I just remembered when I was a kid(Im on my 30’s now) we had this old “box style” television. As it got older, there were times that a white thing will appear on the screen. You can still watch the show but its annoying. Imagine watching your TV while having a white curtain in front of it. One day, I got extremely furious because I was watching Smackdown and slap the side of the TV. Then, it returned to normal. I kept doing the same solution I discovered every time the white thing appears on screen until one day it stopped functioning. 😂
In: Technology
Dry solder joints. On old TV’s sometimes components worked loose from age and heat. Bashing the sweet spot jiggled the part back into place.
It was common enough in older electronics that the official fix for an early Apple PC was to drop it from a height of two inches
There are a lot of mechanical parts inside a TV including a magnet-guided electron gun that is shooting a beam through a metal screen with holes to align with at very specific red, green, and blue glowing bits on the glass. There’s a lot of potential for things to get misaligned, it’s possible that slapping it realigns them.
Probably mechanical defects in the set. Most likely cold solder joints or a connector that had a bad connection over time. In rare cases, the old tube tv sockets got loose, and the “thwack” remade the electrical connection.
Older Sony tv circuit boards were famous for having cold solder joints from the factory. I used to reheat every solder joint, especially the larger connectors and components, and 80% of the time, that fixed the problem.
There are multiple possibilities depending on what exact was wrong with the TV, but the two most common are these:
Loose connections, sometimes as wires or connections came loose or degraded, slapping it was enough to Jostle them back into the right place and fix the connection.
Or things being seated incorrectly or aligned incorrectly. Old school TVs required all the components to be aligned so the correct pixels got activated. If anything wasn’t aligned correctly it would mess up the display because the wrong pixels would get activated. Smacking it could make things bounce back into their correct place.
If you go way back, TVs had tubes. Tubes were eventually replaced by transistors. Most of the tubes fit into a socket soldered into the main board of the TV. After a while the connectors in these sockets would tarnish, which could cause unpredictable behavior in the TV. A good jolt would reseat the tubes in the sockets and things would start working again.
Slapping your tv didn’t fix it – it just jiggled the broken parts enough for them to temporarily make contact again and get a bit more functional time from it.
It could be a loose solder connection but probably not. More than likely, it was a corroded connector. Metal/metal contact with electric current is subject to fretting corrosion. Fretting is where tiny current paths move around on a microscopic scale giving corrosion a chance to disconnect them. A lot of engineering time and materials go into connector design to combat fretting but they still occasionally fail. Your consumer TV probably did not use the most expensive, gold plated beryllium copper high force, connectors. A little vibration is all it takes to restore connection.
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Old technician here:
One thing in particular causes this.
In old CRT tv sets there was a big heavy transformer that created high voltage. It would work at a quite high frequency. It’s this voltage that pulls beam of light put to the sides and up/down.
A TV image is drawn by a beam of light scrolling down over every line. Later on it was drawing every other line then doing it again to create the whole image.
A bit like we do it on modern screens too.
So this high voltage transformer would due to the high frequency sort of shake itself slightly loose.
You could at times hear the coils whine back then.
This could end up with connections in the coils getting loose and your image would either be a line or a dot at the center of the screen.
Giving it a good whack would jolt the connections in place making the image work.
A fix for this would be to take hair spray ( grandma’s big smelly cannister of hair spray) ans give it a good spray at the transformer. This would glue it in place for a while. Often years.
My printer is fixed by a similar method. It starts to make a terrible noise when printing which is rectified by a hard slap on the side. Took me back to the old TV days.
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