A modded Cossor 54

[`FRANK.C]

Hi Peter
I can give it a try but I will have to get reorganised first. I have the cabinet back on the TV after taking the photos.
The EHT generator consists of a rats nest of NE555, 2N3055, EHT transformer, doubler and uA meter all of which are siting on top of the cabinet.

Frank

[Jac Janssen]

Hello Frank,

That's a very good looking Cossor 54!

Congratulations Frank.

I trust you will have a lot of fun restoring it.

(The 54 has always been on my wish list, but I never had the opportunity to obtain one.)

All the best,
Jac

[`FRANK.C]

Thanks Jac
They are a nice set.
As TV's goes they must have one of the lowest components counts.

Frank

[Murphyv310]

110ua should reveal something Frank albeit dull.
I've a VCR97 here if you want it.

[`FRANK.C]

Hi Trevor
Its good to know that 110uA should give some sort of result. Dull is good enough for me .
Thanks for the offer of the VCR97. I may well take you up on it if I need one and if the one that I have isn't up to it. But that's a long way down the line yet.

Frank

[`FRANK.C]

Well I have solved why I wasn't seeing anything on the tube.
I found my VCR97 and hooked it up so the beam current was around 100uA. Just to prove to myself that I was doing everything right and also to see how bright a the unfocused spot would be. And everything worked as expected. See first photo.
I hooked back up the tube in the telly.  I When I connected it I just disconnected the heater, cathode, grid, and final anode leaving the X and Y plates connected.
I had thought that all the X and Y plates should be at the same potential and should be fine. But I was wrong as when I disconnected the X and Y plates and left them floating I got a spot. See second picture taken in darkened room.
It is dim and once it is spread across the screen I doubt it wont be visible at all.


Frank

[Murphyv310]

Hi Frank.
That's good to see a spot. It seems shrouded somewhat. You never know it still may give a picture.
Good luck with the set.
I'm sure if anyone will get it going it'll be you.

[`FRANK.C]

HI Trevor
That was an excellent point and it prompted me to rig up a make shift focus control.
This has made a huge improvement it is looking more promising.
Picture below taken with the workshop fully lit. I left it unfocused. Focusing it makes the spot smaller but as it gets smaller it don't appear to get any brighter.
The spot appears as doughnut shaped. This probably because the EHT is not smoothed and may be modulating the beam.

Frank

[Murphyv310]

I think the CRT will give a watchable picture Frank. When I was mucking about with a VCR97 a few years ago the spot was dull even when it focussed, once it was scanning it got much brighter and was bright enough in a room with normal light. What's the beam current now?

[`FRANK.C]

HI Trevor
Just checked there now as I was not sure and it is still around 110uA.
I get a laugh each time I turn on EHT as the dead spiders stand to attention

Frank