Bleeding LCD displays

[Cydrome Leader]

Cydrome Leader <presence@mungepanix.com> wrote:

Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lf2unn$lr7$1@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"N_Cook" <diverse@tcp.co.uk> wrote in message
news:levn39$ubr$1@dont-email.me...
On 02/03/2014 15:41, Rich Webb wrote:
On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook <diverse@tcp.co.uk> wrote:

Cause and any amelioration, short of draining the liquid and starting
again (for elfin safety in nothing else), and of course unobtanium
replacement displays

Where I used to work a batch of early large LCD display Philips DVM
meters for the engineers.
Every now and then , despite warning labels, someone would leave one
in
direct sunlight (UK version)

heh

for a while and the display would become
next to useless, permanently.
Presumably the LC migrates out of its assigned wells and does not go
back in them. Anyone know of a localised heat/cold/pressure treatment
or
something like that ,at least, won't make matters worse , and may
actually improve the splodge a bit?

That's been a problem with older LCD displays on Fluke DMMs as well.
My old 8050A is starting to exhibit those symptoms, despite having
been indoors all of its life.

It's ameliorated somewhat on mine when the display is energized for a
few hours; the dark areas retreat and become somewhat dimmer. Not a
permanent solution, but you might try that. Hook one up to an external
supply (they are battery powered?) and let it run over a weekend to
see if there's any improvement.

There are several hacks around the 'net where folks have replaced the
LCD module with a bank of 7-segment LEDs. What I'll probably try is to
fit an EADog 1x8 LCD module in place of the original, with a small
micro to handle the display initialization and character translation.
The EADog is 55 x 31 x 2 mm, a good fit for the 8050A.


This display is actually on a CD unit. Its not been used for some time
so
may be what you say. Its also on the lower part of the display, perhaps
turning the CD upside down,

Once I repaired TVs for a back street bodger - a CTV came in with a
rainbow
pattern on the picture and no amount of degaussing did any good. For some
reason I up-ended the TV, the picture improved a lot, so I turned it
completely upside down and the picture was perfect.

We took the CRT out and put it back upside down, then slackend the yoke
clamp and rotated that 180 deg, the purity rings needed a tweak but all
was
well - so we wedged a lino tile between the anode cap and PCB to stop it
cracking over, and cased it up.

That reminds me of when people actually rebuilt or replaced picture tubes.
Any good stories of tubes imploding?

I always made the scrap ones safe by knocking the neck off.

I'm aware of one guy that broke a neck off, by accident at a shop, but
nothing past that.

I've got to check you tube for vidoes of people removing the steel band
around a CRT. Not sure how you'd even weasel under one to cut it off, and
from a safe distance, but somebody somewhere has to have tried.

so it seems the bands are shrink fit into place, and expanded with heat:

http://www.patents.com/us-5241393.html

pickax to a CRT, indoors. safety equipment is an old blanket:

http://www.youtube.com/watch?v=m04XfekeSP4

brick? to a weird "wide" CRT.

http://www.youtube.com/watch?v=_0cXW7KQIDQ

another stupid one, from the same clever folks:

http://www.youtube.com/watch?v=Hx79zJO4zgA

 

[Phil Hobbs]

On 03/04/2014 11:40 AM, Cydrome Leader wrote:

Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lf2unn$lr7$1@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"N_Cook" <diverse@tcp.co.uk> wrote in message
news:levn39$ubr$1@dont-email.me...
On 02/03/2014 15:41, Rich Webb wrote:
On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook <diverse@tcp.co.uk> wrote:

Cause and any amelioration, short of draining the liquid and starting
again (for elfin safety in nothing else), and of course unobtanium
replacement displays

Where I used to work a batch of early large LCD display Philips DVM
meters for the engineers.
Every now and then , despite warning labels, someone would leave one
in
direct sunlight (UK version)

heh

for a while and the display would become
next to useless, permanently.
Presumably the LC migrates out of its assigned wells and does not go
back in them. Anyone know of a localised heat/cold/pressure treatment
or
something like that ,at least, won't make matters worse , and may
actually improve the splodge a bit?

That's been a problem with older LCD displays on Fluke DMMs as well.
My old 8050A is starting to exhibit those symptoms, despite having
been indoors all of its life.

It's ameliorated somewhat on mine when the display is energized for a
few hours; the dark areas retreat and become somewhat dimmer. Not a
permanent solution, but you might try that. Hook one up to an external
supply (they are battery powered?) and let it run over a weekend to
see if there's any improvement.

There are several hacks around the 'net where folks have replaced the
LCD module with a bank of 7-segment LEDs. What I'll probably try is to
fit an EADog 1x8 LCD module in place of the original, with a small
micro to handle the display initialization and character translation.
The EADog is 55 x 31 x 2 mm, a good fit for the 8050A.


This display is actually on a CD unit. Its not been used for some time
so
may be what you say. Its also on the lower part of the display, perhaps
turning the CD upside down,

Once I repaired TVs for a back street bodger - a CTV came in with a
rainbow
pattern on the picture and no amount of degaussing did any good. For some
reason I up-ended the TV, the picture improved a lot, so I turned it
completely upside down and the picture was perfect.

