Inside Macintosh CRT

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Resources

How Products Are made: Cathode Ray Tube
What is Cathode Ray Tube
What is an Electron Gun
Electron Gun (Wiki)
Hot Cathode (Wiki)

Internals

First you will need to remove the tube from the case and disconnect it from the analog board. This is the dangerous part of the job, because the tube will likely contain an electrical charge. You need to discharge it prior to removing the flyback electrode. There is a good video about it and it really works.

To disassemble a Macintosh CRT, first start with removing the deflection yoke. It is very easy, unscrew the ring screw and gently pull the yoke from the CRT. Yoke’s purpose is to scan the electron beam over the screen horizontally and vertically.

Now we should get rid of the vacuum from the tube. Of course I did not do it on purpose. I just chipped the tip of the tube accidentally with the power supply, which made this post possible. But you may do it on purpose. There will be a very small swoosh sound, nothing special and the pressure will be equalised on both sides of the tube wall. No “implosion”. No blow up. None, really.

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For the disassembly of the glass, I used the simplest method: trace the line along which you want the glass to break with a glass cutter, cover everything in some cloth and use a hammer. It works.

A monochrome CRT inside contains two major pieces: electron gun and everything else.

Electron Gun

electron_gun

A: Hot Cathode

Hot cathode emits the electrons. It is built from a very thin like hair filament.

B: Probably a control grid or a pre-accelerating anode

C: Probably a pre-accelerating anode

D: Likely a focusing anode

E: Some other ring

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F: Or would that rather be a focusing anode

Everything Else

The internal surface of the tube is all covered with a silver substance, including the screen internal surface. It is supposed to contain a phosphorescent material, which produces the picture when hit with the electrons from the gun. You can see there is nothing else there – no shadow mask, just the glass screen covered with the phosphorescent substance. Notice the port for connecting the high voltage from the flyback transformer.

Reassembly

No, there is not going to be any reassembly for this post.

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