EMI Push About Coils

[Murphyv310]

Hi.
I've got the set on the bench now and I have noticed that all the valve bases follow a prewar type the later Dickert interference limiter valve base is a post war type. The marking on the chassis is the typical Ekco blue rectangular box with small EKCO a V which is possibly a tick and handwritten 9 39 in it, My TMB has a similar blue box with also a handwritten 11 55 in it as well as a definite tick and EKCO in this box. I'll photo it tomorrow.
I've improved left linearity by replacing the 0.004uf cap in series with the line linearity control, it was severely leaky and dripping wax, I've also replaced some other caps and need to do perished wiring, the tube seems lower than it was a couple of months back but we have the chance of another.

[Murphyv310]

Hi.
Peter, without going OT with this thread I am sure the poor edge focus on the Ekco is down to the tube.
I'll post on the old TSC30A thread what I've done today.

[peter scott]

Hi Trevor,

I took the CRT out of the HMV again today so that I could surround the scan coils with the degaussing coil. I think I got a small improvement in one corner that was worse than the others but it also resulted in a small deterioration of trapezoidal distortion that I had essentially got rid of by external degaussing.

Peter

[Murphyv310]

Hi Peter.
That is odd indeed, I think it could be quite a job to degauss all the metal work on the set. Most degaussing coils don't like extended use and can get quite hot, I've one here as well and you are welcome to use it if you want to alternate between the two.

[Murphyv310]

The interesting things about this set is it has a date stamp on the chassis of Sept 1939 ...

Presumably the first of September 1939, as there would have been no point in continuing to produce the metalwork after the Television Service closed down for the duration ...

I've just realised that war was declared on Sunday the 3rd of September 1939 not the 1st. https://www.independent.co.uk/arts-enter...15621.html
So Ekco employees as it must have been with HMV and others would have reported for work and production would no doubt have continued, there also could have been OT on Saturday and Sunday.

[peter scott]

Hi Trevor,

Thanks for the offer. I think I've done all I can with degaussing and now have turned to another long term problem of unstable RF gain (by which I mean the gain varies). All the voltage feeds are stable but I feel sure it's due to poor contacts on the valve pins. The sockets are not very convincing in that they appear only to grip the pins at the entry point and most of the pin is left without contact. Unfortunately they are not all very easy to access with the chassis in the set.

Peter

[Murphyv310]

Similar issues with the Ekco, the leads from the RF transformers to the SP41 top caps are perishing and short onto the little valve screening cans, also the valves are loose in the bases, both fortunately are easy fixes.