While working on TV I got all the usual shocks. The worst one on B&W
TV was HT on a Rediffusion set. EHT was a much higher voltage but very
low current. I never got a EHT shock from the very early colour sets I
worked on with DER. I saw one of the other engineers get a shock from
a colour TV EHT supply. It floored him. I had a tube discharge
occasionally from new tubes (still boxed) arriving from the supplier.
I always held on to the tube but swore at Mullard. Years later I
started working on computer peripherals. I got a shock from an Ampex
spooler motor servo when it decided to spool in the magnetic tape.
That was a very bad shock and I had to have a lie down for a while.
Everybody laughed!

In article <gghpdids1qal9vg3g20b92vbeah9mr01ac@4ax.com>, Stephen
Wolstenholme <stephenwolstenholme30@outlook.com> scribeth thus
>While working on TV I got all the usual shocks. The worst one on B&W
>TV was HT on a Rediffusion set. EHT was a much higher voltage but very
>low current. I never got a EHT shock from the very early colour sets I
>worked on with DER. I saw one of the other engineers get a shock from
>a colour TV EHT supply. It floored him. I had a tube discharge
>occasionally from new tubes (still boxed) arriving from the supplier.
>I always held on to the tube but swore at Mullard. Years later I
>started working on computer peripherals. I got a shock from an Ampex
>spooler motor servo when it decided to spool in the magnetic tape.
>That was a very bad shock and I had to have a lie down for a while.
>Everybody laughed!
>

Many years ago around 1977 "ish" i had to help the aerial rigger out in
a TV shoppe where i worked at that time.

This old chap was bedridden so his relatives thought a TV in his bedroom
would be a great idea so aerial rigged and cable was to come in thru a
metal window frame so i had the drill in hand and to do this had to
reach out of the window and move the ladder sideways a bit.

Drill was a metal cased one, ladder was in soft damp earth as it was
raining a lot at that time and yes you can guess what happened next the
moment my hand went around the ladder i was being very badly and very
painfully shocked so much so i couldn't move anything couldn't move
speak even just everything seems to be vibrating at 50 Hz inc me.

Fortunately the chap i was working with came into the room and saw what
was going on and put 2 and more together rapidly and unplugged the drill
and at that point i collapsed on the floor was taken to hospital and
told that if it had gone on any longer the heart would have possibly
stopped pumping so took a day off work and then back to work.

The reason what it happened was that the house was still wired in the
old type of Rubber mains cable that the earth had come undone at the
distribution board the man from the electric co thought it might have
never been connected on the upstairs ring main but matey had nothing in
his room to be earthed to as such so had been living like that for many
years a thick carpet was possibly a good insulator!

So the arsehole who ran the firm saw this as a bit of a joke and said
that in the past he had to kick the odd drill out of his hand and i
covered the handle of d said drill with insulating tape which he told me
to man up and take it off, i then lost my rag with him and told him
either i leave the tape on or stick the 'effing drill up his arse and he
didn't back down so i did just that lucky for he it wasn't turning i
then helped myself to a months pay and told him to go fuck himself.

The aerial rigger came out in sympathy and so did the other engineer
owing to his attitude he died around a couple of years later and the
bloody building burnt down owing to duff wiring!

As to EHT shocks yep a few colour Tubes were dropped owing the charge
rebuilding on CRTs made a bloody mess being b dropped on the works
floor!

--
Tony Sayer

Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

On 16/08/2023 15:52, tony sayer wrote:
> As to EHT shocks yep a few colour Tubes were dropped owing the charge
> rebuilding on CRTs made a bloody mess being b dropped on the works floor!

Many says that RF burns are the worse and tend not to heal up.

I once disconnected a feeder with a few KW or RF on it (I had been
assured it was turned off). It was very impressive, I heard a 'clunk'
from the other end of the building as the amplifier tripped off but no
arcing or burning.

On Wed, 16 Aug 2023 16:37:01 +0100, MB wrote:

> Many says that RF burns are the worse and tend not to heal up.

When I was working on flight simulators (between TV jobs) they were using
genuine aircraft components and 400Hz power and I accidentally brushed a
finger against a live 400Hz terminal and it burnt a small hole in the skin
but it didn't need to heal because it cooked it!

--
TOJ.

On 16/08/2023 19:34, The Other John wrote:
> On Wed, 16 Aug 2023 16:37:01 +0100, MB wrote:
>
>> Many says that RF burns are the worse and tend not to heal up.
>
> When I was working on flight simulators (between TV jobs) they were using
> genuine aircraft components and 400Hz power and I accidentally brushed a
> finger against a live 400Hz terminal and it burnt a small hole in the skin
> but it didn't need to heal because it cooked it!

I've had a few mains shocks - the most stupid was the other year when I
was changing some light fittings which had Philips Hue bulbs in them.
These tend to be left permanently powered on, and the individual bulbs
on a circuit are turned on/off/dimmed by app. Each time I did a batch of
fittings, I turned off both the wall switch and the lighting circuit at
the "fuse box". After a break I did some more. And I made the elementary
mistake of thinking "the lights are not lit, so the circuit must be off
at the wall". As my screwdriver touched the live screw on the terminal
block I must have had contact with the screwdriver and also with the
neutral. It's the first time I've had a mains shock on a circuit with an
RCD, and the fact that it tripped meant that I didn't have to pull my
hand way to break the circuit.

Others in the past have been on a non-tripping circuit before the days
of RCDs - eg when I touched the terminals where the mains cable of a
tape recorder was soldered to the main power switch. The switch was
turned off, but the feed to it wasn't...

