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.

"Jerry Biehler"


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.

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

Know anything about CRT displays ?



..... Phil

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

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?

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.