I am in the UK.

I have been cleaning out the dust from the inside of my monitor and I
just moved a few pots to make sure their tracks are clean and returned
the pots to how they were.

In fact the only pots I can find are three right next to the coil on the
neck of the picture tube and they are marked:

Y-HC: Y and in small letters, HC
Delta V: capital delta symbol then V
YV: Y and in a small letter, V

What do these do?

To be prfectly honest I think I may have not quite returned them to
their original postion but might be 20 or 30 degrees out.

Can I adjust them with the monitor on? Of course I won't be touching
any HT parts but I wonder if they are inherently too close to the HT to
adjust while the monitor is on?

Must I use an insulated trimming tool rather than a meta scredriver?

Years ago, my Dad, a learned professional and well respected in his
field, told me this story when I was a boy.

One day he was sitting with all the other well respected learned
professionals in the lounge in the building where they worked.

They had just gotten a new and very expensive piece of equipment
installed, and the installer was training them in the procedures for
using their new equipment.

The equipment was a COLOR television. The first one that many of the
people in the room had ever seen.

After the speech, asked the respected learned professionals in the room
if they wanted the absolute best color picture they could get on this
tv. "Well, of course.", somebody replied.

The installer opened a little door in the front of the device and
pointed to a little row of colored knobs he'd just finished adjusting.
See these little knobs here?

In rapt attention, they all stared...yes..

DON'T F*** WITH THEM.

"Andy" wrote in message
...
I am in the UK.

I have been cleaning out the dust from the inside of my monitor and I
just moved a few pots to make sure their tracks are clean and returned
the pots to how they were.


EEK, if it ain't broke, don't fix it.

One of my first childhood 'accidents' was messing with the myriad of
alignment pots which were too easily accessable on the back of our old
Philips colour TV.

Moving pots which have not been touched for years can also cause problems
and can crack an old, seized shaft or rip up the carbon track.....

//Clive.

"Andy" wrote in message
...
I am in the UK.

I have been cleaning out the dust from the inside of my monitor and I
just moved a few pots to make sure their tracks are clean and returned
the pots to how they were.


With respect, that was an extremely foolish thing to do. If you don't
understand the inside of mains operated equipment, you shouldn't be inside
it, let alone turning adjustments. If the pots had been dirty but producing
no symptoms, turning them could have caused a fault that wasn't there before
by dragging the dirt under the wiper.


In fact the only pots I can find are three right next to the coil on the
neck of the picture tube and they are marked:

Y-HC: Y and in small letters, HC
Delta V: capital delta symbol then V
YV: Y and in a small letter, V

What do these do?


They are convergence pots. They alter the relationship of the geometries
between the beams. The red, green and blue images which make up the colour
picture on your monitor must overlap as close to perfectly as possible,
otherwise you will see red, green or blue fringes on different parts of the
image. They should only ever be altered by someone who understands how to
set them up- they can be very difficult to get back if you don't know what
you're doing.

If the picture looks OK, you've got away with it.

At least you didn't alter the static convergence rings on the CRT neck- that
really would have caused problems.

Dave

Andy wrote:
I am in the UK.

I have been cleaning out the dust from the inside of my monitor and I
just moved a few pots to make sure their tracks are clean and returned
the pots to how they were.


Totally unnecessary operation but as you've fiddled now, it can't hurt
to mess around with some insulated tools and some safety knowledge.
Track down the Sci.Electronics.Rapair FAQ site and read.. (or skip the
monitor if the picture is bad, and get a better one from freecycle.org)

Long time ago a friend bought (then) a quite nice secondhand VHS video
recorder (JVC 3V43) with HiFi heads, still frame advance and all the
toys. Plugged it into his television set and noticed the picture tearing
across from the top. So he 'fixed' it. Took the VCR covers off, got some
sand paper, scrubbed the head drum - found 4 black specks wouldn't
shift. So took a screwdriver and neatly chipped them away...

