In article , Don Pearce
wrote:
On Sun, 03 Aug 2014 16:37:01 +0000 (GMT), Jim Lesurf
wrote:


FWIW When I used to install and use systems on the old UKIRT
(Telescope) they were always 'grounded'. But always gave you a multi-kV
static shock if you were the first to touch them after they'd been left
un-touched for about 10 mins or more. The ground connection was
essentially dry rock in a dry atmosphere. So was little more than a
common reference. Certainly not a way of ensuring no overall charge
potential. 8-]

What do you reckon was the capacitance to true ground? More than a
couple of hundred pF and you can start to feel it properly.

No idea of the capacitance. It gave a nice spark so the potential was high.
And the discharge was enough to cause pain. The telescope was essentially a
metal cage about 2-3 metres in diameter and maybe 8 metres long. With a lot
of kit hanging from the back. I'm not sure where the charge was leaking
from. But the prime suspect was either the 2kV dc PSU when using a klystron
or the 8kV one when using a carcinotron.

In practice I suspect what controlled the discharge was the electrostatic
capacitance of the human as the charge densities on the telescope and the
person came to equilibrium. The floor was usually also dry. So someone else
being 'first' didn't guarantee that the next person wouldn't get a tingle.

Once experienced you either used something resistive to make 'first
contact' or used the ploy that firemen are taught. First touch with the
*back* of your hand so the stimulated reflex is to jerk away.

Jim

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In article ,
Phil Allison wrote:
** It backs up my point it cos the miswired Bulgin lead would have
worked and not been a serious hazard until it arrived at BBC TV and got
plugged one of their iso trannies.

Then you might care to explain why there was not once case of electrical
shock or whatever under those circumstances. But many incidents and even
deaths where bands were 'on the road' with not an isolating transformer in
sight.

I do realise logic isn't your strong point, though.

--
*Artificial Intelligence is no match for Natural Stupidity *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Phil Allison wrote:
** Nothing civilised about the how you pommy ****s grossly over-snip and
then reply in another context.

The original context was set in the PAST when mains leads used with
BRITISH made guitar amps often looked like the one in this link.

http://forums.vintageamps.com/viewtopic.php?p=489386

Either ends can be wired wrongly, the Bulgin end being the more likely.

Since I started this topic you've taken over with your usual insults -
while failing to help in any way with the original question - I'd point
out that the 405 is fitted with an IEC mains inlet. And pretty well all
IEC leads come with that connector moulded on. The small mains Bulgin used
on the 303 and 33 is a solder connector - so unlikely to be mis-wired
other than by a total idiot. (It may be that small Bulgin was also used in
early versions of the 405)

You'd have to go back two generations of Quad to the valve amps to find
that particular Bulgin connector in use.

--
*Young at heart -- slightly older in other places

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman Criminal Psychopath"


Since I started this topic you've taken over with your usual insults -
while failing to help in any way with the original question - I'd point
out that the 405 is fitted with an IEC mains inlet.

** Yawnnnnnnnnnnnn..............


And pretty well all
IEC leads come with that connector moulded on.

** Shame how Quad supplied a re-wirable IEC plug packed with each 405.

Cos there are so many different, ****ing AC plugs on the planet.


The small mains Bulgin used
on the 303 and 33 is a solder connector - so unlikely to be mis-wired

** Fraid that makes it maximally likely to be miswired.

You cock sucking pommy ****.


(It may be that small Bulgin was also used in early versions of the 405)

** Whaaaaatttttt ?

FFS - you are one raving, psycho, pommy lunatic ****.


You'd have to go back two generations of Quad to the valve amps to find
that particular Bulgin connector in use.

** The Quad ESL used an earlier and larger Bulgin AC connector.

As did Marshalls, Oranges and Sound City amps et alia.

God I hope you have a massive stroke, ASAP




..... Phil