Picked Up An Admiral 27 inch Black and White

[Aperna1985]

So good news I rejuvenated the tube on Dynamic low and it went from a very weak reading to almost a full reading. The picture looks better than it did with the brightener now. Looks like it's time to start buying capacitors.

[zeno]

Remember a few at a time then test as you go.
Good luck
Zeno

[DavGoodlin]

Originally Posted by Aperna1985

So good news I rejuvenated the tube on Dynamic low and it went from a very weak reading to almost a full reading. The picture looks better than it did with the brightener now. Looks like it's time to start buying capacitors.

I destroyed a weak GE 21ATP4 by weld-shorting elements.
Using my BK445 on dyn hi when it barely moves the needle on emission at 12 volts on filament,
white hot and no cathode dust left. Now a neon-glowing on both halves with a short
Using Dyn Hi is the last desperate move after dyn lo and dyn med failed to restore emission.

Admiral BW tubes from 50s-60s were always decent and responded to a light touch

So glad you had a good experience. I have a 27" Muntz with a no-name rebuilt 27EP4 and a Beltron in for repairs.

[Aperna1985]

Originally Posted by DavGoodlin

I destroyed a weak GE 21ATP4 by weld-shorting elements.
Using my BK445 on dyn hi when it barely moves the needle on emission at 12 volts on filament,
white hot and no cathode dust left. Now a neon-glowing on both halves with a short
Using Dyn Hi is the last desperate move after dyn lo and dyn med failed to restore emission.

Admiral BW tubes from 50s-60s were always decent and responded to a light touch

So glad you had a good experience. I have a 27" Muntz with a no-name rebuilt 27EP4 and a Beltron in for repairs.

Your experience is exactly why I was so afraid to try and rejuvenate my tube. Out of curiosity do you know who made the tubes for Admiral in this era?

[dieseljeep]

Originally Posted by Aperna1985

Your experience is exactly why I was so afraid to try and rejuvenate my tube. Out of curiosity do you know who made the tubes for Admiral in this era?

They had several firms that they bought their CRT's from.
It looks like the one you have is a Thomas, IIRC EIA 672.

[Aperna1985]

So I hooked a VCR To the Set and its working surprisingly well, with the exception of being a little blurry. I'm wondering if that is just because I'm looking at the image through a lense that looks like a glass of milk. I've watched a ton of cataract videos this week. It seems I have the RCA style Cataract. I'm probably worrying too much about this, but I'm afraid to ruin an unobtainable tube. It seems there are 2 methods to remove the PVA either a ton of heat, or soaking it in water or vinegar and water for months on end. What is the best way to do it? I read one post that guy used those heat lamps they put food under to get it loose, I've seen people use plastic bags and put it in the sun, I've seen halogen lights, is there a fool proof way? Has anyone tried soaking it in a solvent first to soften it? Like Acetone, gasoline, diesel, laquer thinner, etc. Then apply heat? Or maybe pick out all the edges or do the guitar string like Tom C then soak it so the water gets in easier? I really think I'm over thinking this, and probably being over paranoid, but I really like this set and I'm afraid to implode or ruin that tube some how.

[Electronic M]

Your tube seems to have a focus problem more so than a cataract problem based on what I see in the pictures. I'm not saying the cataract isn't contributing to it (it surely is), but I would probably try to electrically improve focus first.

For an RCA cataract removal there's safe and there's effective which are 2 different things. The water method is very safe, but unless the tube has delaminated all or almost all the way to the center has been completely ineffective when I have tried it. The guitar string method is safe and on all Zenith and maybe 10% of RCA tubes effective. Ninety percent of RCA tubes seem to have too hard of a glue to be effective. The heat method is dangerous but highly effective....The danger is not using enough finesse. If the heat on the face is uneven and applied too fast (should be heated gradually over hours of time) the tube will fracture or implode. Also wedges are needed wit the heat and if you push them in too hard it's easy to crack the safety glass...If you crack the safety glass you can still salvage the tube but you have to suffer the glass shard hell of chipping off the safety glass with a hammer and chisel (did that probably 10 times before I got a heat gun which combined with the sun got me to a point where I could reliably get the safety glass off intact).

Others probably have their own oppions.

[dieseljeep]

Originally Posted by Electronic M

Your tube seems to have a focus problem more so than a cataract problem based on what I see in the pictures. I'm not saying the cataract isn't contributing to it (it surely is), but I would probably try to electrically improve focus first.