We took the CRT out and put it back upside down, then slackend the yoke
clamp and rotated that 180 deg, the purity rings needed a tweak but all
was
well - so we wedged a lino tile between the anode cap and PCB to stop it
cracking over, and cased it up.

That reminds me of when people actually rebuilt or replaced picture tubes.
Any good stories of tubes imploding?

I always made the scrap ones safe by knocking the neck off.

I'm aware of one guy that broke a neck off, by accident at a shop, but
nothing past that.

I've got to check you tube for vidoes of people removing the steel band
around a CRT. Not sure how you'd even weasel under one to cut it off, and
from a safe distance, but somebody somewhere has to have tried.

When I was a kid, I used to get dead TVs and take them apart for the
components. To get rid of the picture tubes, I put them in a Rubbermaid
trash can and shot out the faceplate with my slingshot.

Great fun--glass _everywhere_.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Ian Field]

"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lf4vme$9id$2@reader1.panix.com...

Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lf2unn$lr7$1@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"N_Cook" <diverse@tcp.co.uk> wrote in message
news:levn39$ubr$1@dont-email.me...
On 02/03/2014 15:41, Rich Webb wrote:
On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook <diverse@tcp.co.uk> wrote:

Cause and any amelioration, short of draining the liquid and
starting
again (for elfin safety in nothing else), and of course unobtanium
replacement displays

Where I used to work a batch of early large LCD display Philips DVM
meters for the engineers.
Every now and then , despite warning labels, someone would leave one
in
direct sunlight (UK version)

heh

for a while and the display would become
next to useless, permanently.
Presumably the LC migrates out of its assigned wells and does not go
back in them. Anyone know of a localised heat/cold/pressure
treatment
or
something like that ,at least, won't make matters worse , and may
actually improve the splodge a bit?

That's been a problem with older LCD displays on Fluke DMMs as well.
My old 8050A is starting to exhibit those symptoms, despite having
been indoors all of its life.

It's ameliorated somewhat on mine when the display is energized for a
few hours; the dark areas retreat and become somewhat dimmer. Not a
permanent solution, but you might try that. Hook one up to an
external
supply (they are battery powered?) and let it run over a weekend to
see if there's any improvement.

There are several hacks around the 'net where folks have replaced the
LCD module with a bank of 7-segment LEDs. What I'll probably try is
to
fit an EADog 1x8 LCD module in place of the original, with a small
micro to handle the display initialization and character translation.
The EADog is 55 x 31 x 2 mm, a good fit for the 8050A.


This display is actually on a CD unit. Its not been used for some time
so
may be what you say. Its also on the lower part of the display,
perhaps
turning the CD upside down,

Once I repaired TVs for a back street bodger - a CTV came in with a
rainbow
pattern on the picture and no amount of degaussing did any good. For
some
reason I up-ended the TV, the picture improved a lot, so I turned it
completely upside down and the picture was perfect.

We took the CRT out and put it back upside down, then slackend the yoke
clamp and rotated that 180 deg, the purity rings needed a tweak but all
was
well - so we wedged a lino tile between the anode cap and PCB to stop
it
cracking over, and cased it up.

That reminds me of when people actually rebuilt or replaced picture
tubes.
Any good stories of tubes imploding?

I always made the scrap ones safe by knocking the neck off.

I'm aware of one guy that broke a neck off, by accident at a shop, but
nothing past that.

I've got to check you tube for vidoes of people removing the steel band
around a CRT. Not sure how you'd even weasel under one to cut it off, and
from a safe distance, but somebody somewhere has to have tried.

Years ago I used to visit the local tip to pick up TVs to refurbish, once I
found a set that I only wanted the PCB from, so the quickest way to remove
the wooden cabinet and all the other unwanted stuff was with my steel toecap
boot - during this procedure, the faceplate fell off the CRT - its literally
only glued on!

On another occasion someone I knew was minding the site while the regular
bloke was away, I persuaded him to slowly advance the hydraulic ram in the
compactor while I nipped a CRT diagonally across 2 corners between the ram
and the opening in the container. Once I was safely out of the chute we
switched the ram back on, the hydraulics did a great deal of heaving and
grunting - meanwhile some bloke had gone up the steps to tip his rubbish,
suddenly there was an almighty bang, the ground shook and the bloke was
enveloped by a silver blizzard that used to be the metalisation inside the
tube.

I've seen photos online of the aftermath of an implosion on a CRT production
line - apparently its possible for one imploding CRT to set off a chain
reaction that destroys quite a few.

 

[Jeff Liebermann]

On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook <diverse@tcp.co.uk> wrote:

Cause and any amelioration, short of draining the liquid and starting
again (for elfin safety in nothing else), and of course unobtanium
replacement displays

Where I used to work a batch of early large LCD display Philips DVM
meters for the engineers.
Every now and then , despite warning labels, someone would leave one in
direct sunlight (UK version) for a while and the display would become
next to useless, permanently.
Presumably the LC migrates out of its assigned wells and does not go
back in them. Anyone know of a localised heat/cold/pressure treatment or
something like that ,at least, won't make matters worse , and may
actually improve the splodge a bit?