Yes, this idiot computer programmer's TV was to blame (time constant not
set for VCR) but the video head was now completely beyond service - and
cost to replace as much as the whole recorder cost him :-(

--
Adrian C

Adrian C wrote in
:

Long time ago a friend bought (then) a quite nice secondhand VHS video
recorder (JVC 3V43) with HiFi heads, still frame advance and all the
toys. Plugged it into his television set and noticed the picture
tearing across from the top. So he 'fixed' it. Took the VCR covers
off, got some sand paper, scrubbed the head drum - found 4 black
specks wouldn't shift. So took a screwdriver and neatly chipped them
away...
Yes, this idiot computer programmer's TV was to blame (time constant
not set for VCR) but the video head was now completely beyond service
- and cost to replace as much as the whole recorder cost him :-(

LOL

I'm in two minds as to whether to dismiss this story as apocryphal or to
accept that there really *are* people who would do this!

I once managed to resurrect my old VCR which started producing *very* snowy
pictures after a tape got jammed inside it and must have shed some oxide
onto the heads. However that was with the aid of a cotton-wool ear-bud
soaked in isopropyl alcohol and very gently stroked over the heads - and
only after a head-cleaning cassette had proved to have no effect. The amount
of crud that came off was quite remarkable. After allowing time for the
alcohol to evaporate (I didn't want the tape sticking to the drum!) I
gingerly fired up the VCR and the picture improved over the course of a few
minutes' playing. After a bit longer, the hi-fi sound came back as well.

But to attack a video head with sandpaper and a screwdriver... gulp!



I'm firmly of the school of thought that says "look as much as you like, but
if it's not broken, don't try to 'fix' it". And when EHT is involved, I'd be
very reluctant to open the case of a monitor, even after it's been switched
off for a while - capacitors can store lethal voltages. If I was going to
attempt to tweak the pots, I'd use a long nylon screwdriver and I'd just
tickle each pot in case the setting was very critical. To be "almost right,
but maybe 20 or 30 degrees out" sounds rather vague.

"Adrian C" wrote in message
...


Yes, this idiot computer programmer's TV was to blame (time constant not
set for VCR) but the video head was now completely beyond service - and
cost to replace as much as the whole recorder cost him :-(


Reminds me of when I walked into a friends room to find him armed with a
carving knife in one hand and the bezel of his computer monitor in the
other.

Turned out he had a computer game with some text which scrolled at the very
bottom on the screen and was partially obscured by the CRT surround which he
intended to carve away. I quickly pointed out the V-height pot at the back
of his monitor but it took hours to rebuild it as to get the bezel off he
had unplugged every cable and HT lead he could see.

I really am surprised we don't see more people electrocuted whilst messing
around in the back of TVs and monitors...

//Clive.

Couldn't this also have been a result of the VCR's back tension being out of
adjustment or was this occuring only with the regular cable signal?

Bruce


"Adrian C" wrote in message
...
Andy wrote:
I am in the UK.

I have been cleaning out the dust from the inside of my monitor and I
just moved a few pots to make sure their tracks are clean and returned
the pots to how they were.


Totally unnecessary operation but as you've fiddled now, it can't hurt to
mess around with some insulated tools and some safety knowledge. Track
down the Sci.Electronics.Rapair FAQ site and read.. (or skip the monitor
if the picture is bad, and get a better one from freecycle.org)

Long time ago a friend bought (then) a quite nice secondhand VHS video
recorder (JVC 3V43) with HiFi heads, still frame advance and all the toys.
Plugged it into his television set and noticed the picture tearing across
from the top. So he 'fixed' it. Took the VCR covers off, got some sand
paper, scrubbed the head drum - found 4 black specks wouldn't shift. So
took a screwdriver and neatly chipped them away...

