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After letting the TV I found dry out for a few days, I took it apart to have a look. At the very least it needed a new mains cable as that had been cut off.
It came apart quite easily, though there was one security screw to thwart poorly prepared tinkerers. But I’m not poorly prepared, and had the right security but to fit it.
I desoldered the stub of mains cable and soldered in a spare one. I usually cut mains cables off things I throw away, with their moulded mains plugs they’re often handy. I have an old ottoman that my grandfather made, full of scraps of useful wire & cables.
I plugged the TV into an extension lead, shut the door and switched it on from another room. Just in case it went bang.
The TV powered up, and I could select the menu and the built-in DVD player, which gives a garish built-in picture. But the colours look strange, and the screen slowly wobbles gently from side to side.
When set to a plain blue screen, the problem is clear. A large purple splodge, and strange colour on the bottom edge too.
On a CRT television, this is usually caused by the shadow mask in the tube getting magnetised. To defeat this, CRT TVs degauss themselves when you switch them on – the distinctive humm or thunk noise you used to hear. I switched this TV on and off a few times. I didn’t hear the noise, and testing with a compass showed no needle deflection. The degauss wasn’t working.
I looked at the circuitry in the TV connected to the degauss coil that runs around the tube. There’s not much to it. I noticed a 400 volt capacitor that was leaning over. Maybe it was damaged? The top was bulging. Aha! I unsoldered one of its two legs, and the capacitor fell out. The other leg had blown out of the capacitor at some time in the past.
I found some new ones on eBay at £3 for two including postage, so ordered those.
While I waited for the parts to arrive, I cleaned the TV a bit. The back of the case got a soak and a rinse in the shower, but the main unit had to be carefully cleaned by hand. As well as being grotty, it smelt if tobacco smoke.
The Febreeze freshener was a bit sickly smelling, but after a few days that faded and the cigarette smell had also gone.
New capacitor arrived, so I fitted that and tried the TV out. The screen remained splotchy.
Reading online, the tool I needed was a degauss coil. I don’t have one of those. They’re not cheap to buy, and how often am I going to use it in the future? So what else could I use?
I tried waving a strong magnet near the screen, which made pleasing blobs appear and disappear on the screen, but didn’t remove the original splotchy colours.
I don’t have a degaussing coil, but I do have a tape head demagnetiser tool. Tape heads get magnetised over time when playing cassettes, which causes a muffled playback sound. Demagnetising will fix that.
Maybe I could use that tool, and wave it around near the screen?
Waving the demagnetiser around caused instant splotches to appear and disappear, bit also after repeated tries, the original splotchy was getting smaller.
I continued this until the screen colour was very nearly perfect.
I adjusted the settings, reassembled the case and played a dvd.
It works! The built in DVD player is a little noisy, but I’m unlikely to use it. I’m not intending to watch TV on it, and can’t anyway without a digibox, as the TV only has an analogue TV tuner.
But what I do want it for is this
My first computer, from 1982. A Sinclair ZX81. It plugs into a TV, has no sound, is black and white output, and has a strange “keyboard”. I learnt to program on this!
But the repairs if that are for another blog post…