1950's RCA TV.... Picked this up today.

[Magnavox300]

Bought this set for $40.00 today.
Don't know anything about it, except that it looks very cool.
I know it's not good to turn it on, but I did, all the tubes lit, no screen.
Hope the CRT is okay, looks like there is a black spot on the glass, I don't know if thats a common red flag showing a bad CRT or not.
I wasn't informed of it till I handed over the cash!
I told the guy nicely, " you could have mentioned that before we made the deal", but that I would fool with it and see. Maybe it's just lots of dust, well, when I can figure out how to remove the glare cover, then I'll know.
I did hear crackling in the speaker though.
This also has the back cover, and is complete. Doesn't look like anyone touched it for years.

Anyone ever work on one of these before? It has a huge chassis, can't wait to clean her up and recap it all, just want to be sure the CRT is decent before I do anything else.
What I really need now is a CRT tester? I think it's called, I wonder what type is good?
Would it tell me if this CRT is good or shot?
Also, Is the tube in the HV cage supposed to be lit when the set is powered on? It wasn't lit.

[kvflyer]

At first, I thought that the CRT had been "necked". But on closer examination, it just looks like typical dirt that accumulates because of the electrostatic attraction. A good Windex job will most likely fix that problem.

Do you know anyone with a CRT tester? Don't know where you live (City or State).

[Phil Nelson]

One good model of CRT tester is a Sencore CR70. There are many others out there, but be aware that a vintage tester may require the same sort of restoration as anything else that old.

A CRT tester may cost more than you paid for your TV. If you have a multimeter, you can at least test the filament to find out if your CRT is a total dud. This article explains how:

http://antiqueradio.org/FirstStepsInRestoration.htm

The rectifier tube in the HV cage is a 1-volt tube and you won't see it glow (if at all) unless the room is totally dark.

If you skim a couple of the TV restoration articles in this section, that should give you an idea what's generally required to make these old TVs work:

http://antiqueradio.org/restoration.htm

Be careful around high voltage, as noted many times in those articles.

I would not play the TV for extended periods until you have replaced (or at least checked) the electrolytic capacitors in the power supply.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[Sandy G]

I don't THINK the CRT has lost its vacuum-Just typical dirt accumulation over nearly 60 years of use, as mentioned by Kyflyer. The cabinet LOOKS to be good, maybe indicating it came from a good home.

[Jeffhs]

I agree with everyone on this. If the CRT had been necked (meaning the neck was literally knocked off the back of the tube), accidentally or otherwise (!), air would have rushed in and blown the phosphors off the center of the screen, leaving a much larger spot than your set shows. Run the usual emission test on the tube; perhaps you won't have to replace it. Many times these old CRTs will have a surprising amount of life left in them; depends on how much the set was used.

[Magnavox300]

Originally Posted by Phil Nelson

One good model of CRT tester is a Sencore CR70. There are many others out there, but be aware that a vintage tester may require the same sort of restoration as anything else that old.

Thanks, I will look for a Sencore. I Just bought 3 sets this week, and all have "No Picture", so I definitely need one.
I have looked at your site many times, but didn't know that was you!
You have great information on there Phil, thanks.

[Kevin Kuehn]

I love the looks of these mid 50's RCA consoles. I guess some collectors feel they're sort of ho hum, but cabinet style wise they look just as nice as the early color sets. So what chassis does this set use? Looks like a lot of fun for $40.

[Dan Starnes]

Good score!!

[radiotvnut]

In addition to the Sencore CR70, there are also several B&K models (467, 470, 480, and 490) that are decent. The 467 and 490 have three seperate meters for better evaluation of color CRT's. The 470 and 480 models have a single meter and a knob to select between R, G, and B color guns. The models that I mentioned also have a decent rejuvenate function that will be less likely to harm the CRT than older testers. These testers cost a lot of money when new; but, can now be obtained cheaply if you look hard enough.

