CRV59-AAE Military Iconoscope Camera restoration

[dtvmcdonald]

I've tried grounding the collector ring with a screwdriver. I've also
tried putting + or - 9 volts on the unused pins which attach to
the Cesium dispensers, and they don't do much if there is no
hum on them.

I've tried using a magnet to move the electron beam over to the
side where it hits beyond the edge of the silver dot area.
This generates a very strong signal which lasts a lot longer.
Its currently cooling down so I'll try that again.


It does seem thermal, but why cooling down much faster than
warming up?

Edit: a new try shows that the actual picture lasts much longer,
at any setting of the bias, at the far left of the screen.

[old_tv_nut]

Originally Posted by dtvmcdonald

...
Edit: a new try shows that the actual picture lasts much longer,
at any setting of the bias, at the far left of the screen.
...

Well, this just gets more and more puzzling.

Do you have anyone who can review the wiring with a fresh eye in case something got missed when you recapped?

[dtvmcdonald]

I discovered by accident that even if it runs 5 minutes beyond the
picture disappearing, and I then turn off all power for 5 seconds and then
back on again, as it re-warms up for a couple of seconds an excellent
picture appears, just a bit small, lasting just an instant as it gets
full size.

This would seem to be a bias drift problem.

I spoke to Schechter last night on the phone. Amazingly, he only knows
of himself, McVoy, Aussie Bloke, the Japanese genius with the perfect
transistorized picture, and me, with 1846 cameras working at all.

Do you know of more?