A question of rejuvination? - Videokarma.org TV - Video

dtuomi · #1 03-15-2007, 03:03 AM

I took a very old Conrac broadcast monitor with me to a service guy who said he would look at it. Perhaps one of the few in the L.A. area working on broadcast equipment who would look at a monitor more than 30 years old.

Anyway, the picture tube had very little emission to it, and so he rejuvenated it. Now it delivers great performance. In fact, I think I might now have an appreciation of just how good this guy was when he was new.

The question I have is, how long can I expect that tube to last before it becomes dim again, or worse goes out completely?

And how does one get a new tube, especially since Conrac seemed to only stamp a Conrac part number on the tube, and not any kind of identifying number that can be cross-referenced in a book? And since CRT's are banned, outlawed, and not produced, etc.

David

jpdylon · #2 03-15-2007, 11:08 AM

it really depends on how well the CRT responds to the rejuvenation. Some last only a few months, others can last a couple years. Another factor is use. If you plan on using it regularly it might put more wear than you'd like on it.

I've had the best results using a brightner after rejuvenation --especially for tubes that were really weak. However, your mileage may vary.

bgadow · #3 03-15-2007, 12:13 PM

If it was really dim I wouldn't expect a lot out of it. I think it would be good to use it on a regular basis, maybe once a week or so. If they sit dormant too long after rejuvination they seem to lose it.

I would guess that crt would be something fairly standard? If you had the size and degree of deflection you could go from there. You could have that old one rebuilt but that takes $$$.

dtuomi · #4 03-15-2007, 05:47 PM

Quote:

Originally Posted by jpdylon

it really depends on how well the CRT responds to the rejuvenation. Some last only a few months, others can last a couple years. Another factor is use. If you plan on using it regularly it might put more wear than you'd like on it.

I've had the best results using a brightner after rejuvenation --especially for tubes that were really weak. However, your mileage may vary.

I think I might have a problem getting a brightener on basically an unknown tube. The tech guy was able to figure pin out on it by looking inside the glass neck where the wires ran.

However, it did seem to respond very well. And even before it was rejuvinated, the tube would actually produce a picture. It just took 10-20 minutes to warm up.

David

dtuomi · #5 03-16-2007, 12:42 AM

I'm, surprised that no one sported a

But here are the pictures just the same.

David

wa2ise · #6 03-16-2007, 12:50 AM

About 30 years ago I worked for some small toilet of a company that made accessories for CAT scanners used in hospitals. The product was a device that converted video images to hard copy on Xray film. All there really was inside the product was a B&W video monitor, some lenses and shutters and a cartridge that held a piece of X ray film, and some control electronics that would open teh shutter for a fraction of a second to expose the film. Anyway, one of these boxes used a modified Conrac QQA monitor (which could, via a selector switch on its front panel, handle 2 different scan rates. One was 525i, and the other was pretty much 525p. So? you ask... Well we changed the CRT from the 13 or so incher to a small 5 inch flat screen one. Made for a smaller but a flat video image, which was great for the photo lenses and film. No distortions from a curved screen. It was pretty much plug and play. We could have used the orginal yoke, but the company president and marketing guys wanted us to try the "high precision" yokes they got from somewheres. We said we can't promise that it won't blow the chassis up, but okay, if you want to risk it, we'll try it. Could have been a big impedance mismatch. Well, it did work...

I see the pictures of your monitor you just posted, and it looks to be the same vintage and style of chassis as the stuff I worked on above.

Getting a CRT to fit shouldn't be that hard, you could carefully! measure the voltages on the socket pins, these can be upwards to several hundred volts, so use extreme care (but don't measure the voltage on the big fat red wire, that's something like 15000 volts). And compare what you measure to specs for CRTs you can find as replacements.

dtuomi · #7 03-25-2007, 04:50 PM

Well, now I'm disappointed. I've lost sync on the monitor. It had worked fine on the bench, so I rack mounted it back in its place and it just rolls away. It seems to be horizontal. I talked to the tech who rejuvinated the tube and he said that there are a lot of connections on the various cards in the the sides. He suggested that I use contact cleaner on the the 1000 contacts involved and see it if settles out. If not then it might be one of the card's caps gone.

But the question I have now is what do you use to clean 1000 connectors (see the pictures above of the side views)? I have used some stuff on pots called deoxit, but does that work on the connectors?

David

jpdylon · #8 03-25-2007, 05:03 PM

I've used it on collectors before. You can spritz a bit inside the female part of the connector, then insert and remove the card a few times. You can also try 2000 grit sandpaper and burnish up the male pins before the deoxit treatment. If you can tighten the grip on the female pins then all the better.

Just make sure to let everything dry for 12 hours or more before use.

dtuomi · #9 03-27-2007, 12:23 AM

Thanks for that bit of info, I probably would have been a dummy and fired it up right away to see if the spray fixed it.

David

dtuomi · #10 03-27-2007, 12:26 AM

Quote:

Originally Posted by wa2ise

About 30 years ago I worked for some small toilet of a company that made accessories for CAT scanners used in hospitals. The product was a device that converted video images to hard copy on Xray film. All there really was inside the product was a B&W video monitor, some lenses and shutters and a cartridge that held a piece of X ray film, and some control electronics that would open teh shutter for a fraction of a second to expose the film. Anyway, one of these boxes used a modified Conrac QQA monitor (which could, via a selector switch on its front panel, handle 2 different scan rates. One was 525i, and the other was pretty much 525p. So? you ask... Well we changed the CRT from the 13 or so incher to a small 5 inch flat screen one. Made for a smaller but a flat video image, which was great for the photo lenses and film. No distortions from a curved screen. It was pretty much plug and play. We could have used the orginal yoke, but the company president and marketing guys wanted us to try the "high precision" yokes they got from somewheres. We said we can't promise that it won't blow the chassis up, but okay, if you want to risk it, we'll try it. Could have been a big impedance mismatch. Well, it did work...

I see the pictures of your monitor you just posted, and it looks to be the same vintage and style of chassis as the stuff I worked on above.

Getting a CRT to fit shouldn't be that hard, you could carefully! measure the voltages on the socket pins, these can be upwards to several hundred volts, so use extreme care (but don't measure the voltage on the big fat red wire, that's something like 15000 volts). And compare what you measure to specs for CRTs you can find as replacements.

That's actually a pretty fascinating story. I think conrac still makes displays for that kind of purpose. They don't really do broadcast equipment anymore, although I suppose they'd sell you one if you bought it.

There is a list on the back of the chassis of the high voltage cage that basically describes the tube types that are compatible. It doesn't give anything in the way of a part number though, its a list of voltage and deflection parameters that work with it. I wonder if anyone has the schematics for these kinds of monitors. That might give more of a clue as to what wires are attached to the back of the tube.

David