The worst was from that same tape recorder. It used valves, so it had an
HT feed which was higher than mains: I later measured the terminals that
I had touch as about 400 V AC (before the diodes and smoothing). That
F-ing hurt: my arm throbbed for several hours.

The most bizarre was when I was unplugging the TV aerial lead from a USB
TV tuner on my (earthed) computer. I had the metal screen of the aerial
in one hand and the other hand on the computer, and I got a very
noticeable tingle. I measured about 150 V between aerial screen and
mains earth, using a high-resistance voltmeter. I went round all my
electronic equipment that was connected together: aerial went to TV, VCR
and computer; TV, VCR, hifi were all connected by audio phono plugs. By
unplugging things in turn I eventually tracked it down to the TV: one
with a CRT. With nothing connected to it apart from the mains lead,
there was about 150 V between its aerial screen and/or aerial signal
pin, and mains earth. I measured my body resistance (about 300 k ohms)
and made up resistors to mimic this (I didn't fancy using my body again
for testing, the tingle was that bad) and measured about 50 V with a
simulated body between TV and mains earth. There was evidently a fairly
high safety resistor in series, but still enough current flowed though
the "test human body" to give a voltage that was very noticeable.

After that, I attached a wire between the aerial plug of the aerial amp
PSU and the mains earth pin for the amp's PSU, so the whole signal earth
for the TV/VCR/hifi/computer setup was earthed at that one point (didn't
want multiple earths in case of hum loops).

That's the problem with modern electronic equipment: live and neutral
but not earth, so if there *is* any leakage, and there is insufficient
safety resistance, you're going to feel it.

I suppose I was unlucky that when I touched that aerial plug initially,
I was also touching an earthed computer. Any other device would have had
two wires only so there would have been no voltage difference between
the 80 V on the aerial and something else.

Yes we always laugh at others misfortunes. The Mk10 sets did have a live
chassis of course. The colour ones also had x ray issues I can recall bush
and Murphy sets needing to have a screen put into the line output valve base
to stop irradiating the pets sleeping under the telly.
Yes all tubes could be charged up. Later on they used to come in with a
conductive device in the anode hole that earthed to the outside coating, but
nobody ever put them back in if they needed to change a tube that would not
converge, as we learned that quite often another set of pcbs and yolk would
allow it to work.
Tolerances and all that.
My most memorable shock was while working in regional repairs the old
tmebase pcbs had the mains switch on them, and plugged into an edge
connector on the test rig. Trouble was with age and hot valves they bowed,
and one had to push the middle down to line it up with the connector, but
if you forgot to turn the mains off, you often got a belt between two
fingers of one hand as it made contact. Buzz bloody expletive.
Brian

--

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Blind user, so no pictures please
Note this Signature is meaningless.!
"Stephen Wolstenholme" <stephenwolstenholme30@outlook.com> wrote in message
news:gghpdids1qal9vg3g20b92vbeah9mr01ac@4ax.com...
> While working on TV I got all the usual shocks. The worst one on B&W
> TV was HT on a Rediffusion set. EHT was a much higher voltage but very
> low current. I never got a EHT shock from the very early colour sets I
> worked on with DER. I saw one of the other engineers get a shock from
> a colour TV EHT supply. It floored him. I had a tube discharge
> occasionally from new tubes (still boxed) arriving from the supplier.
> I always held on to the tube but swore at Mullard. Years later I
> started working on computer peripherals. I got a shock from an Ampex
> spooler motor servo when it decided to spool in the magnetic tape.
> That was a very bad shock and I had to have a lie down for a while.
> Everybody laughed!
>

Yes, our house was wired like that as well. In the 70s we had it redone with
pvc. So its the old colours and basic circuit breakers but has served me
well since and I see no need to alter stuff.

The worst things to work in are static caravans, as bodgit and run seem to
have done most of the wiring and all of a sudden a metal piece will become
live.
Brian

--

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briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"tony sayer" <tony@bancom.co.uk> wrote in message
news:4w99S0AQKO3kFw3i@bancom.co.uk...
> In article <gghpdids1qal9vg3g20b92vbeah9mr01ac@4ax.com>, Stephen
> Wolstenholme <stephenwolstenholme30@outlook.com> scribeth thus
>>While working on TV I got all the usual shocks. The worst one on B&W
>>TV was HT on a Rediffusion set. EHT was a much higher voltage but very
>>low current. I never got a EHT shock from the very early colour sets I
>>worked on with DER. I saw one of the other engineers get a shock from
>>a colour TV EHT supply. It floored him. I had a tube discharge
>>occasionally from new tubes (still boxed) arriving from the supplier.
>>I always held on to the tube but swore at Mullard. Years later I
>>started working on computer peripherals. I got a shock from an Ampex
>>spooler motor servo when it decided to spool in the magnetic tape.
>>That was a very bad shock and I had to have a lie down for a while.
>>Everybody laughed!
>>
>
> Many years ago around 1977 "ish" i had to help the aerial rigger out in
> a TV shoppe where i worked at that time.
>
> This old chap was bedridden so his relatives thought a TV in his bedroom
> would be a great idea so aerial rigged and cable was to come in thru a
> metal window frame so i had the drill in hand and to do this had to
> reach out of the window and move the ladder sideways a bit.
>
> Drill was a metal cased one, ladder was in soft damp earth as it was
> raining a lot at that time and yes you can guess what happened next the
> moment my hand went around the ladder i was being very badly and very
> painfully shocked so much so i couldn't move anything couldn't move
> speak even just everything seems to be vibrating at 50 Hz inc me.
>
> Fortunately the chap i was working with came into the room and saw what
> was going on and put 2 and more together rapidly and unplugged the drill
> and at that point i collapsed on the floor was taken to hospital and
> told that if it had gone on any longer the heart would have possibly
> stopped pumping so took a day off work and then back to work.
>
> The reason what it happened was that the house was still wired in the
> old type of Rubber mains cable that the earth had come undone at the
> distribution board the man from the electric co thought it might have
> never been connected on the upstairs ring main but matey had nothing in
> his room to be earthed to as such so had been living like that for many
> years a thick carpet was possibly a good insulator!
>
> So the arsehole who ran the firm saw this as a bit of a joke and said
> that in the past he had to kick the odd drill out of his hand and i
> covered the handle of d said drill with insulating tape which he told me
> to man up and take it off, i then lost my rag with him and told him
> either i leave the tape on or stick the 'effing drill up his arse and he
> didn't back down so i did just that lucky for he it wasn't turning i
> then helped myself to a months pay and told him to go fuck himself.
>
> The aerial rigger came out in sympathy and so did the other engineer
> owing to his attitude he died around a couple of years later and the
> bloody building burnt down owing to duff wiring!
>
>
> As to EHT shocks yep a few colour Tubes were dropped owing the charge
> rebuilding on CRTs made a bloody mess being b dropped on the works
> floor!
>
> --
> Tony Sayer
>
>
> Man is least himself when he talks in his own person.
>
> Give him a keyboard, and he will reveal himself.
>
>

