[ALUG] R31 Locks when removing adapter

Simon Ransome simon at nosher.net
Thu Jan 13 09:31:17 GMT 2011


Wayne Stallwood wrote:
> Now if we were talking about CRT TV's which I made the assumption hardly
> anyone is still using...then yes it was very common for them not to have
> a earth connection because the nature of the most common method of
> powering the things (i.e shoving mains through a bridge rectifier which
> has it's negative side tied to Chassis) means that the chassis can sit
> at what looks roughly on most meters like half mains potential. In fact
> it is more like half wave AC at roughly -320volts. This is why if you
> are particularly well grounded you will feel a bite from the antenna
> socket of many CRT TV sets

Aaaaah! Thanks for describing this, it's answered a long-standing puzzle
filed away in the "back in the day" section of my brain. I had several
shocks from the antenna socket of various CRT TVs, and having
experienced mains shocks could tell that it wasn't static and that it
did indeed feel like mains AC, but was always puzzled why this should be
the case when the UHF socket in question was a) a supposedly un-powered
inbound connection and b) something designed for a few microvolts @ a
few hundred MHz. Know I know :-)

Cheers,
Simon


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