Yes, this idiot computer programmer's TV was to blame (time constant not
set for VCR) but the video head was now completely beyond service - and
cost to replace as much as the whole recorder cost him :-(

--
Adrian C

"Martin Underwood" wrote in message
...
I once managed to resurrect my old VCR which started producing *very*
snowy pictures after a tape got jammed inside it and must have shed some
oxide onto the heads. However that was with the aid of a cotton-wool
ear-bud soaked in isopropyl alcohol and very gently stroked over the
heads - and only after a head-cleaning cassette had proved to have no
effect.

Cotton buds should not be used on video heads IMO. The fibres can snag and
break off the heads, or become entangled. There's only two things I ever put
near the drum to clean it- chamois swabs and copier paper, both with
isopropyl alcohol. Both clean the heads very well indeed, and even dry
copier paper does a safe job if one doesn't have the proper tools handy.

Dave

Chris Vowles wrote in
:

Andy wrote:
I am in the UK.

I hate to admit this but it rang too much of a bell not to reply ....
as a teenager I had a cheap 14" TV where the image was not in the
correct place,
I turned some very similar sounding pots with a non insulated
screwdriver which came with a meccano set !
Everything went fine with the picture changing until I moved around to
have a better look at the screen and the point of the screwdriver
slipped out of the pot and onto a live pin on the board ....
next thing I knew I was sat on the floor on the other side of the room
with a sore arm and a blackened screwdriver

I assume that this was mains voltage rather than EHT, otherwise you probably
wouldn't be around to tell the tale.

I once made the elementary mistake of doing some work on an old mains-driven
tape-recorder. I'd switched it off at the power-switch on the tape-recorder,
but I'd forgotten to unplug it. All was fine until - you've guessed - my
finger happened to touch the terminals of the switch. Likewise, I was left
with a very sore, tingling arm - and a feeling that I had just lost one of
my nine lives.


I did get an electrical engineering degree a few years later ......

Same here.

Bruce H wrote:
Couldn't this also have been a result of the VCR's back tension being out of
adjustment or was this occuring only with the regular cable signal?

Nope. He got another video recorder and complained of the same problem.
Didn't take us long to figure out what was up - around the mid
eighties it was fairly common knowledge (here in the UK anyway) that one
of the UHF preset channels (normally the last one of 4 or 8) on a TV set
was reserved for VCR use - he'd used another.

--
Adrian C

Martin Underwood wrote:
All was fine until - you've guessed - my
finger happened to touch the terminals of the switch. Likewise, I was left
with a very sore, tingling arm - and a feeling that I had just lost one of
my nine lives.

I did get an electrical engineering degree a few years later ......

Same here.



Took apart (to save the bits) the SMPS from an old Sony betamax video
recorder forgetting to discharge some heavy capacitors first. My stray
fingers met some large DC voltage and by instinct / reflex I flung the
module across the room cutting myself badly on a fold in the metal work.

That electronics degree taught me nothing...

--
Adrian C

In article ,
Adrian C wrote:
Bruce H wrote:
Couldn't this also have been a result of the VCR's back tension being
out of adjustment or was this occuring only with the regular cable
signal?

Nope. He got another video recorder and complained of the same problem.
Didn't take us long to figure out what was up - around the mid
eighties it was fairly common knowledge (here in the UK anyway) that one
of the UHF preset channels (normally the last one of 4 or 8) on a TV set
was reserved for VCR use - he'd used another.

The last channel selector altered the time constant in the line sync
locking so that it could cope with unstable vcr signals.

--
From KT24 - in drought-ridden Surrey

Using a RISC OS5 computer

charles wrote in
:

In article ,
Adrian C wrote:
Bruce H wrote:
Couldn't this also have been a result of the VCR's back tension
being out of adjustment or was this occuring only with the regular
cable signal?

Nope. He got another video recorder and complained of the same
problem. Didn't take us long to figure out what was up - around
the mid
eighties it was fairly common knowledge (here in the UK anyway) that
one of the UHF preset channels (normally the last one of 4 or 8) on
a TV set was reserved for VCR use - he'd used another.

The last channel selector altered the time constant in the line sync
locking so that it could cope with unstable vcr signals.

