Ekco TSC30A

[Geordie McBoyne]

Found at last the Polaroid pictures taken during the reconstruction of the cabinet of the TSC30.
The first picture shows the mock up of the lower part of the cabinet. The top part which was the only remaining part of the original cabinet was attached to the bottom part to ascertain the position of the chassis and front controls.
The chassis sits on a sloping shelf so the inclination had to be determined.
The second and third pictures show the new cabinet sides and front panel.
The last picture is of the pre-war Ekco TS701.  The post-war TSC30 is a development of this model.
The Polaroid pictures are badly degraded, taken in 1998.

Geordie McBoyne.

[Murphyv310]

Hi David.
These are very interesting photos. I can see the painstaking work you have done on the set.
Many thanks for posting them up.

[Murphyv310]

Hi.
An update on the Ekco.
Over the last year or so I've occasionally given the set a half hour run. This afternoon i thought it time to concentrate on the set a bit. I have the offer of a really good CRM92 but it involves a bit of a travel, something I don't relish these days like I used to, I do though intend to pick it up once the weather improves.
So when I powered up the set today I noticed how slow the tube was to show even a picture! at this point I decided to try the old trick of passing a small current between grid and cathode to help remove some of the poisoning. Once I removed the back I was rather taken aback to see the getter was quite milky and thought this might be a waste of time.
I decided I've nothing to loose.
I fed the heaters externally and connected the cathode and grid from a variable HT supply from between 60 to 400v via a microamp meter and 270k limiting resistor. initially I tried this with 60v between grid and cathode and there was no current flowing. I then increased the voltage until I got a reading of 10uA, this coincided to 340v so I left it at this. it took just over 2.5 hours to increase to 100uA at which I disconnected the HT and heater supply.
Well on reconnecting it all up there is a marked improvement in warm up time, the picture is brighter but it still gives all the signs of a soft tube but it is now watchable in light although not that bright.
I'd say there is an improvement, whether it will last is anyone's guess. I certainly will take up the offer of the decent CRM92 this year.
I have taken some pictures and will post them up later once I've re-sized them for the forum.
The set need some more work as the line linearity changes after about 30 minutes running but I intend to get the set up to full standard this year.

[Murphyv310]

Hi.
Here are some screen shots as promised.
   
   
   

[Murphyv310]

Hi.
Well looking at the previous pictures I can see the CRT has definitely got worse. Why you may ask and I have an idea. Do you remember that a few years back there was a thread elsewhere about reactivating a CRT without damage. I was sceptical at the time as I had tried it with mixed results. One CRT after a week or so was worse than it was beforehand, I was still on the fence though. So as I had little to loose I did the same to the CRM92 in the Ekco. Initially results were good but after a rest of a few months the CRT is now worse than before.
I have done some work today restuffing caps, replacing wildly out of tolerance resistors and replacing perished wiring. Even though the CRT is low I came to the conclusion the picture was a bit limited with flat whites. A look at the video on the scope with a grey scale showed the peak white and to be clipping badly, it was fine on the SP41 grid, I replaced the valve and double checked all components with no improvement, Then I pulled the vision interference limiter valve and immediately the clipping disappeared. I checked all the components and replaced the limiter valve with no improvement, actually I'm running low contrast anyway and the clipping is still prevalent, I also replaced the DC restorer just in case, so for now the limiter is out of circuit.
I'll nee to fit the 7BP7 Radar CRT for a temporary check to see if the focus is OK and to see if the picture is up to standard. I hope to pick up a good CRM92 soon.

[Murphyv310]

Hi.
Well most of the work is now complete, the 7BP7 doesn't fit the scan coils as its a thicker gun than the CRM92 so that idea is out of the window. Once all the perished wiring is done I'll take some more photos for here and the Radio museum.

[Geordie McBoyne]

Like many post-war TV sets the Ekco TSC30 is a pre-war design.   The concept for the chassis dates back to 1938 in the form of the model TA201 vision only receiver.   The output from the sound demodulator has to be supplied to the pick-up sockets on a radio receiver.
The TA701 emloys a 7" Mazda CRT, type CRM71.
The first Ekco TV sets were made in 1937.

Geordie McBoyne.

[Murphyv310]

Hi.
You can see the results from the recent work in the pictures. The focus isn't too bad at low brightness and contrast but the focus is not so good on the left hand side of the screen, if you juggle the focus coil and position it differently in relation to the gun it will de-focus on the RHS instead. The CRT has been regunned in the past and laying a straight edge on the gun it is out by a couple of degrees so all the focus issues in my opinion is purely CRT based. I did try the CRT on the B&K and it was showing leaks from all electrodes, a sure sign the CRT is gassy.
I've strapped the SP41, top screening caps together and to earth and you can see the result on Franks converter switched to 5:4, very good indeed.

           

[Murphyv310]

Hi.
After a bit of heaving around the chassis is now back in its cabinet.
Very pleased with the work and now just waiting for the CRT, this can be done without removing the chassis so less work required.
Here is a picture of the TSC902 from 1939, the chassis and cabinet to me looks the same as the TSC30A.
   

[Geordie McBoyne]

Hi Trevor,
same cabinet shape, just a darker finish. Looking at that picture it would appear Ekco was expecting big sales for the TSC902.


Geordie McBoyne.