Fun fixing my own TV

I recently thought about some of the things I did when I was young and wondered how I have not received permanent injuries from some of the things I did. Perhaps I have. It’s not that I was particularly wild, but as I child I didn’t take too much notice of safety – I guess I thought I was indestructible.

I planned to write about some of the dangerous things I did but when I started putting them all together I risked looking like a complete twit if put it in all one article, so I’ve decided to just mention one incident. Maybe I’ll mention some others later.

When I was in High School I loved to fiddle with electronics. I wanted a TV in my bedroom but I certainly couldn’t afford a new one. Colour TVs had only been available in Australia for six or seven years so old colour ones were not easily available either. My Mum managed to get a broken black and white valve set (or tubes as that is what I believe they are called in some parts) and a few old chassis. The TV was in a large wooden cabinet with the speaker at the bottom a bit like this one. It didn’t need a stand – it was big, or at least the box was. The screen wasn’t particularly big.

I regularly read “The Serviceman” articles in electronics magazines. This probably sounds quite dull, but you may be quite surprised if you read them. Like all good writing, pleasure gained is more to do with the writing style than the subject and these articles where often quite funny detailing interesting customer interactions as well as how tricky technical problems were solved.

Using information I learned from these I began swapping components from the broken set with bits in the other chassis I had from areas of the TV where I suspected the problem was. Basically just using trial and error although one great feature that it had like many electrical things of that time was  a schematic diagram stuck on the inside of the cabinet which helped. I eventually suspected the high voltage flyback transformer that ran the picture tube. These things apparently put out around 15 000 to 20 000 volts and need lots of care when they are running. I found a similar one in a chassis and swapped it. The TV I was fixing had a metal guard covering the transformer and a valve that a big metal connector on top with a wire that ran to the transformer. I couldn’t get the top of the guard back on, so I just left it off – after all most of the other chassis I had didn’t even have one. Switching the TV on brought it to life. Placing the tip of a screwdriver near the connector on the valve that ran to the transformer would produce a nice constant spark about 1cm long. I was pretty pleased with myself, even though I had used trial an error more than proper diagnosis. The first lesson I learned is fixing things is very rewarding.

I used the TV for quite a while and I even remember watching the Poseidon Adventure on it. One day I decided to adjust the horizontal hold while I had the back off the set. I reached around the back to adjust the knob while watching the screen to see what difference I was making. It was then I touched the metal connector on top of the valve. I got one hell of a whack. In some things I’ve read they have said that these are not that dangerous because even though it is high voltage the current is low and someone even said that when he did it he didn’t even notice except for the burning smell. That was not my experience – I felt pain and was left with tingling in my arm for the next half an hour. The second lesson I learned was respect electricity, because it won’t respect you.

It was about that time that we got a special protection gadget wired into our fuse box.

If you want to see what these transformers can do just go to YouTube and do a search for flyback transformer.

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Posted on October 13, 2012, in Electronics and tagged , , , , , , , . Bookmark the permalink. Comments Off on Fun fixing my own TV.

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