LCD panels have a slots at the bottom of the glass to help equalize
inside to outside air pressure. If it were sealed shut, your laptop
or tablet display would explode at altitude.

One of my non-clever mistakes is to clean the screen of a warm running
laptop display with a soapy water while in the upright position. As
the screen cools, the soapy water is sucked into the panel via the
bottom slots. Eventually, LCD leprosy forms along the bottom of the
display. I have several panels like that, all from an office where
the cleaning service washed down the LCD displays every night as part
of the service.

I would speculate (which means I haven't tried doing this) that it
would be possible to use the partial vacuum effect to replenish the
liquid in the display. I have no idea what's in the liquid or where
to obtain a supply. Just remove the lower part of the panel frame,
heat the panel, dump into some warm LCD liquid, and hope that it sucks
the liquid into the panel as it cools. LCD Panel Rejuvenator (patent
pending).

The LCD panel manufactures could probably prevent the problem by
simply adding a foam sponge along the slot to act as a reservoir.

Incidentally, the fluid is reputed to be sticky and toxic.

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

 

[Leif Neland]

Fřlgende er skrevet af Phil Hobbs:

When I was a kid, I used to get dead TVs and take them apart for the
components. To get rid of the picture tubes, I put them in a Rubbermaid
trash can and shot out the faceplate with my slingshot.

As a kid I unwrapped the capacitors to find the interesting stuff
inside all that wrapping paper. Never found anything, though...

Leif


--
Husk křrelys bagpĺ, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.

 

[Cydrome Leader]

Ian Field <gangprobing.alien@ntlworld.com> wrote:

"Leif Neland" <leif@neland.dk> wrote in message
news:mn.25717de3c4382915.130671@neland.dk...
F?lgende er skrevet af Phil Hobbs:

When I was a kid, I used to get dead TVs and take them apart for the
components. To get rid of the picture tubes, I put them in a Rubbermaid
trash can and shot out the faceplate with my slingshot.

As a kid I unwrapped the capacitors to find the interesting stuff inside
all that wrapping paper. Never found anything, though...

When I was a kid, someone gave me a regen set in a very grand wooden
cabinet.

When I'd finished breaking it - it was time to take it apart and see what's
in it.

In a compartment under the one the chassis was in, there was a huge flat
profile paper capacitor - one that big could only have been the HT
reservoir.

Think of all the things I could've got up to with that if I hadn't unraveled
it!

I dragged a huge transformer out of a TV set to grade school once to show
people the huge sparks that could be drawn off one winding with a 9 volt
battery. It was actually a fairly fat and impressive arc. The transformer
was eventually confiscated. Boo.

 

[Ian Field]

"Leif Neland" <leif@neland.dk> wrote in message
news:mn.25717de3c4382915.130671@neland.dk...

Fřlgende er skrevet af Phil Hobbs:

When I was a kid, I used to get dead TVs and take them apart for the
components. To get rid of the picture tubes, I put them in a Rubbermaid
trash can and shot out the faceplate with my slingshot.

As a kid I unwrapped the capacitors to find the interesting stuff inside
all that wrapping paper. Never found anything, though...

When I was a kid, someone gave me a regen set in a very grand wooden
cabinet.

When I'd finished breaking it - it was time to take it apart and see what's
in it.

In a compartment under the one the chassis was in, there was a huge flat
profile paper capacitor - one that big could only have been the HT
reservoir.

Think of all the things I could've got up to with that if I hadn't unraveled
it!

 

[Ian Field]

"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lf88g1$gsq$2@reader1.panix.com...

Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Leif Neland" <leif@neland.dk> wrote in message
news:mn.25717de3c4382915.130671@neland.dk...
F?lgende er skrevet af Phil Hobbs:

When I was a kid, I used to get dead TVs and take them apart for the
components. To get rid of the picture tubes, I put them in a
Rubbermaid
trash can and shot out the faceplate with my slingshot.

As a kid I unwrapped the capacitors to find the interesting stuff inside
all that wrapping paper. Never found anything, though...

When I was a kid, someone gave me a regen set in a very grand wooden
cabinet.

When I'd finished breaking it - it was time to take it apart and see
what's
in it.

In a compartment under the one the chassis was in, there was a huge flat
profile paper capacitor - one that big could only have been the HT
reservoir.

Think of all the things I could've got up to with that if I hadn't
unraveled
it!

I dragged a huge transformer out of a TV set to grade school once to show
people the huge sparks that could be drawn off one winding with a 9 volt
battery. It was actually a fairly fat and impressive arc. The transformer
was eventually confiscated. Boo.

Those old mains derived EHT transformers were probably even more lethal than
a MO transformer.

For a B&W TV, 6 - 7kV was about average - not sure whether any CTV ever had
mains derived EHT.

