Cathode Ray Tube Projects #1, Testing a Mystery CRT

Today, Labguy takes a break from the cameras and sync generators to play with a really cool compact "picture tube" that he has had stashed away in his junque collection for far too long. Time to fire it up and see if it works or is just another useless nick nack. The tube is the M1234P31 made by Electron Tube Division of General Atronics Corporation. This tube is a cute three inch by three inch blue/green phosphored type that is a mere seven inches deep. Utilizing magnetic deflection and electrostatic focus as well as having an aluminized phosphor screen. This tube would have made a very bright display with a very long service life and low burn in.

Enjoy!

[taecheon]

I just watched your video and made a cheat sheet to get my tube from a B&K tester lit. Thanks much!

[jozefbubez]

Quite a big neck for a small tube!
Using your procedure, we should be able to 'decode' just about any CRT. Thanks!

[RubberChickenFilms]

Spaceballs: The Cathode Ray Tube! Available in most galaxies.

[tarnjp]

Great video, very informative. Thanks a lot.

[YNGBLD]

Hello just came across your video and found it quite informative, I am heading down the tube testing rabbit hole and am after some more information on how to could detect if a tube is allowing air in via a leak. I recently picked up a tube and was told that it was no good due to a leak. It seemed to be arching at the 2nd anode whilst powered up and I could hear the crackling, I had no idea and had a professional advise me of what was going on .I obviously would like to avoid this in the future and am hoping you may be able to shed some light on what to look for and possibly how to test to determine if a leak is present to avoid the above and "ideally" prior to powering the tube up. Thank you FP

[pocketstationman]

Man I hope they make CRT monitors again one day...

[dalekmoore]

OH thanks There Richard i was not expecting my alias to turn up in your video ! ; ), Before had any similar tube data i did the same on this GEC H1025 CRT you are mentioning as in viewing where the pins go just looking studying the nice to know where the heater go's or in this case both heaters .
Having a CRT power supply for the last Anode for these types of crts is something i never thought about that's a handy idea i have a high negative one but not positive.
I had to make my own HV probe using many 10meg half watt resistors and some small PVC pipe...very handy for HV work and saving your Multi meters life !
BTW i was watching a 1940s army video on how CRTs work and they moved the deflection with electrostatic probe from the out side of the tube made me wonder can you deflect a magnetic deflected tube like a electrostatic tube but from home made foil plates on the out side of the tube what do you think ?
Any way Great video Richard posted link on my early television FaceBook page get people interested ! and for me of cause CRT's and image tubes are my interest so you playing around with them is great .

[dannye]

I ran into the exact same problem. I picked up a Toshiba E8069PDA-CD monochrome tube to test some crt driver boards but I can't find any info on the layout of the pins or the voltages for the different parts of the gun.

[tonymoggridge]

Very nice little tube. I expect you have some suitable scan coils for it. Ideal for an NBTV monitor, my special interest just now. My Pickle time base is providing difficult to tame but then if it was easy where's the challenge? Keep up your good work. T.

[jozefbubez]

Be careful not to turn the intesity up too high on an undeflected spot. I have burned screens before!

[ovalwingnut]

M1234 clearly sound suspicious and I would pass on it. However, M12/34 sounds legit and I would impulse buy two! :)

[theallknowingsause]

You know what I found out recently, you can see more subtle screen burn if you get a black light and shine it on a CRT, could you one day or maybe for the future try that out and see if any screen burn exists on those tubes we can't see otherwise