[Ghostuser]

I now have a complete V4 and VT4 and a scrap VT4! Some CRT swapping proved that both the VT4 and the scrap VT4 had much better CRTs than the original V4 and I have hopes of ending up with both a good V4 and a good VT4.
I have changed lots more waxies and moldseals and have the VT4 working quite well. Width was about an inch low, but I found that the line linearity adjustment did nothing. I swapped the linearity coil for one from the scrap chassis and got the width up to size, but only with the width control at max. Width still reduces as the set warms up.
The linearity coil lives near the booster diode and all three of mine look fried. I am having one re-wound, but wonder if anybody can comment on the durability of these coils?
Also, on the V4, I notice that there is a crack in the ferrite core of the LOPT. Is this a serious issue or is a small air gap acceptable?

BTW, The Aurora puts out a beefy RF signal. With a good set of EF80s in the RF section, the V4 worked fine. I then swapped some valves and lost contrast. To cut a long story short, I found that somebody had chopped out the cathode resistor of the RF stage. (They had also chopped off the components on the CRT base connector and a resistor from the HT supply, but I had found those) The Aurora clearly had given enough signal to couple to the second RF stage by stray capacitance until I put in some poorer EF80s!!

Ain't trouble shooting fun?

Cheers
Nigel