When I was recently into the back of my Sony KV-27EXR15 set, I saw
some warnings about X-ray radiation exposure. Is there significant
exposure hazard while working on the set from the back? Since the
enclosure is entirely plastic, I would think that you'd be exposed to
x-rays no matter where you were located in relationship to the set,
not just when you opened the back to have a look.

Any comments?

Properly operating the risk is minimal, there are protect circuts within the
set which protect from over voltage and over current which, in design, shut
down the set.
"Darmok" wrote in message
...
When I was recently into the back of my Sony KV-27EXR15 set, I saw
some warnings about X-ray radiation exposure. Is there significant
exposure hazard while working on the set from the back? Since the
enclosure is entirely plastic, I would think that you'd be exposed to
x-rays no matter where you were located in relationship to the set,
not just when you opened the back to have a look.

Any comments?

"Art" writes:

Properly operating the risk is minimal, there are protect circuts within the
set which protect from over voltage and over current which, in design, shut
down the set.

Also keep in mind that the same warnings are on 1/2 inch camcorder
viewfinder CRTs.

And, as noted, the plastic won't block the X-rays so it's not much different
than with the back on.

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Just a quick FYI. The KV sets the energy level of the x-ray and the
current sets the quantity of x-rays produced. 25KV is right at the
threshold for x-ray generation capability of any significant level.
Hence the critical nature of the x-ray protect circuits.

The energy level would indicate how thick of an xray stopping material
would be required to protect you. At 25KV the lead in the glass is
enough to stop virtually all errant x-rays produced. The mA is the
amount of electrons flowing and the greater the electrons hitting the
surface, the greater the quantity of x-rays.

The dosimeters only measure the exposure to the quantity of x-rays, but
not the energy level. The higher the energy level the greater the
chance of causing a DNA mutation. The higher the dose over time, the
greater the chance of causing a DNA mutation.

In article .com,
wrote:

Just a quick FYI. The KV sets the energy level of the x-ray and the
current sets the quantity of x-rays produced. 25KV is right at the
threshold for x-ray generation capability of any significant level.
Hence the critical nature of the x-ray protect circuits.

Unless you've got a set like my old CTC-7, where the X ray protection
circuitry is just that the darn thing can't make the full 25kv most of
the time

Mine's got a 21FBP22 in it. I can't imnagine what the 21CYP22s were
like, . since this one's a rare earth. Reds so red they're orange...

Oh yeah, the remote acts funny. Yep, 4 function (on/off/mute/channel).
Sometimes just goes bonkers on its own accord. Thankfully, you can turn
it off...

It certainly used to be a real problem in the old days, when a PD500 shunt
regulator valve ( tube ) was used in the EHT supply. When working with the
deflection stage cage open, a lead glass shield had to be placed over this
device.

X Rays are easily created by accelerating a stream of electrons, and
slamming them into some kind of anode, and the 25 kV used in a CTV is plenty
enough to generate an electron beam with enough energy to do just this.

However, the electron beam should not actually ever touch the anode inside
the picture tube - otherwise no electrons would ever reach the faceplate to
light up the phosphor. The electrons do, however, dissipate large amounts of
their energy, when they collide with the slotmask inside the CRT. As far as
I know, this manifests as heat, but possibly, some soft x rays may be
generated. You are right that any generated to the rear or sides would
probably escape through the plastic cabinet, but the inside of this, or even
the plastic itself, may be treated to prevent EM radiation of all
wavelengths, as there is paranoia these days about such things.

I don't think that there is any significant danger from x rays any more from
CTVs. I would guess that as there is high voltage present, and high energy
electron beams present, the manufacturers err on the side of caution and
warn of the possibility of random x ray generation. As an addition, no x
rays would escape from the picture tube faceplate, as this is made from lead
doped glass to be sufficiently conductive to form the return path for the
spent electrons.

Geoff


"Darmok" wrote in message
...
When I was recently into the back of my Sony KV-27EXR15 set, I saw
some warnings about X-ray radiation exposure. Is there significant
exposure hazard while working on the set from the back? Since the
enclosure is entirely plastic, I would think that you'd be exposed to
x-rays no matter where you were located in relationship to the set,
not just when you opened the back to have a look.

Any comments?

