1959 Predicta Tandem - spot suppression?

[john116]

Hi - just wondering if the Philco Predicta's had spot suppression? Turning mine off results in a bright white dot for a number of seconds.

John

[bandersen]

No, they didn't. I don't recall ever seeing a B&W set that did for that matter.
If anyone knows of a model that does, perhaps the circuit could be adapter to a Predicta?

[Electronic M]

One of the 50's TV mags had an article on spot suppression IIRC.

[tom.j.fla]

Use a two pole switch one section for power second section to break the +270 volt connection to the top of the brightness control, that will take the cathode to ground which turns the crt on hard and discharges the high voltage post haste. All the best, Tom

[john116]

Many thanks all! Many Australian black and white TV sets of the late 1950s and early 1960s had a spot suppression/swallower circuit as tom.j.fla suggests above.

[Olorin67]

You could always turn the brightness down just before yu shut it off.

[DaveWM]

I had an old 27" short neck Maggie that used to do that. IIRC I concocted some RC combo on the grid or cathode that would charge up and then after shut down would discharge slowly but keep the tube fully cut off. Pretty simple from what I recall. Pretty sure the reason for the spot is a tube that is way past its prime from reading about it.