Portable 405 line TV

Saw this little set on a skip and thought poor thing needs some help. Being a portable set, I guess it would not have been used as a main TV therefore it’s working life would be low. Hopefully this meant the tube was good. A quick check with the tube tester showed that after it had awoken from a 50 year sleep, the emission was quite acceptable with a reasonable cutt-off. A slow power up on the Variac and we even had a a station bulb indicator working! That’s a first. Also the mains dropper resistor stack was intact. After quite a few capacitors we got the 10kHz line whistle up (good that I can still here it I guess) and then a raster, showing that indeed the tube was okay. Having sold my 625-405 line converter years ago, I had to connect up my very battered Philips 405 line generator. Not too sure that this is in great health, but will certainly do as quick test. As usual, we had awful linearity with the bottom of the picture cramped and the top stretched out. Normally this is due to DC upsets around the PCL82 frame output valve, but in this case there is more going on. When I have more time, I will have to check further. If I recall, part of the HT for the frame circuit come from the boost side of the line output stage. I will have to check all the high value carbon resistors. Then sort out the sync and I.F. circuits. Always a problem with this Thorn 500 series chassis. I had a Ferguson 506T as a kid and had to wait for the football results on a Saturday afternoon, to try and adjust out the caption buzz. A sound that will be very familiar to TV engineers working in the 50s and 60s. The other interesting thing is, you could always tell if the set was from a smoker’s household, you would end up with yellow fingers. You could also tell if the owners had roast lamb for lunch. That hot waxy, greasy smell!


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