What was the disadvantage of of using the VCR time constant setting for
off-air reception? Presumably there must have been a disadvantage otherwise
all the channel positions would have been permanently set to the VCR time
constant.

I know my TV (bought in 2000) has different settings on its SCART sockets
than on its phono and S-Video aux inputs on the front panel: the phono and
S-video sockets have more problem locking onto the video output from my
laptop which evidently isn't quite 625/50 specification, whereas the SCARTs
are much more tolerant.

"Martin Underwood" writes:

Chris Vowles wrote in
:

Andy wrote:
I am in the UK.

I hate to admit this but it rang too much of a bell not to reply ....
as a teenager I had a cheap 14" TV where the image was not in the
correct place,
I turned some very similar sounding pots with a non insulated
screwdriver which came with a meccano set !
Everything went fine with the picture changing until I moved around to
have a better look at the screen and the point of the screwdriver
slipped out of the pot and onto a live pin on the board ....
next thing I knew I was sat on the floor on the other side of the room
with a sore arm and a blackened screwdriver

I assume that this was mains voltage rather than EHT, otherwise you probably
wouldn't be around to tell the tale.

Actually, this is a misconception that can prove quite lethal. Generally,
the mains voltage - 115 VAC or 230 VAC - can be more dangerous than the
25 kV or whataver.

Touching the HV may throw you across the room due to the charge on the
CRT capacitance, but probably won't kill you except on a really bad day.
Aside from the capacitor, there is too little current to do any harm.

There are AMPs available from the mains voltage.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
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On Tue, 2 May 2006 18:17:10 +0100, "Martin Underwood"
wrote:

I assume that this was mains voltage rather than EHT, otherwise you probably
wouldn't be around to tell the tale.

Naah. It's the volts that jolts but the mills that kills.

In a Vacuum tube colour set CA 1969 about the safest thing to get a
shock off was the 25 Kv. Or so they taught us at BBC training school
Evesham. IIRC effectively limited at about 2.5 ma. OTOH.

http://www.r-type.org/exhib/aaa0021.htm

"The normal anode voltage of 160 V is designed to be exceeded by
pulses of up to 8,000 Volts and 1.4 Amps. 8-((


I once made the elementary mistake of doing some work on an old mains-driven
tape-recorder. I'd switched it off at the power-switch on the tape-recorder,
but I'd forgotten to unplug it. All was fine until - you've guessed - my
finger happened to touch the terminals of the switch. Likewise, I was left
with a very sore, tingling arm - and a feeling that I had just lost one of
my nine lives.


I did get an electrical engineering degree a few years later ......

Same here.


DG

In article , Martin
Underwood wrote:
The last channel selector altered the time constant in the line sync
locking so that it could cope with unstable vcr signals.

What was the disadvantage of of using the VCR time constant setting for
off-air reception? Presumably there must have been a disadvantage otherwise
all the channel positions would have been permanently set to the VCR time
constant.

Greater susceptibility to noise on received sugnals, which would cause
raggedness of vertical lines due to variations in line timing. There's a
reason for using what was called "flywheel sync". A shorter time constant
effectively made it work with a smaller "flywheel" - OK for clean locally
generated video signals, but not good for off-air material.

Rod.

In article , Chris Vowles wrote:
Everything went fine with the picture changing until I moved around to
have a better look at the screen and the point of the screwdriver
slipped out of the pot and onto a live pin on the board ....
next thing I knew I was sat on the floor on the other side of the room
with a sore arm and a blackened screwdriver

I did get an electrical engineering degree a few years later ......

Excellent. First the practical, then the theory. If you survive the first
and are still interested, you're qualified to have a go at the second.
:-)

Rod.

Derek ^ wrote:
On Tue, 2 May 2006 18:17:10 +0100, "Martin Underwood"
wrote:

I assume that this was mains voltage rather than EHT, otherwise you probably
wouldn't be around to tell the tale.


Naah. It's the volts that jolts but the mills that kills.

