Author Topic: Be careful with those teardowns, kids!  (Read 20555 times)

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Offline nukie

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Re: Be careful with those teardowns, kids!
« Reply #75 on: October 12, 2012, 01:50:39 pm »
It's really sad to have such cases happening, then the regulators would make stupid laws and the DIY would be in difficult times.

If it was me, I probably be on the news for at least 7 times. I am not boasting I cannot be killed by electricity but as a matter of fact my brain cells are probably half fried. I haven't been zapped for many years due to extra care, but the last time was a few weeks ago. I was fixing a Samsung LCD TV surprise surprise it's not due to bad cap. I took all the precaution, bleeding off the main cap as it was 330uf 400v. I did it over and over again as I try to diagnose the problem. Then due to fatigue I reach out to feel the heatsink if the diodes are heating up... That was the most painful zap I ever experienced. The pain lasted for at least 5 minutes my whole arm felt sore perhaps due to muscle reaction. That was as close experience as commit suicide, it really scared me properly.

When I was young I was mains electricity curious. I trip the fuse often, as a result my butt always get rewarded with a cane. I hate christmas lights, they give varying intensity of electrocution. The closer you are to the plug the stronger the zap. Once when I was a kid, I stood on a table to plug in my NiCD charger, I got zapped and it threw me off the table and I was lucky I landed on my butt not my head. But I was unconscious for a few seconds luckily there was no one around to administrator the cane. I learned to keep my tiny fingers away from those unshielded pins. Nowadays it's kids friendly they are shielded pins on the mains plug.

When I was a teenager, I manage to get a job in a TV repair shop. There I learned a lot from the seniors regarding mains safety. Of the 3 years I worked there as a part time apprentice, never once I saw someone got zapped.

This kid misfortune probably due to his weaker heart. I have seen a lot of cheap power supply but most of them have cheap input caps and they have quite high leakage so they self discharge quickly. You can measure the voltage drop as soon as it is unplugged. He's probably operating a name brand supply with a good input cap but without a bleeder resistor? I don't think he's stupid, he's just as curious as everyone here. If he was trained and killed then he is stupid and unlucky.
« Last Edit: October 12, 2012, 01:55:07 pm by nukie »
 

Offline SeanB

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Re: Be careful with those teardowns, kids!
« Reply #76 on: October 12, 2012, 03:30:00 pm »
A big CRt can have an anode capacitance of quite a few nanofarads, which is pretty high energy when charged to 30kV.
 

Offline G7PSK

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Re: Be careful with those teardowns, kids!
« Reply #77 on: October 12, 2012, 04:04:04 pm »
I have just found this, which is very useful information on electric shock, it would apear that under certain conditions a higher current is more survivable than lower current.

http://www.physics.ohio-state.edu/~p616/safety/fatal_current.html



 


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