3 ms·

The author does mention unplugging it before starting a repair. I think the mains voltage isn't the issue unless you are feeling really down about the device br

The author does mention unplugging it before starting a repair. I think the mains voltage isn't the issue unless you are feeling really down about the device breaking, so down in fact that you would leave it plugged in before commencing work. Or do I not understand some fundamental of electronics repair that has high voltage on a unplugged device? (genuine question, not an electronics repair shop employee)

probably_wrong 11y ago
IIRC, TVs and similar devices store energy for certain components, so touching one of those can be lethal even if the device is unplugged.
Fradow 11y ago
Not a pro either, but I guess the risk, for an unplugged device, is about capacitor: they store current, and if you touch both ends of big one close to the alimentation, you are going to have a nasty shock. I had first hand experience of that: I repaired a screen, plugged it in to check it, then unplugged it and realized I forgot to cut the ends of a capacitor. When I touched it with a metal tool (luckily, the tool was insolated), there was some serious spark, that I guessed where due to capacitor discharge. Had I used my hand, this would have gone through my skin instead.
dagw 11y ago
Some device use high power capacitors to temporarily store electrical energy and these can remain charged long after the plug is pulled.
rahimnathwani 11y ago
You could also accidentally connect a live wire to the metal housing, causing the entire outside of the device to become live when you plug it in after the repair.
- jschwartzi 11y ago
  Or accidentally cut yourself on the housing or tools, for that matter.
- PeterisP 11y ago
  That should not be an option - the device should (and IIRC is required to) be designed with a grounded housing, so if you do actually accidentally connect a live wire, then it would just blow a fuse by that short circuit.
  - rahimnathwani 11y ago
    True. So I'd have to make at least two mistakes: let a live wire make contact with the case, and disconnect the ground connection to the case.

probably_wrong 11y ago

IIRC, TVs and similar devices store energy for certain components, so touching one of those can be lethal even if the device is unplugged.

Fradow 11y ago

Not a pro either, but I guess the risk, for an unplugged device, is about capacitor: they store current, and if you touch both ends of big one close to the alimentation, you are going to have a nasty shock. I had first hand experience of that: I repaired a screen, plugged it in to check it, then unplugged it and realized I forgot to cut the ends of a capacitor. When I touched it with a metal tool (luckily, the tool was insolated), there was some serious spark, that I guessed where due to capacitor discharge. Had I used my hand, this would have gone through my skin instead.

dagw 11y ago

Some device use high power capacitors to temporarily store electrical energy and these can remain charged long after the plug is pulled.

rahimnathwani 11y ago

You could also accidentally connect a live wire to the metal housing, causing the entire outside of the device to become live when you plug it in after the repair.

jschwartzi 11y ago
Or accidentally cut yourself on the housing or tools, for that matter.
PeterisP 11y ago
That should not be an option - the device should (and IIRC is required to) be designed with a grounded housing, so if you do actually accidentally connect a live wire, then it would just blow a fuse by that short circuit.
- rahimnathwani 11y ago
  True. So I'd have to make at least two mistakes: let a live wire make contact with the case, and disconnect the ground connection to the case.