In a Vacuum tube colour set CA 1969 about the safest thing to get a
shock off was the 25 Kv. Or so they taught us at BBC training school
Evesham. IIRC effectively limited at about 2.5 ma. OTOH.


In the late sixties I worked with a BBC Electronic Services engineer who
regularly used to check whether EHT was present on a faulty monitor by
removing the plug from the tube and sticking his thumb on it.

Chris Y

"Martin Underwood" wrote in message
...

I assume that this was mains voltage rather than EHT, otherwise you
probably wouldn't be around to tell the tale.


The EHT in a TV (anode voltage) is *far* less of a threat to life than the
mains.


Dave

In the late sixties I worked with a BBC Electronic Services engineer who
regularly used to check whether EHT was present on a faulty monitor by
removing the plug from the tube and sticking his thumb on it.

Ouch! That hurts.. I got zapped from the neckboard on my ms pacman cocktail
table while reaching around inside with it on.. That was a mistake that I
don't plan to repeat any time soon.. ;-)

- Mike

Chris Youlden wrote:
Derek ^ wrote:

On Tue, 2 May 2006 18:17:10 +0100, "Martin Underwood"
wrote:

I assume that this was mains voltage rather than EHT, otherwise you
probably wouldn't be around to tell the tale.



Naah. It's the volts that jolts but the mills that kills.

In a Vacuum tube colour set CA 1969 about the safest thing to get a
shock off was the 25 Kv. Or so they taught us at BBC training school
Evesham. IIRC effectively limited at about 2.5 ma. OTOH.


In the late sixties I worked with a BBC Electronic Services engineer who
regularly used to check whether EHT was present on a faulty monitor by
removing the plug from the tube and sticking his thumb on it.

My grandfather's Christmas party piece was to open up the tin box that
housed the EHT rectifier, and with a damp wooden handle screwdriver,
draw an arc from the anode terminal.

--
Mark
Please replace invalid and invalid with gmx and net to reply.

In article , Mark Carver wrote:
In the late sixties I worked with a BBC Electronic Services engineer who
regularly used to check whether EHT was present on a faulty monitor by
removing the plug from the tube and sticking his thumb on it.

My grandfather's Christmas party piece was to open up the tin box that
housed the EHT rectifier, and with a damp wooden handle screwdriver,
draw an arc from the anode terminal.

I remember one of those translucent orange handled screwdrivers would do
quite well too. I've no idea what the resistance of the handle would be, but
I'd trust it to be a bit more consistent than a wooden spoon.

Slightly safer now of course, though not quite so much fun, because voltage
triplers are the usual thing - not such a big spark.

Rod.

Roderick Stewart wrote:

In article , Mark Carver wrote:
In the late sixties I worked with a BBC Electronic Services
engineer who regularly used to check whether EHT was present on a
faulty monitor by removing the plug from the tube and sticking
his thumb on it.

My grandfather's Christmas party piece was to open up the tin box
that housed the EHT rectifier, and with a damp wooden handle
screwdriver, draw an arc from the anode terminal.

I remember one of those translucent orange handled screwdrivers would
do quite well too. I've no idea what the resistance of the handle
would be, but I'd trust it to be a bit more consistent than a wooden
spoon.

Slightly safer now of course, though not quite so much fun, because
voltage triplers are the usual thing - not such a big spark.

Rod.

My father had an eht voltmeter that consisted of a calibrated spark
gap. You turned a knob bringing the balls closer together until the
spark jumped the gap. Then you read off the voltage on a scale.

--
Ashley
For Windsor weather see www.snglinks.com/wx/

Clive wrote:
"Ashley" wrote in message
...


My father had an eht voltmeter that consisted of a calibrated spark
gap. You turned a knob bringing the balls closer together until the
spark jumped the gap. Then you read off the voltage on a scale.


How accurate would this have been ?

Wouldn't humidity / air quality have a measurable an effect on a spark gap ?

Were they not sealed devices ?

