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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Thu 12, 2019 4:05 pm 
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Matt, do you have the original back for the set?
It should have a bulge or cup in the center to cover the neck of the CRT that should be in the set.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Thu 12, 2019 4:15 pm 
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If the set still has its original back there should be a neck protector cup, just swap the cup for a deeper one....if the set doesn't have it's original back it is advisable to make a new one new CRT or not.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Thu 12, 2019 4:23 pm 
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Quote:
Strange, I don't know how the current was measured. I don't think he has a clip on current probe.


Ah, I probably did this wrong as the amp reading was simply from multimeter when testing voltage of heater pins 1+12. I'm new to this process for sure. What would be the correct way to measure current and on that note should I also be measuring volt readings from the grid connections?

Quote:
Matt, do you have the original back for the set


No it did not come with one. I never actually saw what the back should look like and assumed it was entirely flush with the back since the older picture tube was slim enough to fit.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Thu 12, 2019 6:38 pm 
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Here's what the tabletop version back looks like.

Image


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Thu 12, 2019 6:41 pm 
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Tom Schulz wrote:
MattPilz wrote:
Measured Specs:

Heater Voltage: 6.33
Heater Amps: 0.72

If the current is about right, can the heater really be burnt out?


It would make sense if the tube has gone to air. The filament won't glow because the air is drawing the heat away and the resistance will be a bit lower because it's cooler. So you get a higher current draw and the neck will get quite warm after a few minutes.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Thu 12, 2019 7:16 pm 
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Thanks for the photo bandersen. Something like that should be easy enough to make using hardboard/masonite and plastic containers for the neck part. I figured there must've been some extrusion after reviewing all of the original picture tube specs that were extended beyond the cabinet.

Question: On the replacement tube I notice a couple superficial black dots underneath the tube glass (like a dead pixel on LCD). Is this a common defect in manufacturing or something else? I actually have seen similar with a "dead spot" in a 32" 2000s CRT I picked up but not sure what causes it but is also something not noticable from even a few feet away and at least that one didn't otherwise affect performance. Just want to make sure it isn't something bad.

Question: does it make much sense why the first time I checked it with CRT tester the emissions test came up perfect and cut-off was within normal range...but trying it again last night yielded very low "good" signal that also failed the cut-off test? I did note afterward when checking tester with multimeter that when I had set it to 6.3 it actually was outputting 6.7. I may try the more simple 6V battery test tonight to see what that reads.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Thu 12, 2019 8:01 pm 
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If using conventional test leads you measure current by cutting a wire and inserting the meter in series with the current loop under test. If your meter has a magnetic flux based current probe you need only run the wire through the center.

If you hooked the meter up like a voltage test and switched to current check switch setting it is possible the reading you got was BS that resulted from the voltage measurement leaking to the meter. Most DMMs have 3 terminals: common negative, voltage/ohms positive, and current positive...the voltage terminal has a high impedance (Megaohms) to minimize loading the circuit and the meter changing the reading, current has a low resistance (tenths of an ohm) to avoid limiting current flow which would cause the meter to influence the current in the circuit and change its value. Depending on the cabinet internal switching of the meter it may be possible to have data from the voltage measurement terminals of the meter reach the screen and in current measurement mode....they wouldn't expect you to connect it to measure voltage and set the switch to current.

The inside or surface of the glass in CRTs can have dirt on it prior to phosphor application that will show. Monochrome CRTs have one continuous coating of a single color of phosphor (White), but color CRTs have a mosaic of 3 different colors of phosphor with space between each dot...color CRTs need 3 separate cathodes with 3 separate beams to strike 3 separate color dots without cross-pollination...this is done with a shadow mask each hole allows each cathode to hit a different spot on the screen from the spot any other cathode will hit shining through that hole or any other hole thus implementating separate for channels...the space between was originally blank glass (with a reflective layer of aluminum covering it and the phosphor alike), but later was covered with dark material for enhanced contrast (these are called black matrix color CRTs).... At any rate color CRTs have an 2 additional spot defect causes: black matrix filling in a phosphor hole, and a phosphor dot not being deposited (it gets deposited through a silk screen which has holes that can plug).

There's also chassis derrived phosphor burn holes.... many early monochrome sets and a few color sets neglected to add circuit provisions to switch the election gun off with the chassis....as a result residual charges would run the gun after the deflection collapsed after switch off resulting in a bright dot near the center of the screen for several seconds after switch off the set.... some sets this is harmless, others eventually burn a hole in the phosphor/aluminization.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Fri 13, 2019 12:01 am 
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MattPilz wrote:
Thanks for the photo bandersen. Something like that should be easy enough to make using hardboard/masonite and plastic containers for the neck part. I figured there must've been some extrusion after reviewing all of the original picture tube specs that were extended beyond the cabinet.