 

[Cydrome Leader]

Ian Field <gangprobing.alien@ntlworld.com> wrote:

"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lf88g1$gsq$2@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Leif Neland" <leif@neland.dk> wrote in message
news:mn.25717de3c4382915.130671@neland.dk...
F?lgende er skrevet af Phil Hobbs:

When I was a kid, I used to get dead TVs and take them apart for the
components. To get rid of the picture tubes, I put them in a
Rubbermaid
trash can and shot out the faceplate with my slingshot.

As a kid I unwrapped the capacitors to find the interesting stuff inside
all that wrapping paper. Never found anything, though...

When I was a kid, someone gave me a regen set in a very grand wooden
cabinet.

When I'd finished breaking it - it was time to take it apart and see
what's
in it.

In a compartment under the one the chassis was in, there was a huge flat
profile paper capacitor - one that big could only have been the HT
reservoir.

Think of all the things I could've got up to with that if I hadn't
unraveled
it!

I dragged a huge transformer out of a TV set to grade school once to show
people the huge sparks that could be drawn off one winding with a 9 volt
battery. It was actually a fairly fat and impressive arc. The transformer
was eventually confiscated. Boo.

Those old mains derived EHT transformers were probably even more lethal than
a MO transformer.

For a B&W TV, 6 - 7kV was about average - not sure whether any CTV ever had
mains derived EHT.

It was some sort of large gooped up with tar EI core thingy with one super
high inductance winding. I still have no idea how it worked in a
television. If they made 6-7kv was there then some sort of diode and cap
multiplier to run the CRT?

The "oldest" TVs I sort of recall the inside of were Zenith consoles with
remanufactured module system with the bizarro rectangular connectors and
constantly changing color circuit boards.

 

[Cydrome Leader]

Jeff Liebermann <jeffl@cruzio.com> wrote:

On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook <diverse@tcp.co.uk> wrote:

Cause and any amelioration, short of draining the liquid and starting
again (for elfin safety in nothing else), and of course unobtanium
replacement displays

Where I used to work a batch of early large LCD display Philips DVM
meters for the engineers.
Every now and then , despite warning labels, someone would leave one in
direct sunlight (UK version) for a while and the display would become
next to useless, permanently.
Presumably the LC migrates out of its assigned wells and does not go
back in them. Anyone know of a localised heat/cold/pressure treatment or
something like that ,at least, won't make matters worse , and may
actually improve the splodge a bit?

LCD panels have a slots at the bottom of the glass to help equalize
inside to outside air pressure. If it were sealed shut, your laptop
or tablet display would explode at altitude.

One of my non-clever mistakes is to clean the screen of a warm running
laptop display with a soapy water while in the upright position. As
the screen cools, the soapy water is sucked into the panel via the
bottom slots. Eventually, LCD leprosy forms along the bottom of the
display. I have several panels like that, all from an office where
the cleaning service washed down the LCD displays every night as part
of the service.

I would speculate (which means I haven't tried doing this) that it
would be possible to use the partial vacuum effect to replenish the
liquid in the display. I have no idea what's in the liquid or where
to obtain a supply. Just remove the lower part of the panel frame,
heat the panel, dump into some warm LCD liquid, and hope that it sucks
the liquid into the panel as it cools. LCD Panel Rejuvenator (patent
pending).

The LCD panel manufactures could probably prevent the problem by
simply adding a foam sponge along the slot to act as a reservoir.

Incidentally, the fluid is reputed to be sticky and toxic.

it's oily for sure, and busted open LCDs smell bad but that may be from
the 5000 layers of adhesive and plastic sheets that make them. Old
calculator displays were a bit simpler, but still had a foul smell when
smashed up.

 

[Cydrome Leader]

Ian Field <gangprobing.alien@ntlworld.com> wrote:

"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lfbil3$6ij$1@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lf88g1$gsq$2@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Leif Neland" <leif@neland.dk> wrote in message
news:mn.25717de3c4382915.130671@neland.dk...
F?lgende er skrevet af Phil Hobbs:

When I was a kid, I used to get dead TVs and take them apart for the
components. To get rid of the picture tubes, I put them in a
Rubbermaid
trash can and shot out the faceplate with my slingshot.

As a kid I unwrapped the capacitors to find the interesting stuff
inside
all that wrapping paper. Never found anything, though...

When I was a kid, someone gave me a regen set in a very grand wooden
cabinet.

When I'd finished breaking it - it was time to take it apart and see
what's
in it.

In a compartment under the one the chassis was in, there was a huge
flat
profile paper capacitor - one that big could only have been the HT
reservoir.

Think of all the things I could've got up to with that if I hadn't
unraveled
it!

I dragged a huge transformer out of a TV set to grade school once to
show
people the huge sparks that could be drawn off one winding with a 9 volt
battery. It was actually a fairly fat and impressive arc. The
transformer
was eventually confiscated. Boo.

Those old mains derived EHT transformers were probably even more lethal
than
a MO transformer.

For a B&W TV, 6 - 7kV was about average - not sure whether any CTV ever
had
mains derived EHT.

