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Old 06-05-2014, 01:07 AM
EdKozk2 EdKozk2 is offline
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WTB: Blue CRT Projection Tube Zenith PV-800

Hi,
I'm looking for the blue crt for a Zenith PV-800p front projection monitor. The monitor was manufactured in February of 1985.My son and I bought the set at our local Goodwill for 4 dollars. We tested the set right there in the store. All three crt's lit up, so home the monitor went. The monitor had a couple of cracked red crt lens mount flanges, which caused a convergence problem. I rotated and shimmed the lens housing then reset the focus for the red crt. I visited Curt Palme's Projection TV website for some set up info. I got the monitor into somewhat usable shape.
The Red and Green CRT are still fairly strong, but the Blue CRT just isn't bright enough any longer. I even swapped crt connections between the green and blue tubes. There was no improvement with the blue output. Switching G2 Screen jumpers don't really correct the problem. The blue tube seems to be lacking luminence. Also all blue scenes such as a blue sky are greenish or reddish depending on tint control setting.
If anyone has a useable blue crt with low hours on it to trade or sell , PM me.
Thanks,
ED
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  #2  
Old 06-05-2014, 04:13 PM
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rca2000 rca2000 is offline
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I would be VERY careful here. You WILL have a LOT of trouble balancing the new tube to the old ones. Grey-scale will be IMPOSSIBLE---to get right. I speak from experience here--on many projos --including this very model. These sets were NOT that bright to begin with--compared to the later ones.

Your only real option is to replace all 3 tubes--with good ones. They do not have to be new--but they have to be nearly EQUAL. All new--or all old, but good.
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  #3  
Old 06-05-2014, 04:29 PM
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Jon A. Jon A. is offline
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Aw, I was hoping that these were coffee table-styled like Tim's Fony. I would be keeping my eyes open even for a non-functional unit.
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  #4  
Old 06-06-2014, 12:56 AM
EdKozk2 EdKozk2 is offline
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Quote:
Originally Posted by rca2000 View Post
I would be VERY careful here. You WILL have a LOT of trouble balancing the new tube to the old ones. Grey-scale will be IMPOSSIBLE---to get right. I speak from experience here--on many projos --including this very model. These sets were NOT that bright to begin with--compared to the later ones.

Your only real option is to replace all 3 tubes--with good ones. They do not have to be new--but they have to be nearly EQUAL. All new--or all old, but good.
Thanks for the words of caution. I figured that even a crt with 5000-8000 hrs on it could be better than the one I have in there now. The current blue crt is only half as bright as the green or red crt's outpout. I covered each lens to get an idea the individual crts brightness. The blue focus is terrible. I agree that the color balance / gray scale is most important , not the over all picture brightness.
I think you had an old post on this projection set a few years ago.

Ed
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Old 06-06-2014, 12:59 AM
EdKozk2 EdKozk2 is offline
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Quote:
Originally Posted by Jon A. View Post
Aw, I was hoping that these were coffee table-styled like Tim's Fony. I would be keeping my eyes open even for a non-functional unit.
JON,
What is a Tim's Fony ??
Ed
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  #6  
Old 06-06-2014, 02:02 AM
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Kamakiri Kamakiri is offline
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I think he's talking about my KP-7220 and hit a wrong key

http://www.videokarma.org/showthread.php?t=261265
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Old 06-06-2014, 02:33 AM
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Jon A. Jon A. is offline
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Yeah, but that keystroke was done deliberately. A blanket statement really, but they did produce some serious duds.
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  #8  
Old 06-06-2014, 11:41 AM
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NoPegs NoPegs is offline
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Have you considered a brightener of some sort? Tweak the HV a bit, juice up the filament by 18-23%, maybe handicap the Green and Red tubes so they're slightly dimmer?

I'll bet somewhere there's a set of all 3 in some TV repair shop's storage that nobody even remembers are there. Eventually they'll wind up on eBay or in the dumpster. Hopefully eBay.
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Old 06-06-2014, 04:23 PM
EdKozk2 EdKozk2 is offline
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Quote:
Originally Posted by NoPegs View Post
Have you considered a brightener of some sort? Tweak the HV a bit, juice up the filament by 18-23%, maybe handicap the Green and Red tubes so they're slightly dimmer?

I'll bet somewhere there's a set of all 3 in some TV repair shop's storage that nobody even remembers are there. Eventually they'll wind up on eBay or in the dumpster. Hopefully eBay.
I did try adjusting the green and red drive on G2, doesn't really do the trick. The PV 800 isn't set up for individual HV adjustment as far as I can tell. If I had the schematic / service manual to this monitor it might help. I will be on the lookout for another parts set too.
Ed
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  #10  
Old 06-07-2014, 12:55 PM
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rcaman rcaman is offline
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i have never seen a good one of those zenith projectors. crappy pictures and the tubes went down pretty fast. i think your are wasting your time on the set. but i have wasted a lot of time on sets also. good luck
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  #11  
Old 06-07-2014, 02:34 PM
zeno zeno is offline
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A few cheats.....
Try rejuvanating
Try a brightener. You need to find out if it uses a horz winding
or off a regular transformer 1st !
Look for a very low ohm resistor in series with the fillament & jump it
out.

Some risk in any of the above but what you got to loose ?

73 Zeno
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  #12  
Old 06-07-2014, 09:15 PM
EdKozk2 EdKozk2 is offline
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Thanks for all the tips and advice everyone.
I never tried rejuvenating or adding a brightener to a crt.
ED
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  #13  
Old 06-07-2014, 09:32 PM
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rca2000 rca2000 is offline
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Problem here is often--Projo tubes not only get a waek GUN...but the PHOSPOR also degrades--from the heat produced. SO--while it might help some...if the screen is dying it might not...

I recall hitting HARD_-some tubes in an old I think Mits set for a guy--and I TOLD Him--it would not hold. It helped enough I guess--but i did not figure it would last. It did NOT. After a couple of days...they all three were dim and blurry again. NO problem right ? just tell the customer the truth---we tried to restore the tubes--but they are too far gone. You need new set.

Well...that WOULD have been the case....EXCEPT this IDIOT LIED to the customer--and said he had REPLACED the tubes !! He charged something like $500 for the job--(this was the fall of 1995 or 6 IIRC) which would NOT have been NEARLY enough. for the tube cost ALONE--but he could spin a lie like NO one i have ever known. The customer was NOT happy when the tubes died again...but he just IGNORED them....and after a few more incidents like this...he skipped town. One such job was a bad yoke on another projo --he sliiconed it and it DID work--for a few days...then....

Yes--he DID have a bad drug habit......and in 2007....it killed him...
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