On 24/07/14 19:39, whit3rd wrote:
On Thursday, July 24, 2014 10:02:01 AM UTC-7, aeio wrote:
I noticed a tingling from contact with a USB lead of an external Hard Drive.


Investigating this led to the PSU, the plug of which has a high voltage
on the outer connector compared with house earth. It was varying between
70 and 110V.

A voltmeter might pick up leakage, but to determine if it's hazardous, you
need a load. I'd start with AC milliamp scale (try on high amp scale first, of course)
to test further. It's probably a bad PSU just as you suspect (if you feel it
it's maybe a few milliamps, but microamps might be acceptable).
Connect one probe to ground, the other to the touchable metal part.

The 'correct' way to test involves a dive into a variety of national and
international standards. One half milliamp into 1500 ohms parallel with
0.15 uF, is a typical 'safe' threshold.

slowly going up and down between 0 and .005 milliamps - on a cheap
multimeter.

Is it worth trying it with a capacitor?