It was some sort of large gooped up with tar EI core thingy with one super
high inductance winding. I still have no idea how it worked in a
television. If they made 6-7kv was there then some sort of diode and cap
multiplier to run the CRT?

AFAIK it was just half-wave rectified, the peak value whatever that was,
ended up at the final anode.

Its a bit surprising when you think that generally, CRTs were long narrow
defection jobs - some early homebrew sets had electrostatic deflection,
maybe a few commercially produced sets too.

Is this why tubes like in oscilloscopes, which are electrocstatic are so
long for their screen size? My current scope doesn't have the hump in the
back for the end of the tube, but I suspect it's a normal CRT with a yoke
and coils as well, since it's really just a small computer monitor.

 

[Ian Field]

"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lfbil3$6ij$1@reader1.panix.com...

Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lf88g1$gsq$2@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Leif Neland" <leif@neland.dk> wrote in message
news:mn.25717de3c4382915.130671@neland.dk...
F?lgende er skrevet af Phil Hobbs:

When I was a kid, I used to get dead TVs and take them apart for the
components. To get rid of the picture tubes, I put them in a
Rubbermaid
trash can and shot out the faceplate with my slingshot.

As a kid I unwrapped the capacitors to find the interesting stuff
inside
all that wrapping paper. Never found anything, though...

When I was a kid, someone gave me a regen set in a very grand wooden
cabinet.

When I'd finished breaking it - it was time to take it apart and see
what's
in it.

In a compartment under the one the chassis was in, there was a huge
flat
profile paper capacitor - one that big could only have been the HT
reservoir.

Think of all the things I could've got up to with that if I hadn't
unraveled
it!

I dragged a huge transformer out of a TV set to grade school once to
show
people the huge sparks that could be drawn off one winding with a 9 volt
battery. It was actually a fairly fat and impressive arc. The
transformer
was eventually confiscated. Boo.

Those old mains derived EHT transformers were probably even more lethal
than
a MO transformer.

For a B&W TV, 6 - 7kV was about average - not sure whether any CTV ever
had
mains derived EHT.

It was some sort of large gooped up with tar EI core thingy with one super
high inductance winding. I still have no idea how it worked in a
television. If they made 6-7kv was there then some sort of diode and cap
multiplier to run the CRT?

AFAIK it was just half-wave rectified, the peak value whatever that was,
ended up at the final anode.

Its a bit surprising when you think that generally, CRTs were long narrow
defection jobs - some early homebrew sets had electrostatic deflection,
maybe a few commercially produced sets too.

 

[Phil Hobbs]

On 03/07/2014 03:13 PM, Cydrome Leader wrote:

Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lfbil3$6ij$1@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lf88g1$gsq$2@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Leif Neland" <leif@neland.dk> wrote in message
news:mn.25717de3c4382915.130671@neland.dk...
F?lgende er skrevet af Phil Hobbs:

When I was a kid, I used to get dead TVs and take them apart for the
components. To get rid of the picture tubes, I put them in a
Rubbermaid
trash can and shot out the faceplate with my slingshot.

As a kid I unwrapped the capacitors to find the interesting stuff
inside
all that wrapping paper. Never found anything, though...

When I was a kid, someone gave me a regen set in a very grand wooden
cabinet.

When I'd finished breaking it - it was time to take it apart and see
what's
in it.

In a compartment under the one the chassis was in, there was a huge
flat
profile paper capacitor - one that big could only have been the HT
reservoir.

Think of all the things I could've got up to with that if I hadn't
unraveled
it!

I dragged a huge transformer out of a TV set to grade school once to
show
people the huge sparks that could be drawn off one winding with a 9 volt
battery. It was actually a fairly fat and impressive arc. The
transformer
was eventually confiscated. Boo.

Those old mains derived EHT transformers were probably even more lethal
than
a MO transformer.

For a B&W TV, 6 - 7kV was about average - not sure whether any CTV ever
had
mains derived EHT.

It was some sort of large gooped up with tar EI core thingy with one super
high inductance winding. I still have no idea how it worked in a
television. If they made 6-7kv was there then some sort of diode and cap
multiplier to run the CRT?

AFAIK it was just half-wave rectified, the peak value whatever that was,
ended up at the final anode.

Its a bit surprising when you think that generally, CRTs were long narrow
defection jobs - some early homebrew sets had electrostatic deflection,
maybe a few commercially produced sets too.

Is this why tubes like in oscilloscopes, which are electrocstatic are so
long for their screen size? My current scope doesn't have the hump in the
back for the end of the tube, but I suspect it's a normal CRT with a yoke
and coils as well, since it's really just a small computer monitor.

Electrostatic focusing is much faster than magnetic, but not nearly so
well controlled--you get a lot of aberrations, which grow very rapidly
with deflection angle. The basic issue is that electrons that are closer
to the plate get bent further than those further away. In an optical
system, you can correct for this by using a combination of positive and
negative lenses, but there's no such thing as a negative electrostatic lens.