On a Lenovo laptop the case buzzes as you run a finger over it. The signal
is transferred from the mains unit, again no earth.
The TV you mention was probably one of the live chassis types, though some
were actually half mains voltage but it made little difference as you still
felt it even with a capacitor linked earth on the aerial socket.
The measured voltage at the time was 114v, but it was just a pulse.
Even the current Samsung flat screen TV has a measurable voltage on the
aerial if no other plugs are in, but since it has a video input for use as a
monitor, and some usp inputs, all going to an earthed computer, then there
is no further issue.
I guess a lot of this is electrostatic.
If you wear the wriite cloths and use the Henry cleaner in a room with a
nylon carpet, you get shocks at regular intervals due to the air over
plastic and the metal extension pipe making a good electrode to pick it up
of course.
Near me is a line of big pylons, and as I walk near them and hold out my
aluminium white cane, and run my finger along the exposed metal bits aI can
feel/hear the hum from the wires. There is a house almost under the wires in
one place and its changed hands many many times. Apparently people get
shocks inside it and it is always dusty in the house, one assumes the static
clumps the microscopic dust together giving the appearance of more than
usual dust.
It was built 10 feet too close to the wires apparently but was declared
safe.

Brian
--

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Note this Signature is meaningless.!
"NY" <me@privacy.net> wrote in message
news:Aq6dnYBJO7yOokD5nZ2dnZfqn_idnZ2d@brightview.co.uk...
> On 16/08/2023 19:34, The Other John wrote:
>> On Wed, 16 Aug 2023 16:37:01 +0100, MB wrote:
>>
>>> Many says that RF burns are the worse and tend not to heal up.
>>
>> When I was working on flight simulators (between TV jobs) they were using
>> genuine aircraft components and 400Hz power and I accidentally brushed a
>> finger against a live 400Hz terminal and it burnt a small hole in the
>> skin
>> but it didn't need to heal because it cooked it!
>
> I've had a few mains shocks - the most stupid was the other year when I
> was changing some light fittings which had Philips Hue bulbs in them.
> These tend to be left permanently powered on, and the individual bulbs on
> a circuit are turned on/off/dimmed by app. Each time I did a batch of
> fittings, I turned off both the wall switch and the lighting circuit at
> the "fuse box". After a break I did some more. And I made the elementary
> mistake of thinking "the lights are not lit, so the circuit must be off at
> the wall". As my screwdriver touched the live screw on the terminal block
> I must have had contact with the screwdriver and also with the neutral.
> It's the first time I've had a mains shock on a circuit with an RCD, and
> the fact that it tripped meant that I didn't have to pull my hand way to
> break the circuit.
>
> Others in the past have been on a non-tripping circuit before the days of
> RCDs - eg when I touched the terminals where the mains cable of a tape
> recorder was soldered to the main power switch. The switch was turned off,
> but the feed to it wasn't...
>
> The worst was from that same tape recorder. It used valves, so it had an
> HT feed which was higher than mains: I later measured the terminals that I
> had touch as about 400 V AC (before the diodes and smoothing). That F-ing
> hurt: my arm throbbed for several hours.
>
> The most bizarre was when I was unplugging the TV aerial lead from a USB
> TV tuner on my (earthed) computer. I had the metal screen of the aerial in
> one hand and the other hand on the computer, and I got a very noticeable
> tingle. I measured about 150 V between aerial screen and mains earth,
> using a high-resistance voltmeter. I went round all my electronic
> equipment that was connected together: aerial went to TV, VCR and
> computer; TV, VCR, hifi were all connected by audio phono plugs. By
> unplugging things in turn I eventually tracked it down to the TV: one with
> a CRT. With nothing connected to it apart from the mains lead, there was
> about 150 V between its aerial screen and/or aerial signal pin, and mains
> earth. I measured my body resistance (about 300 k ohms) and made up
> resistors to mimic this (I didn't fancy using my body again for testing,
> the tingle was that bad) and measured about 50 V with a simulated body
> between TV and mains earth. There was evidently a fairly high safety
> resistor in series, but still enough current flowed though the "test human
> body" to give a voltage that was very noticeable.
>
> After that, I attached a wire between the aerial plug of the aerial amp
> PSU and the mains earth pin for the amp's PSU, so the whole signal earth
> for the TV/VCR/hifi/computer setup was earthed at that one point (didn't
> want multiple earths in case of hum loops).
>
> That's the problem with modern electronic equipment: live and neutral but
> not earth, so if there *is* any leakage, and there is insufficient safety
> resistance, you're going to feel it.
>
> I suppose I was unlucky that when I touched that aerial plug initially, I
> was also touching an earthed computer. Any other device would have had two
> wires only so there would have been no voltage difference between the 80 V
> on the aerial and something else.