Roderick Stewart writes:

In article , Mark Carver wrote:
In the late sixties I worked with a BBC Electronic Services engineer who
regularly used to check whether EHT was present on a faulty monitor by
removing the plug from the tube and sticking his thumb on it.

My grandfather's Christmas party piece was to open up the tin box that
housed the EHT rectifier, and with a damp wooden handle screwdriver,
draw an arc from the anode terminal.

I remember one of those translucent orange handled screwdrivers would do
quite well too. I've no idea what the resistance of the handle would be, but
I'd trust it to be a bit more consistent than a wooden spoon.

Slightly safer now of course, though not quite so much fun, because voltage
triplers are the usual thing - not such a big spark.

The anode terminal of the HV rectifier tube was connected to the flyback
which was 15.7 kHz AC - similar to the output from a small Tesla
coil. So, as long as the screwdriver had some capacitance, the conductivity
of the handle probably didn't matter much.

With modern flybacks, the output is DC filtered by the CRT capacitance,
so the effects are quite different.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
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In article , Sam Goldwasser wrote:
Slightly safer now of course, though not quite so much fun, because voltage
triplers are the usual thing - not such a big spark.

The anode terminal of the HV rectifier tube was connected to the flyback
which was 15.7 kHz AC - similar to the output from a small Tesla
coil. So, as long as the screwdriver had some capacitance, the conductivity
of the handle probably didn't matter much.

I was referring to the fact that most modern EHT circuits will only have 8kV
pulses instead of 25kV pulses, because they use a diode/capacitor multiplier and
a lower voltage transformer.

With modern flybacks, the output is DC filtered by the CRT capacitance,
so the effects are quite different.

That happens anyway doesn't it? The coatings on the inside and outside of the
bowl of the CRT constitute the EHT smoothing capacitor.

Rod.

Roderick Stewart writes:

In article , Sam Goldwasser wrote:
Slightly safer now of course, though not quite so much fun, because voltage
triplers are the usual thing - not such a big spark.

The anode terminal of the HV rectifier tube was connected to the flyback
which was 15.7 kHz AC - similar to the output from a small Tesla
coil. So, as long as the screwdriver had some capacitance, the conductivity
of the handle probably didn't matter much.

I was referring to the fact that most modern EHT circuits will only have 8kV
pulses instead of 25kV pulses, because they use a diode/capacitor multiplier and
a lower voltage transformer.

With modern flybacks, the output is DC filtered by the CRT capacitance,
so the effects are quite different.

That happens anyway doesn't it? The coatings on the inside and outside of the
bowl of the CRT constitute the EHT smoothing capacitor.

What I was trying to say is that in a modern CRT TV or monitor, there is
no place to find the full HV pulses - 5 kV or 25 kV - since the only
output of the flyback goes directly to the CRT anode and its capacitance.

In old once, the flyback output went to the 1B3 (or whatever) anode and
was AC at that point.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
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In article , Sam Goldwasser wrote:
With modern flybacks, the output is DC filtered by the CRT capacitance,
so the effects are quite different.

That happens anyway doesn't it? The coatings on the inside and outside of the
bowl of the CRT constitute the EHT smoothing capacitor.

What I was trying to say is that in a modern CRT TV or monitor, there is
no place to find the full HV pulses - 5 kV or 25 kV - since the only
output of the flyback goes directly to the CRT anode and its capacitance.

If you mean the multiplier, then yes, it would incorporate the EHT rectifier which
would otherwise have been a separate diode. The output terminal of the multilplier
unit would be the cathode of the diode, so no AC at that point.

In old once, the flyback output went to the 1B3 (or whatever) anode and
was AC at that point.

Yes, a whacking great pulse equal to the full EHT potential onto the anode of a
separate diode. Treat with extreme respect!

Rod.

On 02 May 2006, Dave wrote:

They are convergence pots. They alter the relationship of the
geometries between the beams. The red, green and blue images which
make up the colour picture on your monitor must overlap as close to
perfectly as possible, otherwise you will see red, green or blue
fringes on different parts of the image. They should only ever be
altered by someone who understands how to set them up- they can be
very difficult to get back if you don't know what you're doing.

