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Old 19th Dec 2018, 5:03 am   #47
Catkins
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Join Date: Feb 2015
Location: Chepstow, Monmouthshire, UK.
Posts: 234
Default Re: 1938 Murphy A56V television restoration

A couple of people have asked for the photos taken during the restoration. As I took hundreds, I'm happy to oblige showing the restoration each stage from start to finish. Obviously I can only show a few due to the 5 photograph limit, and so I'll choose what I think are the more interesting ones at each stage. But if you think I'm going too slowly, please mention it,

With the PSU finished I moved onto the main chassis. The next couple of months was spent stripping it down of components that needed restoring. Due to the generally rusted condition of the set, this was a slow process. A lot of the stuff wouldn't budge, and I don't like going to drastic measures unnecessarily, so a lot of soaking was necessary.

What needed to be removed? Obviously the electrolytics and the waxies. None of these on testing showed to be any good.

But, there was most of the top of the chassis, the transformers (audio, frame and line), the deflection coils, the mount (on top of the chassis) on which the CRT sits, the mount (on the bottom of the chassis) which holds the focus coil, and the CRT clamp. The wirewound trimmers needed to be removed because they were open circuit.

These all needed work on them.

Photo 1 shows a view of the bottom of the chassis, when I got the television. I realised I'd not shown a picture of that.

Photo 2 shows the removed "bottom CRT mount". This has a clamp, and it also has three brass knobs on threaded bolts, with springs, these adjust the focus coil (unseen as it on the other side). Both of these were rusted solid, and would subsequently need a lot of soaking to free up (if you're wondering how brass can rust, it obviously doesn't, it was the bolts that were rusted so they wouldn't move).

Photo 3 shows a close view of the frame transformer and deflection coils just before removal. This not only shows their generally rusted state, but, it also shows the state of the wiring. If you look closely at the wiring on the frame transformer, you should notice it is covered in white spots. At first I assumed this was mould, but mould is easy to brush off, and this wasn't. It is hard and won't easily break off. So where did it come from? Breaking the cotton covering and all becomes clear. Beneath the cotton covering was probably a layer of white rubber, this rubber has perished and it has left white dust which pours out on breaking. The white spots is presumably where it has sweated through the cotton in the damp conditions, leaving a dried hard white deposit.

The frame transformer will need to be completely stripped down due to its rusted state (along with the unshown audio output transformer in a similar state).

Photo 4 shows the removed deflection coils. If you look at this previously posted photo (https://www.vintage-radio.net/forum/...0&d=1544678770), you should be able to see the deflection coils are attached to the chassis via two sprung steel strips. Due to the fact the adjustment had rusted solid, at some previous date the sprung steel had been badly bent when the CRT had been inserted (due to being out of adjustment, and immovable). This has resulted in one of the steel strips breaking due to undue pressure.

The deflection coils will need to be stripped down to fix this, and the generally rusted state.

Photo 5 shows the removal of one of the wire-wound trimmers. The screws being rusted and soft, despite soaking, rounded off, requiring them to be drilled out. The photo also shows the generally grimy state of the under-chassis tag boards.
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