Picked Up An Admiral 27 inch Black and White

[Aperna1985]

Hey, Guys I recently picked up an Admiral Model L2711 Tv with the 20L8M chassis. I made a solid state 5U4, disconnected the high voltage cap from the flyback, and brought it up on my Variac over a period of about 10 hours in 5v increments starting at 25V. Unfortunately, I don't have any B+. I've been watching a lot of Shango lately and I want to try and Resurrect this set before I do a full recap. It would be nice to actually see it work and then check it after each cap I change rather than shotgun it and try to figure out what I've done wrong as I've done in the past.

I've tried to find it in Bietmans for 61-63 and it's not in there. Does anyone else have a schematic? I've had trouble with Sams lately. I got the schematic for my RCA and couldn't read it. I had to call and complain, and wait for them to rescan the original. I know it would make it much easier to have the schematic instead of clipping one lead of every cap at a time and testing with my Heathkit C3, the other option I thought of was using Audio like he does in some early videos.

What do you guys think?

[zeno]

Its nice to see someone use what I think is the best approach.
You are 100% right. The shot gun method often ends in a
more broken set.
Sams is your best option. There are a few still selling original
paper. I do but its too old for my coverage.
These admirals were rugged sets & if it has a good CRT should
come out very nice.

73 Zeno
LFOD !

[dieseljeep]

Originally Posted by Aperna1985

Hey, Guys I recently picked up an Admiral Model L2711 Tv with the 20L8M chassis. I made a solid state 5U4, disconnected the high voltage cap from the flyback, and brought it up on my Variac over a period of about 10 hours in 5v increments starting at 25V. Unfortunately, I don't have any B+. I've been watching a lot of Shango lately and I want to try and Resurrect this set before I do a full recap. It would be nice to actually see it work and then check it after each cap I change rather than shotgun it and try to figure out what I've done wrong as I've done in the past.

I've tried to find it in Bietmans for 61-63 and it's not in there. Does anyone else have a schematic? I've had trouble with Sams lately. I got the schematic for my RCA and couldn't read it. I had to call and complain, and wait for them to rescan the original. I know it would make it much easier to have the schematic instead of clipping one lead of every cap at a time and testing with my Heathkit C3, the other option I thought of was using Audio like he does in some early videos.

What do you guys think?

It looks like it has a separate safety glass!
There isn't that many 27" sets around. 23's and 24's were very popular.
The last 27" I saw was a '65 Magnavox and it was solid state. I replaced the CRT with a rebuilt. It was the first solid state B/W set.

[Aperna1985]

It does have a separate safety glass and I can't tell if it has mold in between or just the glue is separating. The picture with the cardboard underneath is after I cleaned it. If I have all that mold will it be easier to clean up the cataract?

[kvflyer]

Is it color? That would be the reason for the "Cataract" on the picture tube.

It appears to be in Sams folder 593 and I see two sellers on eBay. Downloading from Sams is about the same price but others have complained about the quality of downloads. I have not downloaded any so I can't confirm/deny.

[zenith2134]

Hey,
Nice set. Real nice actually.

Yeah with SAMS photofacts the hard copies are king!

Which CRT does this use? I only ask because I have a few massive yokes in storage which would only fit a large black and white tube such as a DuMont royal. I am planning on itemizing all of my stored parts soon. Lots of treasures in there.

[Aperna1985]

Originally Posted by zenith2134

Hey,
Nice set. Real nice actually.

Yeah with SAMS photofacts the hard copies are king!

Which CRT does this use? I only ask because I have a few massive yokes in storage which would only fit a large black and white tube such as a DuMont royal. I am planning on itemizing all of my stored parts soon. Lots of treasures in there.

It's a 27YP4 tube. Mine is marginal so if you have one to sell I'll be happy to buy a tube from you.

[Electronic M]

Originally Posted by Aperna1985

I know it would make it much easier to have the schematic instead of clipping one lead of every cap at a time and testing with my Heathkit C3, the other option I thought of was using Audio like he does in some early videos.

What do you guys think?

I hope you are actually reading the value printed (or in the case of Sprague Bumble Bees color coded) on to the body of the capacitor instead of using the C3 to tell you value. I've seen plenty of paper caps develop high ESR and measure 2x their labeled capacitance.