If the picture looks OK, you've got away with it.


Phew!



At least you didn't alter the static convergence rings on the CRT
neck- that really would have caused problems.

Hmmm. Let me have a look and see if I can move .... :-)

On 02 May 2006, Martin wrote:

I assume that this was mains voltage rather than EHT, otherwise you
probably wouldn't be around to tell the tale.


i thought that some posts to a very recent thread said that HT was not
actually so very dangerous but would throw you across a room (the main
danger being how you landed).

Andy writes:

On 02 May 2006, Dave wrote:

They are convergence pots. They alter the relationship of the
geometries between the beams. The red, green and blue images which
make up the colour picture on your monitor must overlap as close to
perfectly as possible, otherwise you will see red, green or blue
fringes on different parts of the image. They should only ever be
altered by someone who understands how to set them up- they can be
very difficult to get back if you don't know what you're doing.

If the picture looks OK, you've got away with it.

Phew!

At least you didn't alter the static convergence rings on the CRT
neck- that really would have caused problems.

Hmmm. Let me have a look and see if I can move .... :-)

Everyone loves to diddle with those magnet rings....

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

In article , Alex Coleman wrote:
I assume that this was mains voltage rather than EHT, otherwise you
probably wouldn't be around to tell the tale.

i thought that some posts to a very recent thread said that HT was not
actually so very dangerous but would throw you across a room (the main
danger being how you landed).

Electricity doesn't "throw you across a room", so if somebody's
description included this statement you know how much you can trust the
rest of it.

If you find yourself somewhere else in the room after an electric shock,
it will have been your own muscles that put you there.

Rod.

On 06 May 2006, Roderick
wrote:

In article , Alex Coleman wrote:
I assume that this was mains voltage rather than EHT, otherwise
you probably wouldn't be around to tell the tale.

i thought that some posts to a very recent thread said that HT was
not actually so very dangerous but would throw you across a room
(the main danger being how you landed).

Electricity doesn't "throw you across a room", so if somebody's
description included this statement you know how much you can trust
the rest of it.

If you find yourself somewhere else in the room after an electric
shock, it will have been your own muscles that put you there.


Steady on Roderick! Now that's a wee bit pedantic.
Are you not happy with ellipsis? Otherwise we will have to sort out
things like:

Water does not satisfiy your thirst, it satisfies your body's thirst.

A car does not run on pertrol, a car's engine runs on petrol.

You do not watch television, you watch images on the tube of the
television.

PHEW!
:-0

Alex Coleman spake thus:

On 06 May 2006, Roderick
wrote:

In article , Alex Coleman wrote:

I assume that this was mains voltage rather than EHT, otherwise
you probably wouldn't be around to tell the tale.

i thought that some posts to a very recent thread said that HT was
not actually so very dangerous but would throw you across a room
(the main danger being how you landed).

Electricity doesn't "throw you across a room", so if somebody's
description included this statement you know how much you can trust
the rest of it.

If you find yourself somewhere else in the room after an electric
shock, it will have been your own muscles that put you there.

Steady on Roderick! Now that's a wee bit pedantic.
Are you not happy with ellipsis? Otherwise we will have to sort out
things like:

Water does not satisfiy your thirst, it satisfies your body's thirst.

A car does not run on pertrol, a car's engine runs on petrol.

You do not watch television, you watch images on the tube of the
television.

PHEW!

Thank you for de-pedantifying that.


--
Pierre, mon ami. Jetez encore un Scientologiste
dans le baquet d'acide.

- from a posting in alt.religion.scientology titled
"France recommends dissolving Scientologists"

Alex Coleman writes:

On 06 May 2006, Roderick
wrote:

In article , Alex Coleman wrote:
I assume that this was mains voltage rather than EHT, otherwise
you probably wouldn't be around to tell the tale.

i thought that some posts to a very recent thread said that HT was
not actually so very dangerous but would throw you across a room
(the main danger being how you landed).

