Small monochrome CRT monitor issues

Aug 03, 2011 2 Replies

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Jerry Biehler 14 years ago

Lets try this again. Cmon, google, post!

I have a little 4.5" monochrome CRT Display in a deposition controller I have. It runs on 12v and uses NTSC. Pretty generic.

Its Dead.

I have high voltage, getting about 260v to the screen grid, filament is glowing. Scope shows activity on horizontal and vertical deflection. I can see the amplified video signal at the cathode on the tube.

What am I missing? Not enough HV? Poisoned cathode?

Checked the video output with another display and the video is good. If all else fails I will just run an external display.

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Phil Allison 14 years ago

"Jerry Biehler"

** As already suggested by Ian - you likely have no EHT.

Know anything about CRT displays ?

.... Phil

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Franc Zabkar 14 years ago

On Wed, 3 Aug 2011 12:18:07 -0700 (PDT), Jerry Biehler put finger to keyboard and composed:

glowing. Scope shows activity on horizontal and vertical deflection. I can see the amplified video signal at the cathode on the tube.

If you hold the scope probe near the face of the CRT, do you see a flyback pulse?

Does the FBT have a stick diode in its EHT lead?

- Franc Zabkar

Please remove one 'i' from my address when replying by email.

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