Question: On the replacement tube I notice a couple superficial black dots underneath the tube glass (like a dead pixel on LCD). Is this a common defect in manufacturing or something else? I actually have seen similar with a "dead spot" in a 32" 2000s CRT I picked up but not sure what causes it but is also something not noticable from even a few feet away and at least that one didn't otherwise affect performance. Just want to make sure it isn't something bad.

Question: does it make much sense why the first time I checked it with CRT tester the emissions test came up perfect and cut-off was within normal range...but trying it again last night yielded very low "good" signal that also failed the cut-off test? I did note afterward when checking tester with multimeter that when I had set it to 6.3 it actually was outputting 6.7. I may try the more simple 6V battery test tonight to see what that reads.

The thing about making a new back is the hundreds of holes needed for ventilation (cooling). Also unless you go to great pains it won't match the original pattern so it wouldn't be a good restore.
There are ways that you could measure the filament current without cutting the wires. Unsoldering the end of one of the wires where it connects on the chassis or making an adapter to use between the CRT and the existing socket. The main point is that to measure current, usually, you need to connect the meter in series with the filament. If you set the meter for current and connected the leads across the filament you could have blown a fuse in the meter and it will not be able to measure current at all.
It probably is not unusual these days to find a less that perfect NOS CRT, we are probably getting to the bottom of the barrel.
As far as the tester filament voltage, that would have been without loading. Voltages can decrease under the proper load, from the transformer and the wiring resistance. Proper conditions are important for accurate measurements.
That simple 6V battery test is more of a GO-NO GO test, it doesn't give you a reliable number to compare to anything.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Fri 13, 2019 12:47 am 
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Aluminized CRT still requires Ion Trap?

I just realized today that the 21ATP4 aluminized replacement CRT I had ordered (and any other available models I found) still state in the papers that it "is used with a single-field ion-trap magnet."

I was under the impression that aluminized screens did not need an ion trap of any sort. Is it unsafe to run it without, and where might I pick up a single stage ion trap anymore?


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Fri 13, 2019 1:00 am 
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Oh wow. I was looking at past posts and I didn't notice that there is a ion trap.
It is the clamp shaped thing with a coil spring, just in front of the CRT base.
Whether a CRT needs an ion trap or not depends on the construction of the electron gun.
I've seen aluminized CRT that do need ion traps, however later ones do not.
EDIT:
The 21CBP4A does NOT use an ion trap!

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Last edited by Notimetolooz on Sep Fri 13, 2019 1:10 am, edited 1 time in total.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Fri 13, 2019 1:09 am 
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@Notimetolooz Which photo did you see it in, I don't believe mine has one. Just a yoke and centering ring. The dead tube that was in it did not use an ion trap. (One of the images I had posted in the past you may be referring to was from a different user on YouTube who had an identical set but with the original tube that required one).

Quote:
The 21CBP4A does NOT use an ion trap!


The replacement I got is a 21ATP4.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Fri 13, 2019 1:14 am 
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MattPilz wrote:
@Notimetolooz Which photo did you see it in, I don't believe mine has one. Just a yoke and centering ring. The dead tube that was in it did not use an ion trap. (One of the images I had posted in the past you may be referring to was from a different user on YouTube who had an identical set but with the original tube that required one).

You posted a bunch of picture on August 31. I thought that one was yours. You were talking about the centering rings.
You will need to find an ion trap then.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Fri 13, 2019 1:35 am 
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the way you said the crt filament glowed overly bright then burned out sounds like something shorted inside the neck of the crt. i wonder if the rejuvination process blew a bit of metal off the cathode and it touched the filament and caused a heater to cathode short.

you can buy a type of board with holes allready in it. i believe this is called peg board. i had something like that in my old work shop with clips in it for hanging tools. the tool clips could be purchased in a hardware store. once you get the back you cut a hole in it for the neck of crt and put a cap over the hole. it may not match the origional but to much chance of something bad happening without that protection.

when testing a crt leave it hooked up to the tester for awhile as a crt that hasnt been used in years may wake up after awhile. if the reading was in the good you should get a decent if not perfect picture. should be allot better than the old one.

as you read rejuvinating a crt can help in the short term but isnt a permanent fix and can be detrimental to crt health.

i do not know where you could get an ion trap today. you could contact the old service man you mentioned and ask him. since you said he is so friendly he probably wont mind you contacting him. maybe someone here knows. maybe the etf could tell you. to the best of my knowledge a crt with an angled gun that requires an ion trap would not light with the ion trap missing. you would have no raster no picture. a misadjusted ion trap would cause the same problem.