Electricity doesn't "throw you across a room", so if somebody's
description included this statement you know how much you can trust
the rest of it.

If you find yourself somewhere else in the room after an electric
shock, it will have been your own muscles that put you there.


Steady on Roderick! Now that's a wee bit pedantic.
Are you not happy with ellipsis? Otherwise we will have to sort out
things like:

Water does not satisfiy your thirst, it satisfies your body's thirst.

A car does not run on pertrol, a car's engine runs on petrol.

You do not watch television, you watch images on the tube of the
television.

No, the images and sound are usually a waste of time. Watching the
electronics is more educational.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

In article , Alex Coleman wrote:
If you find yourself somewhere else in the room after an electric
shock, it will have been your own muscles that put you there.


Steady on Roderick! Now that's a wee bit pedantic.
Are you not happy with ellipsis?

Apologies if I underestimated you, but there are plenty of people who
apparently really believe that an electric shock will "throw you across
the room". I've no idea how they think it does this, and probably
neither have they, but they've heard it somewhere so it must be true
and will tenaciously defend this viewpoint against all attempts to
correct it.

Rod.

Chris Vowles LEASE
hath wroth:

Everything went fine with the picture changing until I moved around to
have a better look at the screen and the point of the screwdriver
slipped out of the pot and onto a live pin on the board ....
next thing I knew I was sat on the floor on the other side of the room
with a sore arm and a blackened screwdriver

Amazing. That was also one of my earlier introductions to electricity
when I was about 13 or 14 years old. I deduced that anything that
powerful was worth understanding.

I kinda miss the good old daze of tube radios and televisions. After
getting zapped a few times, one automatically developes a healthy
respect for high voltage. In the 2way radio business in the 1960's,
it was mostly tube radios. In Smog Angeles, we would kill off about 1
or 2 technicians each year, mostly from high voltage related
accidents. Darwin would be honored as the unworthy and careless
eliminated themselves.

My wakeup call was holding a cast zinc grounded microphone in one
hand, while probing around the high voltage cage with an NE-2 neon
lamp. The last thing I remember was a bright purple flash from the
NE-2 when I hit the plate cap.

I guess the only high voltage challenges left are CRT's, broadcasting,
and power transmission.

I did get an electrical engineering degree a few years later ......

Yep. I also managed to graduate college without getting killed or
drafted into the army. I even learned a few things along the way.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Roderick Stewart wrote:
In article , Alex Coleman wrote:

If you find yourself somewhere else in the room after an electric
shock, it will have been your own muscles that put you there.



Steady on Roderick! Now that's a wee bit pedantic.
Are you not happy with ellipsis?


Apologies if I underestimated you, but there are plenty of people who
apparently really believe that an electric shock will "throw you across
the room". I've no idea how they think it does this, and probably
neither have they, but they've heard it somewhere so it must be true
and will tenaciously defend this viewpoint against all attempts to
correct it.

Rod.


I have to explain that one to apprentices all the time. What throws you
across the room is your own muscles. When an electric shock causes all
of them to contract the stronger ones win the argument and their violent
contracting does the rest. If the shock does not kill you your own body
might throw you off a ladder or into a higher energy shock.

Yes I know that many of you new that but for those that didn't...
--
Tom of the sparks and arcs

"This alternating current thing is just a fad. It is much too dangerous
for general use." Thomas Alva Edison

On Tue, 02 May 2006 23:15:22 +0100, Roderick Stewart
wrote:


Greater susceptibility to noise on received sugnals, which would cause
raggedness of vertical lines due to variations in line timing. There's a
reason for using what was called "flywheel sync". A shorter time constant
effectively made it work with a smaller "flywheel" - OK for clean locally
generated video signals, but not good for off-air material.


I've only just realised reading this that it's *years* since I saw
ignition interference on my TV, there was a time when everything from
an electric razor upwards could flatten the received signal.

DG