[Catkins]

Apologies for the two week delay in updates, I have been very busy in work, and this has left no time for anything else. As it is, it is now very late, and so I'm going to have to be very quick in this posting.

The last posting left me explaining all the things planned for my 2 week vacation over Christmas 2016 (and yes there's still almost two extra years of work still to detail).

As planned, I got the respraying of the top of the chassis done over late November and early December, leaving the paint work hard enough to start work on the underneath of of the chassis.

I had already had a good look at the paintwork underneath the chassis and decided it didn't need respraying, this was a very good bonus as it meant I didn't have to strip off all the components/tag-boards on the underside just for respraying, and it left them in place for the careful task of rewiring and component replacement (of the various restuffed waxies, electrolytics, and other repaired or replaced components).

There is a good reason why I wanted to keep the underside electronics in as undisturbed and original condition as possible. I didn't want to introduce issues/instability in the circuits. Pre-war televisions are notorious for pushing the available electronics to the limits due to the then high frequencies employed, and this often involved careful placement of components, wire routing and wire lengths. If you ever see something "unusual" in the placement or routing, this is usually the reason why, and you'd be stupid to loose this in any disassembly/reassembly and rewiring.

Photo 1 shows an obvious example of this, the frequency changer circuit. The entire frequency changer circuit is built on-top of the oscillator coil, and the whole assembly is immediately over the frequency changer valve socket. This makes an extremely dense and difficult to work with circuit, but, the obvious intent is to make the signal paths (wire-length etc) as short as possible. This is the reassembled and replaced circuit and pains were taken to match it exactly against photos taken before removal and disassembly. I replaced the connecting wires even though I knew I would eventually replace them, but, it is better to get everything right when replacing, and then follow that as a guide when replacing the wires, as it is less to concentrate on at that time.

My replacement of components and rewiring was pragmatic. I generally took one circuit at a time, and replaced components and rewired in "one go" to minimise the overall level of disruption. Rewiring was done one wire at a time, point to point, keeping each new wire the same length and preserving the routing. The components were replaced exactly using photographs.

The one exception to this was inter-circuit wiring, which I preferred to do separately, either before or after individual circuit rewiring, depending on circumstance. This is obviously because they relied on a global perspective to get the rewiring right. This mostly meant the filament wiring and the various HT feeds.

The filament wiring in the set was quite interesting. There are three separate circuits, with each one obviously connected to the same pins (on the power unit socket). The first circuit powers the valves on the lower side of the chassis (framebase, sync separator, and video detector/amplifier), the second circuit runs up the side powering the video IF valves, FC valve and HF valve. The third circuit powers the valves on the top side of the chassis, which are the linebase and the audio circuit valves. Additionally each circuit is wired the opposite way for negative and positive. The negative is daisy chained from one end of the circuit to the other end, and the positive is daisy chained from the other end. This I found quite unusual, and I can only assume it is an attempt to reduce inter-circuit interference.

There are separate three HT feeds in the circuit, and I again took pains to preserve the exact wiring between circuits. There were not many surprises here, but some circuits are daisy chained, and others are fed from a central HT point.

Photo 2 is a photo of the top left hand corner of the chassis in the middle of rewiring, with the waxies replaced. This shows the HF, Audio IF and Audio detector stages.

Photo 3 shows some rewired aerial/IF coils and Photo 4 shows one of them before rewiring.

One thing which perhaps needs to be mentioned here is the replacement wire. For this set I wanted to use wire that preserved the original vintage appearance. The cotton wire in the set was very dirty and very faded, but, one thing which was clear was that it was two-tone striped, with a darker colour and a lighter colour. This seems to me to be a particularly 1930s style, as I've never seen it in post war sets (but as usual there's always a first time which disproves this).

I looked for a long time for someone selling vintage NOS striped wire, and after a couple of months I finally found someone who had come across about 10 or so unused reels of different coloured striped wire. This wire was made in the early 1950s to a vintage colour coding. This was offered by the metre and it is easily the most expensive wire I have ever bought. But, I think it was worth it to preserve the original appearance.

Photo 5 is a view of the top of the resprayed chassis, showing the replaced coils and cans. At this point the rewiring was complete (except for the controls on long looms of wire, which would come much later).

Finally it looked to me, as if this might one day be a functioning TV again, rather than a lost hope.

But I'm out of time. This is mostly a pure brain dump due to lack of time, and I don't have time to edit it. As Pascal famously said, I would have written a shorter letter, but I did not have the time.