In message <ubkq3o$3nt7v$1@dont-email.me> at Thu, 17 Aug 2023 10:43:17,
Brian Gaff <brian1gaff@gmail.com> writes
[]
> Near me is a line of big pylons, and as I walk near them and hold out my
>aluminium white cane, and run my finger along the exposed metal bits aI can
>feel/hear the hum from the wires. There is a house almost under the wires in
>one place and its changed hands many many times. Apparently people get
>shocks inside it and it is always dusty in the house, one assumes the static
>clumps the microscopic dust together giving the appearance of more than
>usual dust.
> It was built 10 feet too close to the wires apparently but was declared
>safe.
>
>Brian

Presumably, if arranged properly, they can have free lighting, at night
at least, with judicious placement of fluorescent tubes.
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

Lewis: ... d'you think there's a god?
Morse: ... There are times when I wish to god there was one. (Inspector Morse.)

On 17/08/2023 10:43, Brian Gaff wrote:
> The TV you mention was probably one of the live chassis types, though some
> were actually half mains voltage but it made little difference as you still
> felt it even with a capacitor linked earth on the aerial socket.

I'd be surprised if a modern TV was live chassis. This was one of the
last CRT TVs to be sold: a widescreen Panasonic which I bought in 2000
when I moved to a bigger house and needed something larger than the 14"
TV that I'd bought in the late 80s.

I presume live chassis sets had problems because the one connection to
them, apart from the mains lead, was for the aerial. If the aerial
screen was as mains or half-mains voltage, I presume it could not be
earthed and had to have an insulating cover over the normally metal
Belling Lee plug. I remember some aerial leads where the plug was flat
rather than cylindrical, with a rubber/plastic cover over it.

On Wed, 16 Aug 2023 14:31:52 +0100, Stephen Wolstenholme
<stephenwolstenholme30@outlook.com> wrote:

>While working on TV I got all the usual shocks. The worst one on B&W
>TV was HT on a Rediffusion set. EHT was a much higher voltage but very
>low current. I never got a EHT shock from the very early colour sets I
>worked on with DER. I saw one of the other engineers get a shock from
>a colour TV EHT supply. It floored him. I had a tube discharge
>occasionally from new tubes (still boxed) arriving from the supplier.
>I always held on to the tube but swore at Mullard. Years later I
>started working on computer peripherals. I got a shock from an Ampex
>spooler motor servo when it decided to spool in the magnetic tape.
>That was a very bad shock and I had to have a lie down for a while.
>Everybody laughed!

I've just remembered another "classic" shock from my mainframe
computer days. Some sites had rooms full of ICL EDS80 for data
storage. Each EDS80 was connected to three phase but only used one
phases. Operators would sometimes take a short cut through the gap
between two EDS80 by leaning on both drives. Just occasionally
adjacent EDS were connected to different phases. Thank the lord that
the gray/orange cover paint was quite thick. See
https://commons.wikimedia.org/wiki/File:ICL_EDS80_at_Vintage_Computer_Festival_(1).jpg
It wasn't me but one of the operators. She was very unhappy. It took
me a while to convince her that I didn't do any of the power wiring.
We got the local electricity board engineers for that.

In message <pc6cnXyFXY0-k0P5nZ2dnZfqn_ednZ2d@brightview.co.uk> at Thu,
17 Aug 2023 13:12:17, NY <me@privacy.net> writes
[]
>I presume live chassis sets had problems because the one connection to
>them, apart from the mains lead, was for the aerial. If the aerial
>screen was as mains or half-mains voltage, I presume it could not be
>earthed and had to have an insulating cover over the normally metal
>Belling Lee plug. I remember some aerial leads where the plug was flat
>rather than cylindrical, with a rubber/plastic cover over it.

I think they just had a capacitor coupling between the aerial socket
outer and the internal "ground". A fairly tiny capacitance would suffice
for UHF, but not carry enough current to be harmful (at least, in the
days when electric razor chargers were considered safe with just a
capacitive dropper!).
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

As individuals, politicians are usually quite charming, so it is quite hard to
dislike them, but in most cases, it is worth making the effort.
- Mark Williams (UMRA), 2013-4-26

On Thu, 17 Aug 2023 14:56:16 +0100, steve1001908 wrote:

> On Wed, 16 Aug 2023 14:31:52 +0100, Stephen Wolstenholme
> <stephenwolstenholme30@outlook.com> wrote:
>
>>While working on TV I got all the usual shocks. The worst one on B&W TV
>>was HT on a Rediffusion set. EHT was a much higher voltage but very low
>>current. I never got a EHT shock from the very early colour sets I
>>worked on with DER. I saw one of the other engineers get a shock from a
>>colour TV EHT supply. It floored him. I had a tube discharge
>>occasionally from new tubes (still boxed) arriving from the supplier. I
>>always held on to the tube but swore at Mullard. Years later I started
>>working on computer peripherals. I got a shock from an Ampex spooler
>>motor servo when it decided to spool in the magnetic tape. That was a
>>very bad shock and I had to have a lie down for a while. Everybody
>>laughed!
>
> I've just remembered another "classic" shock from my mainframe computer
> days. Some sites had rooms full of ICL EDS80 for data storage. Each
> EDS80 was connected to three phase but only used one phases. Operators
> would sometimes take a short cut through the gap between two EDS80 by
> leaning on both drives. Just occasionally adjacent EDS were connected to
> different phases. Thank the lord that the gray/orange cover paint was
> quite thick. See
> https://commons.wikimedia.org/wiki/
File:ICL_EDS80_at_Vintage_Computer_Festival_(1).jpg
> It wasn't me but one of the operators. She was very unhappy. It took me
> a while to convince her that I didn't do any of the power wiring.
> We got the local electricity board engineers for that.

I discovered the Mullard MW6-2 holds it's 25kv charge for quite a while.

Smolley <me@rest.uk> wrote:

> On Thu, 17 Aug 2023 14:56:16 +0100, steve1001908 wrote:
>
> > On Wed, 16 Aug 2023 14:31:52 +0100, Stephen Wolstenholme
> > <stephenwolstenholme30@outlook.com> wrote:
> >
> >>While working on TV I got all the usual shocks. The worst one on B&W TV
> >>was HT on a Rediffusion set. EHT was a much higher voltage but very low
> >>current. I never got a EHT shock from the very early colour sets I
> >>worked on with DER. I saw one of the other engineers get a shock from a
> >>colour TV EHT supply. It floored him. I had a tube discharge
> >>occasionally from new tubes (still boxed) arriving from the supplier. I
> >>always held on to the tube but swore at Mullard. Years later I started
> >>working on computer peripherals. I got a shock from an Ampex spooler
> >>motor servo when it decided to spool in the magnetic tape. That was a
> >>very bad shock and I had to have a lie down for a while. Everybody
> >>laughed!
> >
> > I've just remembered another "classic" shock from my mainframe computer
> > days. Some sites had rooms full of ICL EDS80 for data storage. Each
> > EDS80 was connected to three phase but only used one phases. Operators
> > would sometimes take a short cut through the gap between two EDS80 by
> > leaning on both drives. Just occasionally adjacent EDS were connected to
> > different phases. Thank the lord that the gray/orange cover paint was
> > quite thick. See
> > https://commons.wikimedia.org/wiki/
> File:ICL_EDS80_at_Vintage_Computer_Festival_(1).jpg
> > It wasn't me but one of the operators. She was very unhappy. It took me
> > a while to convince her that I didn't do any of the power wiring.
> > We got the local electricity board engineers for that.
>
> I discovered the Mullard MW6-2 holds it's 25kv charge for quite a while.

Yes, when I worked at Eddystone Radio they were still telling the tale
of the nosey, rather unpopular, manager who wandered through the
Development Department during the lunch hour and picked up a MW6-2 that
had been recently used. Out of curiosity he poked his finger down the
EHT socket and finished up juggling the tube for several seconds. He
didn't realise he was being watched; everyone in the works knew about it
within a few minutes.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

On 17/08/2023 21:37, Liz Tuddenham wrote:
> Yes, when I worked at Eddystone Radio they were still telling the tale

I forwarded that to a friend from college who worked at Eddystone for a
time.

His comments:

I had a set of the MW6-2 optics in my junk box back in my UK days. Made
a righteous searchlight, with a 300W projector lamp at the focus. I had
thoughts of putting a simple telescope in place of the CRT, to get a 6"
Schmitt astronomical telescope. Never got a round tuit, tho'. MW6-2 ran
some 25kV on the top, using a tripler rectifier as did the colour sets.
There was a tale when I was at Eddystone, that may be a corrupted
version of yours: around when they converted from red/black/green to
brown/blue/green-yellow mains leads, the lab bought a new VVM. Back
then, mains devices were sold with a loose lead, as there were so many
different AC plugs in UK. So the lab engineers had to wire it up. Did
they know the new colours? No way! Good democrats that they were, they
put it to a vote. Of course, wrong: they mixed up N & G. What they
didn't know was, when the bench had been wired up, years before in the
days before earth wires were used, the electrician had mixed up A & N!
So the VVM case was 'hot'. Adjacent on the bench was an archaic Marconi
signal generator, with much of its paint scuffed off the (properly
earthed) metal case. So the Chief Engineer leans on the Marconi, & picks
up the VVM's RF test probe - ZAPP! He subsided in a stream of profanity,
just as the works manager came in, with some important visitors in tow:
"How is everyone? How are things?"
As to the ICL disk drives, whatever was ANY "phase" voltage doing
connected to the case? I'd want the electrician's hide for that, even if
he did work for the Board.
Regards

"MB" <MB@nospam.net> wrote in message news:ubn699$5vdg$1@dont-email.me...
> As to the ICL disk drives, whatever was ANY "phase" voltage doing
> connected to the case? I'd want the electrician's hide for that, even if
> he did work for the Board.

When I worked at ICL in the 1990s, I remember us being kicked out of out
office/lab area into temporary accommodation while the lab was gutted and
re-fettled. When we were allowed back in, we discovered that consecutive
benches of the E-shaped row of benches (a spine with lots of side-branches)
had been connected to a different mains phase (the benches were labelled
with the standard phase colours) and there were big signs warning us not to
connect equipment from one bench to equipment on another (eg by RS-232 or
USB or Ethernet). This was a severe imposition and we had to buy a lot of
opto-isolators and/or juggle equipment between benches so things that
*needed* to be connected together (maybe temporarily during testing, not
necessarily permanently) could be connected.

