Driving a monochrome CRT Tube

[SGiard]

Big hello to everybody on this wonderful forum and thanks to the guy(s) (and gals?) running it.

Recently I put my hands on an old 9 inch B&W TV. I have always dabbled in electronics and have always been fascinated with the CRT which frankly is a technology that still baffles me. Unfortunately, while

making tests I totally busted the PCB that was driving that tube, but I just can't throw it away. (I guess a lot of people here know that feeling). So now I would like to try and drive it myself just as a

learning experience. I have a couple of old flyback transformers that I know how to drive so the HV part is not the problem. I also do not care about the horizontal / vertical deflection stuff.

My goal is simply to be able to produce a nice white (bluish) dot in the center of the tube.

The problem is I have only the vaguest idea of what voltages I should apply to the pins at base of the neck of the CRT.

I have included a picture of the tube with an insert showing the connector for it.

Here is the pinout of the tube (which is a Matsushita 230ADB4 by the way, I didn't find any specs on the Net and it is not for lack of trying. Does anybody have a spec sheet somewhere?):

Pin 1: Green wire
I know this is the video signal input. I figured that out before busting the board.

Pin 2: Not used, (internally connected to pin 6)

Pin 3: Blue wire
Pin 4: Red Wire
There is very low resistance between those two pins so I think that would be the heater connection but I don't know the range of voltage / current (AC ? / DC ?) I should apply there.

Pin 5: Yellow wire
Pin 6: Orange wire
Pin 7: White wire
These pins are connected to the "electron gun" of the tube.
Pin 5 is connected to the part nearest the pins. (The cathode? Should I put it to ground?)
Pin 6 is connected to the smaller middle part.
Pin 7 is connected to most forward part

Can anybody help me complete the picture?

Thanks in advance...

 

[xelion]

It should be simple enough...?

Hello SGiard.

I now this thread is old but maybe you're still tuned in?

I just signed up at this forum, to try and help you out on your problem. I too have become more and more interested in this particular area of HV electronics, and today I broke off the rear electron-gun-tube from an old colour TV. I was really astonished by the simplicity of this device, and yet, the huge potential it holds!

Regarding the workings of a monochrome electron-gun, there would have to be;

1. Primary operation [3 pins] 5-10kV

1st Anode supply (+) 2nd Anode supply (+) and a Cathode supply (-)​

2. Filament voltage [2 pins] 5V @ 10-15A

Like in a light bulb. A wire is heated creating an electron cloud​

3. Horizontal rectification [2 pins] ?

For aligning the beam horizontally​

4. Vertical rectification [2 pins] ?

For aligning the beam vertically​

As you do not have 9 pins on your gun, I would suspect the H/V rectification has been abandoned for some reason, and perhaps constructed around the big vacuum tube instead. The ANODE is situated at the middle (center in your picture w. the thick wire connected to it), and the rest of the silvercasing is the CATHODE + WENDEHLT PLATE.

I hope this could help you out a little.


Best regards,

Jesper, DK