Originally Posted by kvflyer

Is it color? That would be the reason for the "Cataract" on the picture tube.

There were NUMEROUS monochrome CRTs in the early 60s to early 70s that used bonded safety glass the same way color CRTs did. I've owned at least 5 bonded safety glass monochrome CRTs and removed a cataract on one. The early 60s Zenith monochrome tubes are the worst because they do something no color tube ever did...They made the safety glass a deep dish such that not only does the glass cover the face of the CRT it wraps roughly 2" around the sides of the tube such that you can't get a guitar string in and the wedge method won't work because the wedges don't lift the glass off the screen.

[Aperna1985]

So I turned the set on just now and started poking around with my meter trying to see what capacitor wasn't producing I poked the circuit breaker and all the sudden the set came on. Granted the spacing isn't great but here it is displaying crosshatch. Unfortunately I did have to hook the brightener up to get it this bright but I'm wondering how much of that is the cataract?

I think that is mold in between. Do you think it will be easier to remove the lense? Because the seal jas been breached? I've never done it before and I'm very intimidated by the idea of removing it. I wish there was someone in NJ who I could take it to.

[Aperna1985]

Please don't disregard the post above, but I shut the set off and turned it back on. The brightener that was on the tube started to buzz loudly, and I only got a dot on the screen Is that common? It's been on this set since the early 70s when it was put away. Does it have caps that dry out inside? I hooked everything back up without it and the TV works again but obviously the picture is dimmer.

[Electronic M]

You have focus problems and vertical problems based on your picture of it running.

Cataract removals are doable. You can see how I do them in this video. https://m.youtube.com/watch?v=F8Wfg1I1Z8Y

[Jeffhs]

It seems to me the brightener could be defective (may have been for years, if it has been on the tube since the 1970s). Removing the brightener must have removed the short or whatever it was which was killing your vertical sweep if you now have a picture again, although if you lost both sweeps at once (but still had HV, which of course means the horizontal sweep must still be working) with the brightener in the circuit, that would seem to indicate the brightener itself is indeed defective.

Your TV also, obviously, has a weak CRT, if the set has had a brightener on the tube for who knows how long. However, before replacing the CRT (I don't know if 27" CRTs are still made today), I would try replacing the brightener since, as I mentioned, it may have an internal short which is killing the vertical sweep. If both sweeps work with the brightener out of circuit, that seems very likely.

Of course, if you are getting only a bright dot in the center of the screen, turn the TV off immediately, and keep it off until you find and correct the problem. Otherwise, the dot will burn itself into the phosphors in the center of the tube, similar to "ion burns" CRTs used to get years ago when the vertical sweep quits. Once this happens, of course, the tube will be ruined forever, as there is no way to repair or undo the damage vertical sweep failure will cause.

[Aperna1985]

Okay so the brightener is definitely bad I hooked it up to my CRT tester just to see what would happen and as soon as I put heater voltage to it it started buzzing away like a bad Transformer. I have two questions one is my brightener says I.E.H. Manufacturing Company New York New York parallel picture tube brightener and then it says cr64 5 wire cr64s 6 wire. I don't have a catalog to look up the brighteners I see on eBay. Is that CR number standard for all brightness?

I was reading through the video Karma page and trying to learn a little bit about the brighteners. A few posts said it's better to rejuvenate the tube after 4 hours of use then keep a brighter on it, is that true? And I see a lot of people don't like the B&K testers for rejuvenating, they're more partial to the Beltron because it is less of a burst. Mine has three rejuvenating settings called Dyn -Low, Med, and High on it is it still has rough as the earlier ones?

[zenith2134]

Originally Posted by Aperna1985

It's a 27YP4 tube. Mine is marginal so if you have one to sell I'll be happy to buy a tube from you.

I don't have any 27" tubes, that I know of. However I have tons of yokes and other parts for the bigger sets. Wish I knew of a new CRT source for you. The big monochrome tubes are pretty scarce.

[zeno]

Brightener has 60cy buzz. Take it apart & probe with plastic. Find a sweet spot & shim it.
More opinions on rejuve than there are weak tubes. I only used modern
B&K, Sencore or Viz. Beltrons were a tester that also had a big
marketing push behind it.
The lower you go the less risk of killing the CRT.

73 Zeno
LFOD !