I presume it was not normally a problem, but H&S had to cater (rightly) for
the "it will never happen" case of two pieces of equipment both suffering
live-chassis faults that didn't trip RCDs, and someone connecting USB
between those devices, which would have had 415 V (I think) between them.

Our head of department was not best pleased at the restriction, and was
seriously considering getting site services to put all of the lab area on
one phase, and then sharing the desk area between the other two phases, on
the grounds that connecting between lab and office was much less likely than
connecting between benches within the lab.

With our old talking newspapers being distributed on ordinary cassettes, we
used copiers that ran at 16 times speed. As they ran, some of them would
flash over between the tape and the metal centre hub. You could get a rather
large shock if you brushed against the spool hubs when it was operating. I
gues it was in effect a small sized windshurst machine.

Does anyone remember those electric shock machines you found in arcades.
Probably be banned today. You had two handles and the idea was to get them
as close together as you could before you had to let go. This effectively
put voltages across the chest, whoever though that was a good idea? I did
try one in my youth and you could in fact beat the thing simply by switching
your brain off. I think most of the issue with accidental shocks was that
they are unexpected, hence you are not prepared.
Brian

--

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"Smolley" <me@rest.uk> wrote in message news:ublinf$3r8sm$1@dont-email.me...
> On Thu, 17 Aug 2023 14:56:16 +0100, steve1001908 wrote:
>
>> On Wed, 16 Aug 2023 14:31:52 +0100, Stephen Wolstenholme
>> <stephenwolstenholme30@outlook.com> wrote:
>>
>>>While working on TV I got all the usual shocks. The worst one on B&W TV
>>>was HT on a Rediffusion set. EHT was a much higher voltage but very low
>>>current. I never got a EHT shock from the very early colour sets I
>>>worked on with DER. I saw one of the other engineers get a shock from a
>>>colour TV EHT supply. It floored him. I had a tube discharge
>>>occasionally from new tubes (still boxed) arriving from the supplier. I
>>>always held on to the tube but swore at Mullard. Years later I started
>>>working on computer peripherals. I got a shock from an Ampex spooler
>>>motor servo when it decided to spool in the magnetic tape. That was a
>>>very bad shock and I had to have a lie down for a while. Everybody
>>>laughed!
>>
>> I've just remembered another "classic" shock from my mainframe computer
>> days. Some sites had rooms full of ICL EDS80 for data storage. Each
>> EDS80 was connected to three phase but only used one phases. Operators
>> would sometimes take a short cut through the gap between two EDS80 by
>> leaning on both drives. Just occasionally adjacent EDS were connected to
>> different phases. Thank the lord that the gray/orange cover paint was
>> quite thick. See
>> https://commons.wikimedia.org/wiki/
> File:ICL_EDS80_at_Vintage_Computer_Festival_(1).jpg
>> It wasn't me but one of the operators. She was very unhappy. It took me
>> a while to convince her that I didn't do any of the power wiring.
>> We got the local electricity board engineers for that.
>
> I discovered the Mullard MW6-2 holds it's 25kv charge for quite a while.

Of course the hazing that used to go on when a new person came to work at
the factory. Somebody charged up a high voltage electrolytic and left it on
the desk or the chair while the new person was in the loo. I'm sure you can
imagine the result.
Brian

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"Liz Tuddenham" <liz@poppyrecords.invalid.invalid> wrote in message
news:1qfmmdd.1jvcii2l6wmj4N%liz@poppyrecords.invalid.invalid...
> Smolley <me@rest.uk> wrote:
>
>> On Thu, 17 Aug 2023 14:56:16 +0100, steve1001908 wrote:
>>
>> > On Wed, 16 Aug 2023 14:31:52 +0100, Stephen Wolstenholme
>> > <stephenwolstenholme30@outlook.com> wrote:
>> >
>> >>While working on TV I got all the usual shocks. The worst one on B&W TV
>> >>was HT on a Rediffusion set. EHT was a much higher voltage but very low
>> >>current. I never got a EHT shock from the very early colour sets I
>> >>worked on with DER. I saw one of the other engineers get a shock from a
>> >>colour TV EHT supply. It floored him. I had a tube discharge
>> >>occasionally from new tubes (still boxed) arriving from the supplier. I
>> >>always held on to the tube but swore at Mullard. Years later I started
>> >>working on computer peripherals. I got a shock from an Ampex spooler
>> >>motor servo when it decided to spool in the magnetic tape. That was a
>> >>very bad shock and I had to have a lie down for a while. Everybody
>> >>laughed!
>> >
>> > I've just remembered another "classic" shock from my mainframe computer
>> > days. Some sites had rooms full of ICL EDS80 for data storage. Each
>> > EDS80 was connected to three phase but only used one phases. Operators
>> > would sometimes take a short cut through the gap between two EDS80 by
>> > leaning on both drives. Just occasionally adjacent EDS were connected
>> > to
>> > different phases. Thank the lord that the gray/orange cover paint was
>> > quite thick. See
>> > https://commons.wikimedia.org/wiki/
>> File:ICL_EDS80_at_Vintage_Computer_Festival_(1).jpg
>> > It wasn't me but one of the operators. She was very unhappy. It took me
>> > a while to convince her that I didn't do any of the power wiring.
>> > We got the local electricity board engineers for that.
>>
>> I discovered the Mullard MW6-2 holds it's 25kv charge for quite a while.
>
> Yes, when I worked at Eddystone Radio they were still telling the tale
> of the nosey, rather unpopular, manager who wandered through the
> Development Department during the lunch hour and picked up a MW6-2 that
> had been recently used. Out of curiosity he poked his finger down the
> EHT socket and finished up juggling the tube for several seconds. He
> didn't realise he was being watched; everyone in the works knew about it
> within a few minutes.
>
>
> --
> ~ Liz Tuddenham ~
> (Remove the ".invalid"s and add ".co.uk" to reply)
> www.poppyrecords.co.uk

