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Old 23rd Aug 2017, 11:59 pm   #71
1100 man
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Join Date: Apr 2016
Location: Ventnor, Isle of Wight, & Great Dunmow, Essex, UK.
Posts: 1,377
Default Re: Pilot PT650 "Spacemaker" Television

Many thanks Paul, Tony & Oliver for the encouraging comments
I must confess, I'm pretty happy with it myself- I think when it's all finished, it should look much like it did when it left the factory! That's my goal anyway.

I've reached an important milestone tonight- The valve heaters are lit for the first time!!
The original mains dropper was totally knackered so I've hooked up a temporary one with the correct resistance for 240V mains- In the 21st century there will be no requirement to run it of a wide variety of voltages although in my experience (as an electrician) the mains is usually about 245V and occasionally nearly 250V.
Currently, here the mains is 244V and the heater current is 305ma. The voltage across the CRT heater is 12.10V so all pretty much spot on.

Hopefully, tomorrow night I can wire up the HT rectifier. The original metal rectifier had been replaced with an ancient diode and series resistor mounted on a bit of tag strip. It looks like it was done a very long time ago so the metal rectifier must have failed quite early on in the set's life.
I will use a new piece of tag strip and a BY133 with a 1000pf 1000V cap in parallel with it. I have increased the value of the mains dropper by 25 ohms or so but will probably have to play around with the value to get the HT about right.

I also plan to give the LOPT a gentle cooking to drive off any moisture. I did the overwind a little while ago but I will do the primary as well just to give it the best chance of survival.

So if all goes well, this time tomorrow night we might just have a raster!! (LOPT willing of course!) I've still got various things to attend to on the IF board and the tuner from a wiring point of view so actual pictures are still a few days away but it's all getting very exciting
Watch this space!
All the best
Nick
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