If all you want to do is evaluate the condition of older B&W tubes; then, pick up an older B&K tester from the '50's or '60's. The blue cased 465 is a good tester for testing B&W and older color CRT's; but, the rejuvenate function is rather crude and will often do more harm than good when attempting to rejuvenate a weak CRT. The older CRT testers sell for next to nothing and are often free. My first CRT tester, a freebie from a shop who no longer used it, was a B&K 465 (early '90's).

[n2bew]

Originally Posted by radiotvnut

....... The 467 and 490 ...... The 470 and 480..... The models that I mentioned also have a decent rejuvenate function that will be less likely to harm the CRT than older testers....... The blue cased 465 is a good tester for testing B&W and older color CRT's; but, the rejuvenate function is rather crude and will often do more harm than good when attempting to rejuvenate a weak CRT. (early '90's).

I have a B&K 466 in a black case, would you include that as one with the crude rejuvenate function that I probably should not use?
I have not had a bad CRT that I thought about using it on yet.... , but would like to know for future reference.
Thanks, Tom B.

[radiotvnut]

Yep, the 466 is the last of the crude ones. It will check an older tube just as good as a newer one; but, it's rejuvenate feature is rather crude. I will admit to rejuvenating quite a few B&W tubes with my old 465 and some tubes held up, others didn't. I didn't have near as good of luck with color tubes. My newer 470 model does much better at rejuvenating tired CRT's. Of course, there are some tubes that are so worn out that no tester will help them; but, I find that the newer testers have a higher success rate. Even with the newer testers, I won't rejuvenate a tube unless it checks very weak and/or displays a lousy picture. If it looks acceptable, I leave it alone.

[n2bew]

Originally Posted by radiotvnut

Yep, the 466 is the last of the crude ones. It will check an older tube just as good as a newer one; but, it's rejuvenate feature is rather crude. .......

Thanks for the info. At least it was cheap, and it works quite well for checking CRT's so I will stay away from THAT button unless it is an absolute last resort and just use the "cook" method with just running a little higher voltage for a while to try and help weak emmissions if I need too.
By the way would that also apply to the remove short functions?
Thanks,
Tom

[radiotvnut]

The remove shorts function on my newer tester seems to work the same way as the older ones; so, I'm not as worried about that feature.

My old 465 had three levels of rejuvenation; as I think the 466 does. If you have to rejuvenate a tube, start out at the lowest level. If that does not work and if the tube is otherwise not watchable, move up to the next level. A lot of guys thought along the "more is better" line and they'd start out at the highest setting. This method is very dangerous and is very likely to ruin the CRT. When rejuvenating a tube with one of these testers, hit the button for a split second and release it.

My 470 has remove shorts, clean and balance, and rejuvenate functions. The remove shorts function is for removing K to G1 shorts, the clean/balance function is for use on color tubes where all three guns may check "GOOD"; but, one gun may be low enough to prevent proper tracking with the other two guns. The rejuvenate function is for tubes where one (or more) guns show an emission level that's in the "BAD" range.

Just to be safe, I start out by using the clean/balance feature on tubes that actually check bad. Most of the time, that's all that's needed to bring them back up. If that does not work, I proceed to the more powerful rejuvenate setting. On these testers, you hold the button down, at which time you'll normally see the meter rise. You continue to hold down the button until the meter falls back down. If the meter rises a good bit up the scale and remains there for a few seconds before it falls down; then, the tube will likely rejuvenate well. If the meter barely moves up the scale and then falls back down quickly or if the meter does not move at all; then, the tube either didn't rejuvenate at all or will not likely last long.

[mstaton]

I bought a Sencore CR31A on ebay for around $20. It came with all the adapters. One unique feature is the built in HV tester. Very handy to have and one less thing to carry. The tube setup book is from 1990. Tests most all CRT's except electrostatic. Just goes to show that you can get a good cheap tester.

[n2bew]

Thanks for all the info on testers. Sorry to temporarally hijack the thread, although it was at least on topic.

Now back to our regularly scheduled program....