For an RCA cataract removal there's safe and there's effective which are 2 different things. The water method is very safe, but unless the tube has delaminated all or almost all the way to the center has been completely ineffective when I have tried it. The guitar string method is safe and on all Zenith and maybe 10% of RCA tubes effective. Ninety percent of RCA tubes seem to have too hard of a glue to be effective. The heat method is dangerous but highly effective....The danger is not using enough finesse. If the heat on the face is uneven and applied too fast (should be heated gradually over hours of time) the tube will fracture or implode. Also wedges are needed wit the heat and if you push them in too hard it's easy to crack the safety glass...If you crack the safety glass you can still salvage the tube but you have to suffer the glass shard hell of chipping off the safety glass with a hammer and chisel (did that probably 10 times before I got a heat gun which combined with the sun got me to a point where I could reliably get the safety glass off intact).

Others probably have their own oppions.

Try removing the CRT and investigate. All the 27" sets of that era had a separate safety glass. The 27" tubes were falling out of favor at the time.

[old_coot88]

Originally Posted by Electronic M

There were NUMEROUS monochrome CRTs in the early 60s to early 70s that used bonded safety glass the same way color CRTs did.

I'm embarrassed to say for all the years in the trade, I never knew there were BW CRTs with bonded faceplates. No doubt they went through the shop, but for issues other than jug replacement.

[Tom9589]

We had a B&W 23" Sylvania, purchased in 1960, with a 110 deg bonded safety glass CRT. I guess cataracts weren't a problem back then as most CRTs didn't last long enough to form cataracts. Good TV, but the original CRT only lasted 4 years.

Here's a good question. What did CRT rebuilders do with the bonded safety glass during the rebuild process? Did the just leave it alone during all the baking? I don't remember ever reading where they removed the safety glass, rebuilt the CRT and then re-applied the safety glass.

Curious minds want to know....

[old_tv_nut]

I believe neither type of bonding material would survive the baking.

If heating the face just enough to remove the bonding is dangerous, it seems the baking process would be a disaster for the tube as well as the bonding material, no?

I don't know if all rebuilders had a way to rebond the faceplates, maybe only the OEMs? It would be interesting to find out

[Jeffhs]

Originally Posted by old_tv_nut

I believe neither type of bonding material would survive the baking.

If heating the face just enough to remove the bonding is dangerous, it seems the baking process would be a disaster for the tube as well as the bonding material, no?

I don't know if all rebuilders had a way to rebond the faceplates, maybe only the OEMs? It would be interesting to find out

I agree.The bonding material may not and probably would not survive any kind of removal procedure involving high temperatures.

As rare as 27" CRTs seem to be, I wouldn't even try to remove the safety glass; there is too great a risk of damage to the tube. I don't know if the Admiral TV you have would or could use a smaller tube, say 23 inches (differences in things like deflection angles and, of course, the physical size of the tube; the latter could be a problem since the mask, not to mention the mounting itself, would be four inches too large, leaving an unsighly gap between the edges of the tube and the CRT mask itself), but it might be worth a try if you can somehow compensate for the difference in screen sizes.

BTW, yours is the first TV I have ever seen with a 27" CRT (I have never seen a set with a CRT this large in person in my life). Most televisions I have ever run across used CRTs no larger than 25 inches. (I once had an Admiral "Microgrid 390" 23" console TV, but this set had the largest CRT I ever saw in a b&w TV.)

Why Admiral decided to use a 27" CRT in any of its TVs is a mystery to me, unless they wanted to see how well a set with a tube that big would sell in the 1950s; after all, no other TV manufacturer, except perhaps DuMont, ever came out with a TV using a CRT this big.

My best guess is those sets did not sell very well, which could have been one of several reasons Admiral went out of business when it did. It has been mentioned in VK that Admiral televisions had a lot of problems, not the least of which had to do with HV regulation, even in their b&w sets. I had an uncle who replaced a 23" Sylvania console TV with an Admiral 17" (IIRC) color portable in the 1970s; the latter seemed to work well, with no major problems I was ever aware of. This may have spoken well for the quality of Admiral TVs at that time, but the quality of these TVs went downhill fast shortly thereafter.

This could and probably would explain why the company went out of business when it did, although there was a Japanese or Chinese firm which might have tried to revive Admiral in the early '80s. This firm was known as AOC, for Admiral of China. I don't think AOC's televisions (if the company ever made a color set) were much good, however; if they had been, AOC might still be in business today.

[Tom9589]

IIRC Magnavox offered 27" B&W TVs for a number of years in the 1950s.

I currently own a 36" Sony Trinitron. Talk about heavy and bulky. It weighs more than I do!

[jr_tech]

Originally Posted by Tom9589

IIRC Magnavox offered 27" B&W TVs for a number of years in the 1950s

Zenith made a nice 27 inch set in the mid 50s.
http://www.tvhistory.tv/252KA21A5.jpg

jr

[Tom9589]

Interesting.... Look at the model name of this Zenith: Sovereign.