It was a real parlour trick getting decent vertical linearity and good
spot sizes with pure electrostatic deflection.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Ian Field]

"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
news:FOCdnX8T0NfD14fOnZ2dnUVZ_rCdnZ2d@supernews.com...

On 03/07/2014 03:13 PM, Cydrome Leader wrote:
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lfbil3$6ij$1@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lf88g1$gsq$2@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Leif Neland" <leif@neland.dk> wrote in message
news:mn.25717de3c4382915.130671@neland.dk...
F?lgende er skrevet af Phil Hobbs:

When I was a kid, I used to get dead TVs and take them apart for
the
components. To get rid of the picture tubes, I put them in a
Rubbermaid
trash can and shot out the faceplate with my slingshot.

As a kid I unwrapped the capacitors to find the interesting stuff
inside
all that wrapping paper. Never found anything, though...

When I was a kid, someone gave me a regen set in a very grand wooden
cabinet.

When I'd finished breaking it - it was time to take it apart and see
what's
in it.

In a compartment under the one the chassis was in, there was a huge
flat
profile paper capacitor - one that big could only have been the HT
reservoir.

Think of all the things I could've got up to with that if I hadn't
unraveled
it!

I dragged a huge transformer out of a TV set to grade school once to
show
people the huge sparks that could be drawn off one winding with a 9
volt
battery. It was actually a fairly fat and impressive arc. The
transformer
was eventually confiscated. Boo.

Those old mains derived EHT transformers were probably even more
lethal
than
a MO transformer.

For a B&W TV, 6 - 7kV was about average - not sure whether any CTV
ever
had
mains derived EHT.

It was some sort of large gooped up with tar EI core thingy with one
super
high inductance winding. I still have no idea how it worked in a
television. If they made 6-7kv was there then some sort of diode and
cap
multiplier to run the CRT?

AFAIK it was just half-wave rectified, the peak value whatever that was,
ended up at the final anode.

Its a bit surprising when you think that generally, CRTs were long
narrow
defection jobs - some early homebrew sets had electrostatic deflection,
maybe a few commercially produced sets too.

Is this why tubes like in oscilloscopes, which are electrocstatic are so
long for their screen size? My current scope doesn't have the hump in the
back for the end of the tube, but I suspect it's a normal CRT with a yoke
and coils as well, since it's really just a small computer monitor.


Electrostatic focusing is much faster than magnetic, but not nearly so
well controlled--you get a lot of aberrations, which grow very rapidly
with deflection angle. The basic issue is that electrons that are closer
to the plate get bent further than those further away. In an optical
system, you can correct for this by using a combination of positive and
negative lenses, but there's no such thing as a negative electrostatic
lens.

It was a real parlour trick getting decent vertical linearity and good
spot sizes with pure electrostatic deflection.

Speaking of optics - I remember a PC monitor with a slightly concave
faceplate, that was a pretty substantial slab of glass, the things weighed a
bloody ton!

Most of the components were house coded so it was frequently neccessary to
board-swap from the growing accumulation of scrap units.

 

[Cydrome Leader]

Ian Field <gangprobing.alien@ntlworld.com> wrote:

"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
news:FOCdnX8T0NfD14fOnZ2dnUVZ_rCdnZ2d@supernews.com...
On 03/07/2014 03:13 PM, Cydrome Leader wrote:
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lfbil3$6ij$1@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lf88g1$gsq$2@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Leif Neland" <leif@neland.dk> wrote in message
news:mn.25717de3c4382915.130671@neland.dk...
F?lgende er skrevet af Phil Hobbs:

When I was a kid, I used to get dead TVs and take them apart for
the
components. To get rid of the picture tubes, I put them in a
Rubbermaid
trash can and shot out the faceplate with my slingshot.

As a kid I unwrapped the capacitors to find the interesting stuff
inside
all that wrapping paper. Never found anything, though...

When I was a kid, someone gave me a regen set in a very grand wooden
cabinet.

When I'd finished breaking it - it was time to take it apart and see
what's
in it.

In a compartment under the one the chassis was in, there was a huge
flat
profile paper capacitor - one that big could only have been the HT
reservoir.

Think of all the things I could've got up to with that if I hadn't
unraveled
it!

I dragged a huge transformer out of a TV set to grade school once to
show
people the huge sparks that could be drawn off one winding with a 9
volt
battery. It was actually a fairly fat and impressive arc. The
transformer
was eventually confiscated. Boo.

Those old mains derived EHT transformers were probably even more
lethal
than
a MO transformer.

For a B&W TV, 6 - 7kV was about average - not sure whether any CTV
ever
had
mains derived EHT.

It was some sort of large gooped up with tar EI core thingy with one
super
high inductance winding. I still have no idea how it worked in a
television. If they made 6-7kv was there then some sort of diode and
cap
multiplier to run the CRT?

AFAIK it was just half-wave rectified, the peak value whatever that was,
ended up at the final anode.

Its a bit surprising when you think that generally, CRTs were long
narrow
defection jobs - some early homebrew sets had electrostatic deflection,
maybe a few commercially produced sets too.