Yes at Redeffusion the soak racks on a roller with sliding sockets started
life on one phase, but the Leccy board paid us a visit saying that the
combination of half wave rectification and being all on the same phase was
unbalancing the local grid. They had to divide the prsee set up rollers from
the soak test ones. Because this was mostly valve equipment they did not
want the multiple warm up time when doing things like convergence as it
could drift in the first few minutes.
Brian

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"NY" <me@privacy.invalid> wrote in message
news:ubnbhl$6o7a$1@dont-email.me...
> "MB" <MB@nospam.net> wrote in message news:ubn699$5vdg$1@dont-email.me...
>> As to the ICL disk drives, whatever was ANY "phase" voltage doing
>> connected to the case? I'd want the electrician's hide for that, even if
>> he did work for the Board.
>
> When I worked at ICL in the 1990s, I remember us being kicked out of out
> office/lab area into temporary accommodation while the lab was gutted and
> re-fettled. When we were allowed back in, we discovered that consecutive
> benches of the E-shaped row of benches (a spine with lots of
> side-branches) had been connected to a different mains phase (the benches
> were labelled with the standard phase colours) and there were big signs
> warning us not to connect equipment from one bench to equipment on another
> (eg by RS-232 or USB or Ethernet). This was a severe imposition and we had
> to buy a lot of opto-isolators and/or juggle equipment between benches so
> things that *needed* to be connected together (maybe temporarily during
> testing, not necessarily permanently) could be connected.
>
> I presume it was not normally a problem, but H&S had to cater (rightly)
> for the "it will never happen" case of two pieces of equipment both
> suffering live-chassis faults that didn't trip RCDs, and someone
> connecting USB between those devices, which would have had 415 V (I think)
> between them.
>
> Our head of department was not best pleased at the restriction, and was
> seriously considering getting site services to put all of the lab area on
> one phase, and then sharing the desk area between the other two phases, on
> the grounds that connecting between lab and office was much less likely
> than connecting between benches within the lab.

On Wed, 16 Aug 2023 16:37:01 +0100, MB wrote:

> On 16/08/2023 15:52, tony sayer wrote:
>> As to EHT shocks yep a few colour Tubes were dropped owing the charge
>> rebuilding on CRTs made a bloody mess being b dropped on the works
>> floor!
>
>
> Many says that RF burns are the worse and tend not to heal up.
>
> I once disconnected a feeder with a few KW or RF on it (I had been
> assured it was turned off). It was very impressive, I heard a 'clunk'
> from the other end of the building as the amplifier tripped off but no
> arcing or burning.

I used to work with a guy at International Aeradio who over his working
life had built up a huge collection of RF burns to his head. He would
regularly walk into the screened room where the transmitter power feeders
were.

In message <ubnejs$76el$1@dont-email.me> at Fri, 18 Aug 2023 10:45:28,
Brian Gaff <brian1gaff@gmail.com> writes
>Of course the hazing that used to go on when a new person came to work at
>the factory. Somebody charged up a high voltage electrolytic and left it on
>the desk or the chair while the new person was in the loo. I'm sure you can
>imagine the result.
> Brian
>
A colleague at work used to recount how, when working with some high
voltages, at the end of work he once carefully grounded a capacitor
terminal that had been at + whatever it was volts, to discharge it. And
he then touched the other terminal ...

Voltage is relative!

(I don't know if true. Can't see why not.)
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

A true-born Englishman does not know any language. He does not speak English
too well either but, at least, he is not proud of this. He is, however,
immensely proud of not knowing any foreign languages. (George Mikes, "How to
be Inimitable" [1960].)

Brian Gaff <brian1gaff@gmail.com> wrote:

> With our old talking newspapers being distributed on ordinary cassettes, we
> used copiers that ran at 16 times speed. As they ran, some of them would
> flash over between the tape and the metal centre hub. You could get a rather
> large shock if you brushed against the spool hubs when it was operating. I
> gues it was in effect a small sized windshurst machine.

I had a similar problem when designing a playback machine for
Recordgraph film loops. They were 50ft long and wound into an endless
hank running around a circle of rollers, the film was pulled out from
the cente, played and returned to the outside. As the hank revolved,
the turns would shuffle over each other as they neared the centre and
each turn became slightly shorter.

I found I was getting loud clicks on the playback amplifier that were
nothing to do with the recording. In the dark, blue flashes were
visible between the layers of the hank and these coincided with the loud
clicks.

At a position where the film entered the hank I had installed a wiper*
to colect any dirt, this was charging the film. A pair of carbon fibre
brushes just after the wiper, one each side of the film, solved the
problem.

