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EEVblog 1388 - Dumpster Diving TV Murphy's "Repair"

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EEVblog:
Dave fixed this Hitachi dumpster diving 4K TV so well that he broke it!

fable:
Here is schematic

eblc1388:
Should have used a wired 5A fuse for replacement. PFC switching MOSFET draws high instantaneous current through the inductor following the AC wave profile. This might have caused the PTC resettable fuse to go into higher than normal resistance, and PFC controller IC doesn't like it a bit.

BrianHG:
Ohh, the modern version of when in the old days, I would have a good working CRT, with an intermittent problem which occasionally required me to whack the display to fix.  I open it up, find a few cold solder joints.  I re-solder cleaning them up.  The display works for a day, then literally blows up the next time I power-on.

I was told by an experienced repair tech that some of TVs become dependent on the cold/poor contact solder joint and doing repairs may destroy the display.

ivb:

--- Quote from: BrianHG on April 24, 2021, 06:53:06 pm ---Ohh, the modern version of when in the old days, I would have a good working CRT, with an intermittent problem which occasionally required me to whack the display to fix.

--- End quote ---

I'm reminded of a similar problem my family had when I was growing up. Something went goofy in the tuner section of our CRT TV where it would just suddenly go out of tune despite being "digitally" tuned. My dad being a machinist and definitely not an EE or even electrician decided the best remedy was to drill a hole in the case directly above the RF shielded tuner and use a brass rod inserted to regularly hit the RF shield it until it came back in tune. We called it the "bonger" as in "get the bonger the TV's gone out again". Oddly enough no one ever managed to electrocute themselves despite what I now realize were our best efforts :palm:.

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