Is this why tubes like in oscilloscopes, which are electrocstatic are so
long for their screen size? My current scope doesn't have the hump in the
back for the end of the tube, but I suspect it's a normal CRT with a yoke
and coils as well, since it's really just a small computer monitor.


Electrostatic focusing is much faster than magnetic, but not nearly so
well controlled--you get a lot of aberrations, which grow very rapidly
with deflection angle. The basic issue is that electrons that are closer
to the plate get bent further than those further away. In an optical
system, you can correct for this by using a combination of positive and
negative lenses, but there's no such thing as a negative electrostatic
lens.

It was a real parlour trick getting decent vertical linearity and good
spot sizes with pure electrostatic deflection.

Speaking of optics - I remember a PC monitor with a slightly concave
faceplate, that was a pretty substantial slab of glass, the things weighed a
bloody ton!

Was it possibly one of those Zenith flat CRTs that really did look
concave? They were really weird looking, powered on or off.

 

[William Sommerwerck]

"Cydrome Leader" wrote in message news:lfgtev$kci$2@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:

Speaking of optics - I remember a PC monitor with a slightly
concave faceplate, that was a pretty substantial slab of glass,
the things weighed a bloody ton!

Was it possibly one of those Zenith flat CRTs that really did look
concave? They were really weird looking, powered on or off.

Zernith made a 14" CRT for computer monitors with a flat face, anticipating
Sony by about a decade. (The phosphors were laid down without the mask. The
tolerances were so tight, that any mask would work with any faceplate, simply
be dropping it into place.) Someone at work had one, and it did, indeed, look
odd.

Sony compensated for that optical illusion with a faintly bulging screen. I
have one of the 400-series WEGAs in my bedroom (it's been going strong since
2000), and you can see the bulge if you stand the screen and look downward.

 

[Ian Field]

"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lfgtev$kci$2@reader1.panix.com...

Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
news:FOCdnX8T0NfD14fOnZ2dnUVZ_rCdnZ2d@supernews.com...
On 03/07/2014 03:13 PM, Cydrome Leader wrote:
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lfbil3$6ij$1@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lf88g1$gsq$2@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:


"Leif Neland" <leif@neland.dk> wrote in message
news:mn.25717de3c4382915.130671@neland.dk...
F?lgende er skrevet af Phil Hobbs:

When I was a kid, I used to get dead TVs and take them apart for
the
components. To get rid of the picture tubes, I put them in a
Rubbermaid
trash can and shot out the faceplate with my slingshot.

As a kid I unwrapped the capacitors to find the interesting stuff
inside
all that wrapping paper. Never found anything, though...

When I was a kid, someone gave me a regen set in a very grand
wooden
cabinet.

When I'd finished breaking it - it was time to take it apart and
see
what's
in it.

In a compartment under the one the chassis was in, there was a
huge
flat
profile paper capacitor - one that big could only have been the HT
reservoir.

Think of all the things I could've got up to with that if I hadn't
unraveled
it!

I dragged a huge transformer out of a TV set to grade school once
to
show
people the huge sparks that could be drawn off one winding with a 9
volt
battery. It was actually a fairly fat and impressive arc. The
transformer
was eventually confiscated. Boo.

Those old mains derived EHT transformers were probably even more
lethal
than
a MO transformer.

For a B&W TV, 6 - 7kV was about average - not sure whether any CTV
ever
had
mains derived EHT.

It was some sort of large gooped up with tar EI core thingy with one
super
high inductance winding. I still have no idea how it worked in a
television. If they made 6-7kv was there then some sort of diode and
cap
multiplier to run the CRT?

AFAIK it was just half-wave rectified, the peak value whatever that
was,
ended up at the final anode.

Its a bit surprising when you think that generally, CRTs were long
narrow
defection jobs - some early homebrew sets had electrostatic
deflection,
maybe a few commercially produced sets too.

Is this why tubes like in oscilloscopes, which are electrocstatic are
so
long for their screen size? My current scope doesn't have the hump in
the
back for the end of the tube, but I suspect it's a normal CRT with a
yoke
and coils as well, since it's really just a small computer monitor.


Electrostatic focusing is much faster than magnetic, but not nearly so
well controlled--you get a lot of aberrations, which grow very rapidly
with deflection angle. The basic issue is that electrons that are closer
to the plate get bent further than those further away. In an optical
system, you can correct for this by using a combination of positive and
negative lenses, but there's no such thing as a negative electrostatic
lens.

It was a real parlour trick getting decent vertical linearity and good
spot sizes with pure electrostatic deflection.

Speaking of optics - I remember a PC monitor with a slightly concave
faceplate, that was a pretty substantial slab of glass, the things
weighed a
bloody ton!

Was it possibly one of those Zenith flat CRTs that really did look
concave? They were really weird looking, powered on or off.

Now you mention it I think they were zenith - there was a sort of flurry of
people wanting them repaired, then they dried up as if they'd never existed.

Not long after that, CRTs in general went out of fashion.