[* The first attempt at a wiper was a felt sleeve on a nylon bar, but
this was too coarse to penetrate the grooves, so a fine velvet sleeve
was used instead.. We made an official report on the design of the
machine in which the wiper systems was described as a 'want'; I don't
think anyone bothered to read it or they would have discovered that this
was because it was a 'long felt want' ]

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

In message <1qfo5fn.1th04711md72heN%liz@poppyrecords.invalid.invalid> at
Fri, 18 Aug 2023 17:37:19, Liz Tuddenham
<liz@poppyrecords.invalid.invalid> writes
[]
>I had a similar problem when designing a playback machine for
>Recordgraph film loops. They were 50ft long and wound into an endless
>hank running around a circle of rollers, the film was pulled out from
>the cente, played and returned to the outside. As the hank revolved,
>the turns would shuffle over each other as they neared the centre and
>each turn became slightly shorter.

What was Recordgraph - optical film? Those things with grooves on film
that had some popularity in Germany (though I think they had a different
name, something with band in it - since they were played by basically a
record cartridge I don't think they'd be so susceptible to what
follows)?
>
>I found I was getting loud clicks on the playback amplifier that were
>nothing to do with the recording. In the dark, blue flashes were
>visible between the layers of the hank and these coincided with the loud
>clicks.
>
>At a position where the film entered the hank I had installed a wiper*
>to colect any dirt, this was charging the film. A pair of carbon fibre
>brushes just after the wiper, one each side of the film, solved the
>problem.
>
>
>[* The first attempt at a wiper was a felt sleeve on a nylon bar, but
>this was too coarse to penetrate the grooves, so a fine velvet sleeve
>was used instead.. We made an official report on the design of the
>machine in which the wiper systems was described as a 'want'; I don't
>think anyone bothered to read it or they would have discovered that this
>was because it was a 'long felt want' ]
>
I just _love_ it when something like that gets into a report. We had
something for testing digital comm.s called a bit error rate tester,
alias BERT, which certainly found its way into the panel labels; there
was the time when Grundig had lots of "-boy" radios (Yacht-boy,
Call-boy) when someone in our department called his design call-girl,
but that got spotted. My favourite such thing was an article on the use
of Doppler direction-finding aerials, which managed to get a reference
to the Monty Python architect sketch tucked in among all the other
academic references.
>
>
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

"I do not feel obliged to believe that the God who endowed me with sense,
reason, and intellect intends me to forego their use". - Gallileo Gallilei

J. P. Gilliver <G6JPG@255soft.uk> wrote:

> In message <1qfo5fn.1th04711md72heN%liz@poppyrecords.invalid.invalid> at
> Fri, 18 Aug 2023 17:37:19, Liz Tuddenham
> <liz@poppyrecords.invalid.invalid> writes
> []
> >I had a similar problem when designing a playback machine for
> >Recordgraph film loops. They were 50ft long and wound into an endless
> >hank running around a circle of rollers, the film was pulled out from
> >the cente, played and returned to the outside. As the hank revolved,
> >the turns would shuffle over each other as they neared the centre and
> >each turn became slightly shorter.
>
> What was Recordgraph - optical film?

Mechanical film. It was a long-playing professional format with grooves
embossed on 35mm uncoated leader film. The' endless' loop did about 100
turns with the embossing head shifted over by 0.010" at the end of each
turn.

There is a full description at:
< http://www.poppyrecords.co.uk/other/recordgraph/recordgraph.htm>

> Those things with grooves on film
> that had some popularity in Germany (though I think they had a different
> name, something with band in it - ...

The one I know about was a Tefifon, but there were lots of different
types of media with similar ideas in the 1930s. Most systems that cut
the groove used cellulose nitrate; cellulose acetate wouldn't cut
smoothly and just tore noisily. The Recordgraph and Dictaphone systems
used cellulose acetate for safety, so they had to emboss the groove,
rather than cut it. I think the Tefifon used a cut master recording,
possibly on nitrate, which was then electroplated and pressed into an
acetate belt.

--
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(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

Oh dear.
It reminds me of the world is short of Tuits. As in I'll get a round to it
but never do.

--

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"Liz Tuddenham" <liz@poppyrecords.invalid.invalid> wrote in message
news:1qfo5fn.1th04711md72heN%liz@poppyrecords.invalid.invalid...
> Brian Gaff <brian1gaff@gmail.com> wrote:
>
>> With our old talking newspapers being distributed on ordinary cassettes,
>> we
>> used copiers that ran at 16 times speed. As they ran, some of them would
>> flash over between the tape and the metal centre hub. You could get a
>> rather
>> large shock if you brushed against the spool hubs when it was operating.
>> I
>> gues it was in effect a small sized windshurst machine.
>
> I had a similar problem when designing a playback machine for
> Recordgraph film loops. They were 50ft long and wound into an endless
> hank running around a circle of rollers, the film was pulled out from
> the cente, played and returned to the outside. As the hank revolved,
> the turns would shuffle over each other as they neared the centre and
> each turn became slightly shorter.
>
> I found I was getting loud clicks on the playback amplifier that were
> nothing to do with the recording. In the dark, blue flashes were
> visible between the layers of the hank and these coincided with the loud
> clicks.
>
> At a position where the film entered the hank I had installed a wiper*
> to colect any dirt, this was charging the film. A pair of carbon fibre
> brushes just after the wiper, one each side of the film, solved the
> problem.
>
>
> [* The first attempt at a wiper was a felt sleeve on a nylon bar, but
> this was too coarse to penetrate the grooves, so a fine velvet sleeve
> was used instead.. We made an official report on the design of the
> machine in which the wiper systems was described as a 'want'; I don't
> think anyone bothered to read it or they would have discovered that this
> was because it was a 'long felt want' ]
>
>
>
> --
> ~ Liz Tuddenham ~
> (Remove the ".invalid"s and add ".co.uk" to reply)
> www.poppyrecords.co.uk