look closely at the gun of the crt. if it needs an ion trap it will have an angled gun. if it is a straight gun it doesnt need one. the part you showed in the pic was your centering rings not an ion trap. least ways i never saw an ion trap that looked like that did and it has the centering rings attached which an ion trap would not.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Fri 13, 2019 3:01 am 
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There are actually three different ways of arranging the gun so that it requires an ion trap (sometimes called a beam bender).
One is to angle the electron gun in the neck so that it points to the side.
A second way is a "bent gun" that has just the rear elements set at an angle.
The third way is a "slant gun" that has one of the gaps between gun elements arranged at an angle.
All three methods result in the electron and ion stream to project at an angle to the neck. Without the
ion trap magnet the stream either hits the side of the CRT envelope or internal portions of the gun.
The magnet bends the electrons back towards the screen or allows the electrons to exit the gun.
The ions are thousands of times heavier than the electrons and so the magnet has little effect on them.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Fri 13, 2019 3:21 pm 
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One thing to be warry of with using the datasheet to confirm Ion trap usage is with regards to rebuilt CRTs....Some rebuilders would put whatever gun they had in a tube....so some tubes that were supposed to have bent guns for ion traps got straight non-trap guns and vice-versa...it helps to visually confirm the gun type before assuming anything.

If need be I can supply a trap off a 10BP4 or 12LP4...I just got 3 such tubes with traps free from a collector who is trying to clean out his TV stuff.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Sat 14, 2019 3:07 am 
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Thanks guys. Attached are photos of the new tube. The neck is completely straight, I'm not sure if any of the inner parts are angled much.

This was a New Old Stock CRT complete with original manufacturer warranty card. There was a note on the box saying that the CRT was composed of all new parts "except for the envelope" which was tested against the specs of a new one (I wasn't familiar with this term but see that is another name for the glass itself).

Quote:
If need be I can supply a trap off a 10BP4 or 12LP4.


Are traps fairly universal? I did find a double ion trap (adjustable) but the specs call for a single and I'm not sure if I can just remove one part of the double and call it good. The spec sheet calls for a an Ion Trap Field Intensity of approximately 40 gausses... which is another measurement I am unfamiliar with how to determine. If you have one you wouldn't mind parting with I'd be happy to pay for it through PayPal etc. you can PM me if you'd like.

Is it ill-advised to run this tube at all before I receive an ion trap?


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Sat 14, 2019 3:48 am 
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the round silver part inside the neck of the crt is the electron gun and it looks perfectly straight to me. that is a straight gun and wouldnt need an ion trap. where you said the tube was manufactured with all new material with the exception of the envelope sounds like that is a rebuilt crt and from the look of it it has a straight gun. no need to worry about ion trap. aparently it was rebuilt and never put in a set,

if you did connect a crt that needed an ion trap and power on the set to the best of my knowledge the only thing that would happen is you would get no light on the crt. it shouldnt damage anything. i worked mostly on late 50s and 60s sets so i didnt see to many that needed an ion trap.


Last edited by thomas13202 on Sep Sat 14, 2019 4:11 am, edited 1 time in total.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Sat 14, 2019 4:07 am 
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MattPilz wrote:
Thanks guys. Attached are photos of the new tube. The neck is completely straight, I'm not sure if any of the inner parts are angled much.

This was a New Old Stock CRT complete with original manufacturer warranty card. There was a note on the box saying that the CRT was composed of all new parts "except for the envelope" which was tested against the specs of a new one (I wasn't familiar with this term but see that is another name for the glass itself).

Quote:
If need be I can supply a trap off a 10BP4 or 12LP4.


Are traps fairly universal? I did find a double ion trap (adjustable) but the specs call for a single and I'm not sure if I can just remove one part of the double and call it good. The spec sheet calls for a an Ion Trap Field Intensity of approximately 40 gausses... which is another measurement I am unfamiliar with how to determine. If you have one you wouldn't mind parting with I'd be happy to pay for it through PayPal etc. you can PM me if you'd like.

Is it ill-advised to run this tube at all before I receive an ion trap?

It is not the neck that would be angled, it is the gun structure in the neck that is angled. In your last two pictures it looks to me as though the gun is angled.
The magnets are not that universal, but you probably can find one that is like the original. These magnets tend to loose their strength over the years, but hopefully the range of adjustment of the location on the neck will be enough. I think ion traps a bit of a pain in the you know where.
On page 62 of this issue of Radio Electronics there is an article on ion traps. I believe there is another article on measuring the strength, but you don't have a new one to compare to so it doesn't help much.
https://americanradiohistory.com/Archiv ... 955-04.pdf
I think you also said you had gotten some publication on TVs, there might be more info there.
I don't think the beam will reach the screen without the magnet. I don't have any to spare.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Sat 14, 2019 4:32 am 
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I realize that people tend not to read much these days, however here is a book that could answer many questions. CRTs are talked about starting on page 219 of the PDF.
https://www.americanradiohistory.com/Ar ... h-1955.pdf

If you absorb this book you will know just about as much as anyone on this forum about how vintage TVs work.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Sep Sat 14, 2019 4:46 am 
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Looking at that last photo, it looks to me that the whole electron gun is installed at an angle. So a ion trap magnet will be needed.

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