I didn't miss those flat screens - they were bloody heavy!

 

[Cydrome Leader]

William Sommerwerck <grizzledgeezer@comcast.net> wrote:

"Cydrome Leader" wrote in message news:lfgtev$kci$2@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:

Speaking of optics - I remember a PC monitor with a slightly
concave faceplate, that was a pretty substantial slab of glass,
the things weighed a bloody ton!

Was it possibly one of those Zenith flat CRTs that really did look
concave? They were really weird looking, powered on or off.

Zernith made a 14" CRT for computer monitors with a flat face, anticipating
Sony by about a decade. (The phosphors were laid down without the mask. The
tolerances were so tight, that any mask would work with any faceplate, simply
be dropping it into place.) Someone at work had one, and it did, indeed, look
odd.

Sony compensated for that optical illusion with a faintly bulging screen. I
have one of the 400-series WEGAs in my bedroom (it's been going strong since
2000), and you can see the bulge if you stand the screen and look downward.

The monitor wars from back then were amusing. Getting my first 15" monitor
was a big deal, and they even had strange stuff like 16" monitors (Nanao
made those). Quite a few of the Taiwanese computer monitors were actually
pretty good as well.

Once they really nailed good displays for computers, the cheap and crappy
LCDs flooded the market.

I'm typing up this message on a Dell badged Sony Trinitron made in Sep,
2000. The retrace lines are appearing so it's time for some new caps at
some point.

 

[Cydrome Leader]

Ian Field <gangprobing.alien@ntlworld.com> wrote:

"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lfkrh0$36i$2@reader1.panix.com...
William Sommerwerck <grizzledgeezer@comcast.net> wrote:
"Cydrome Leader" wrote in message news:lfgtev$kci$2@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:

Speaking of optics - I remember a PC monitor with a slightly
concave faceplate, that was a pretty substantial slab of glass,
the things weighed a bloody ton!

Was it possibly one of those Zenith flat CRTs that really did look
concave? They were really weird looking, powered on or off.

Zernith made a 14" CRT for computer monitors with a flat face,
anticipating
Sony by about a decade. (The phosphors were laid down without the mask.
The
tolerances were so tight, that any mask would work with any faceplate,
simply
be dropping it into place.) Someone at work had one, and it did, indeed,
look
odd.

Sony compensated for that optical illusion with a faintly bulging screen.
I
have one of the 400-series WEGAs in my bedroom (it's been going strong
since
2000), and you can see the bulge if you stand the screen and look
downward.

The monitor wars from back then were amusing. Getting my first 15" monitor
was a big deal, and they even had strange stuff like 16" monitors (Nanao
made those). Quite a few of the Taiwanese computer monitors were actually
pretty good as well.

Once they really nailed good displays for computers, the cheap and crappy
LCDs flooded the market.

I'm typing up this message on a Dell badged Sony Trinitron made in Sep,
2000. The retrace lines are appearing so it's time for some new caps at
some point.

Somewhere in the back of the garage I have about 8 CPD15s (some badged as
Dell).

Since finding an analogue LCD TV with a VGA socket on the back in the bin
room at the flats, the Sonys haven't got any nearer to being dragged inside
and repaired.

I can't bring myself to tossing my monitor mountain, and most still work
fine (that's why they are still here.)

 

[Ian Field]

"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:lfkrh0$36i$2@reader1.panix.com...

William Sommerwerck <grizzledgeezer@comcast.net> wrote:
"Cydrome Leader" wrote in message news:lfgtev$kci$2@reader1.panix.com...
Ian Field <gangprobing.alien@ntlworld.com> wrote:

Speaking of optics - I remember a PC monitor with a slightly
concave faceplate, that was a pretty substantial slab of glass,
the things weighed a bloody ton!

Was it possibly one of those Zenith flat CRTs that really did look
concave? They were really weird looking, powered on or off.

Zernith made a 14" CRT for computer monitors with a flat face,
anticipating
Sony by about a decade. (The phosphors were laid down without the mask.
The
tolerances were so tight, that any mask would work with any faceplate,
simply
be dropping it into place.) Someone at work had one, and it did, indeed,
look
odd.

Sony compensated for that optical illusion with a faintly bulging screen.
I
have one of the 400-series WEGAs in my bedroom (it's been going strong
since
2000), and you can see the bulge if you stand the screen and look
downward.

The monitor wars from back then were amusing. Getting my first 15" monitor
was a big deal, and they even had strange stuff like 16" monitors (Nanao
made those). Quite a few of the Taiwanese computer monitors were actually
pretty good as well.

Once they really nailed good displays for computers, the cheap and crappy
LCDs flooded the market.

I'm typing up this message on a Dell badged Sony Trinitron made in Sep,
2000. The retrace lines are appearing so it's time for some new caps at
some point.

Somewhere in the back of the garage I have about 8 CPD15s (some badged as
Dell).

Since finding an analogue LCD TV with a VGA socket on the back in the bin
room at the flats, the Sonys haven't got any nearer to being dragged inside
and repaired.