finally changed out to a new tube, no more problems. I talked to Charlie about the problem, he didn't know what caused it.
Note that these dots were tiny, not of the size shown in the 'Tubular' thread.
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Person99
Joined: 09 Mar 2006
Posts: 4899
Location: Flower Mound, TX
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| Posted: Fri Nov 07, 2008 6:07 pm Post subject: |
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| Curt Palme wrote: | I'll disagree with the 'curing' part. That ALWAYS worked for me, save for the one 9" tube I sent out before I knew about the curing. VDC covered it under warranty.
The problem I had with rebuilds is poor phosphor coating on the tube. I'd always seem to get little black dots, like missing pixels over the tube, usually 2-2 per tube. It always happened after 100-200 hours, not out of the box. I went to Seattle 3X to change out a VDC rebuild on an XG 135LC. I finally changed out to a new tube, no more problems. I talked to Charlie about the problem, he didn't know what caused it.
Note that these dots were tiny, not of the size shown in the 'Tubular' thread. |
I don't have your level of experience with tubes. I don't even have draganm's. But I can tell you that on green tubes I did get rebuilt I followed the "curing" process to the letter and they still wore much faster than the factory barco tubes I'd seen.
_________________
Dave
A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station....
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