Television Cathode Ray Tube Electron Gun Evolution (Part 1)
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- เผยแพร่เมื่อ 31 ส.ค. 2020
- Playing with old CRTs always generates lots of questions. I have tried to answer some of these in a series of two videos on the history and construction of common television electron guns. These CRTs all employ electromagnetic defection provided by scan coils or yokes. Heater voltages are generally 6.3V. The video covers both Black & White and Colour tubes and tried to show how to identify pins on the base when no CRT data sheet can be found.
The early colour CRT gun is shown here but Mullard released an excellent film on the manufacturing of this tube, ‘It’s The tube That Makes the Colour’ and it can be seen at: • It's The Tube That Mak...
In this first part, the history of electron gun development is covered along with some common pin connections.
Warning you need to be very interested in electronics and cathode ray tubes to watch these two videos. - วิทยาศาสตร์และเทคโนโลยี
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Thanks for your video, you explain the technical details very well! I have learned a few new details about the CRT gun assembly’s, I shall await part 2!
awesome, watching out for part 2!
Fantastic! I feel I've been let into a secret society and given sacred information :) Mind boggling technology, honestly. Thank you.. Part II or bust! Cheers.
Very interesting! You deserve way more subscribers
Totally agree
Really unexpected to see Marco here.
This is great stuff love it such alot into depth and detail
So super nice work
2:50 is a good way to seperate electrons from protons it seems.
Yes, its quite cleaver, but if the magnet is misaligned or missing no picture appears on the screen.
ooh, TK matic! very good choice!
Excellent
the ion trap works the other way around. The (positive!) ions move towards the cathode where they damage the cathode surface. The trap prevent the heavy ions to make the curve towards the cathode.
Good point, thanks for that, Hadn't thought it through completely. Ions were always blamed for burning the fluorescent screen coating around the centre with with higher impact energy and less deflection but from what you say these would need to have been negatively charged ion. Aluminium backing to the screen coating and removal of the ion trap occurred around the same time suggesting it was a solution. I would expect cathode damage could still be an issue barring improved vacuum processes. Although devastating for the cathode the target area through the grid is small perhaps reducing impacts.
Fantastic
Awesome....
Cool video. I have often been curious if there would be some way to electroplate new emitter material onto a dead electron gun, and restore it, since they are not made anymore.
I think the biggest issue would be accessing the cathode to recoat it without destroying the assembly. The cathode is held in place by numerous spot welds within the grid. As CRTs were expensive items, there once was an industry for re-gunning tubes. Manufacturers would supply new electron gun assemblies for fitting by independent worships.
Could you somehow show the inside of the first gun?
Where the ion-beam hits the inside wall.
Not keen to dismantle that gun as I don't have another, or even another CRT with this type of gun as they are long out of production. I don't think there is much to see and I can see nothing on the inside of the cylinder squinting between the anodes. I wouldn't expect any local noticeable heating as the energy and impact occurrence is small. The fluorescent coating on the screen is easily damaged and even a stationary beam will damage it in seconds, if bright. The Ion burn occurs over long use. I think I have noticed the aluminium coating on the back of B&W screens becoming thin in the area where ions hit, but I can't be sure as it is a long time since I broke up a B&W CRT.
👏🏻👏🏻👏🏻grazie! 👍🏻
Are any of the heaters or enclosures doped by an oxide or radioactive
I haven't found any radioactive coatings used in CRTs. Thoriated heaters are sometimes found in high power valves with heater-cathodes. The cathodes are coated with various oxides to increase emissivity. These become less effective with time and the main reason CRT picture quality becomes poor .
How would you connect the last one up with a positive and negative? What pins go to which one?
It's very similar to the previous socket shown on the Delta gun but simplified and now 3 (RGB) pins are common with just one connection for the grids. All other pins are the same but worth checking the routeing to the pins.
@@tuopeeks Cheers for the quick reply mate, this video has helped me alot.
Is there palladium or silver in those newer( color) guns?
Very unlikely, there isn't a need to use expensive metals in electron guns old or new. Parts mainly need to be non-magnetic. Some later guns may have had small magnetic parts added for convergence.
There is no red color on my TV. It shows black and black instead of red. Could it be due to electrons?
most likely no drive from the red amplifier. Could have a heater out but unlikely.
@@tuopeeksWhich one do you have a picture of?
@@efe794 The video covers the gun construction. The second part goes into more details and pin connections for the later colour tubes with 'in-line' guns. The only connections that are related to the Red gun in later tubes is it's cathode pin. The connection for this is shown in Part 2
Great
I have a question if a new electron was made today to update the technology of it how could you go about doing it?
Good question, the basic principles remain the same. The trend before the end of production was to reduce the size of the gun assembly and simplify the electrostatics/magnetics for convergence. The trend for flatter screens complicated this a little. I think the next development Philips were looking at was to reduce the delay time required for the heater cathode to reach emission temperature. This could produce a more instant picture. While some inroads had already been made for this, there may have been development into cooler cathode emitters, perhaps looking at semiconductor electron emitters or radio-active enhanced emitters. I doubt CRT tech would have much of a revival regardless, as the need for the large high vacuum bulb and high voltage power supplies would still remains making it bulky by modern standards. The closest modern technology spin-off would be plasma displays, but these are now also obsolete.
@@tuopeeks even using diamond moiasstte technology?
@@annfrank5959 Not sure of all the emissive properties of this but it would fall under the banner of semi-conductor emitter.
Thank you for explaining it so beautifully
Can't believe particle ray gun was aimed at our faces up until 2000s kids.
Parent then: don't stare too close to the TV, prolonged use can obliterate your eyes
Kids (adults now): Well no sh*t mom, that what she meant..
Meanwhile buys a curved HD flatscreen*
Fortunately the beam energy is no where near that of a LINAC, so doesn't travel through the screen and air. Interestingly the build up of static charge on the screen, created by the internal acceleration voltage, was high enough to attract and collect dust from the surrounding air.
5v dcv voltage is putting you together Hot Look at some things head to turn on circuit wattage 3w electronic environment