On Wed, 15 Jun 2005 06:18:13 -0400, Darmok
wrote:

When I was recently into the back of my Sony KV-27EXR15 set, I saw
some warnings about X-ray radiation exposure. Is there significant
exposure hazard while working on the set from the back? Since the
enclosure is entirely plastic, I would think that you'd be exposed to
x-rays no matter where you were located in relationship to the set,
not just when you opened the back to have a look.

Most television sets are designed to be watched from the
frontside.
And in case someone forgets, there is that warning on the back.

But in practice: if you work on a life color-tv, X-ray radiation
is probably the least of your worries.

--
Kind regards,
Gerard Bok

"Darmok" wrote in message
...

When I was recently into the back of my Sony KV-27EXR15 set, I saw
some warnings about X-ray radiation exposure. Is there significant
exposure hazard while working on the set from the back? Since the
enclosure is entirely plastic, I would think that you'd be exposed to
x-rays no matter where you were located in relationship to the set,
not just when you opened the back to have a look.

There is a slight danger from X-Rays. There is also a slight danger from
repairing the set while in a swimming pool. Tobacco smoking is a REAL
danger.

N

Thanks for all the input. I guess, for the person who only looks into
the back of an operating TV once or twice a year, the hazard is
minimal. However, if my job were to be looking into the back end of
operating color TVs all day long, day after day, year after year, that
might be a different story. I wonder if there are any full-time TV
servicemen (women) who follow this NG who could give their input?

Cheers

I've been in the business 27 yrs, back in the old days of tube sets,
and early solid state there was no safety protection. Anybody remember
the old Zenith 20Y1C50 type set with a bad VDR? The HV would run
35-40KV all day, people happily watching their TV didn't know or care
the HV was too high and never hurt a thing, or the old Zenith 25EC
chassis with the bad safety capacitor that would let the high voltage
climb so high it would cut the neck off the picture tube? Never hurt
anyone that I know of. Sure never worried me then or now.

Darmok wrote:
Thanks for all the input. I guess, for the person who only looks into
the back of an operating TV once or twice a year, the hazard is
minimal. However, if my job were to be looking into the back end of
operating color TVs all day long, day after day, year after year, that
might be a different story. I wonder if there are any full-time TV
servicemen (women) who follow this NG who could give their input?

Cheers

On 15 Jun 2005 20:31:42 -0700, "RonKZ650" wrote:

I've been in the business 27 yrs, back in the old days of tube sets,
and early solid state there was no safety protection. Anybody remember
the old Zenith 20Y1C50 type set with a bad VDR? The HV would run
35-40KV all day, people happily watching their TV didn't know or care
the HV was too high and never hurt a thing, or the old Zenith 25EC
chassis with the bad safety capacitor that would let the high voltage
climb so high it would cut the neck off the picture tube? Never hurt
anyone that I know of. Sure never worried me then or now.


Thanks for your input!


Darmok wrote:
Thanks for all the input. I guess, for the person who only looks into
the back of an operating TV once or twice a year, the hazard is
minimal. However, if my job were to be looking into the back end of
operating color TVs all day long, day after day, year after year, that
might be a different story. I wonder if there are any full-time TV
servicemen (women) who follow this NG who could give their input?

Cheers

"RonKZ650" writes:

I've been in the business 27 yrs, back in the old days of tube sets,
and early solid state there was no safety protection. Anybody remember
the old Zenith 20Y1C50 type set with a bad VDR? The HV would run
35-40KV all day, people happily watching their TV didn't know or care
the HV was too high and never hurt a thing, or the old Zenith 25EC
chassis with the bad safety capacitor that would let the high voltage
climb so high it would cut the neck off the picture tube? Never hurt
anyone that I know of. Sure never worried me then or now.

How exactly would you know if it hurt anyone? It's not like you would
glow in the dark. Cancers can appear decades later....

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
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Ditto: same question.
You do not know if xrays injured you, unless it was prolonged exposure
of minutes or hours to an extremely high dose where you will have xray
burns.

Cancer and DNA damage may not show up for years later.

"Sam Goldwasser" wrote in message
...

How exactly would you know if it hurt anyone? It's not like you would
glow in the dark. Cancers can appear decades later....

You're not supposed to glow in the dark? Oh crap!

N

NSM wrote:

"Sam Goldwasser" wrote in message
...


How exactly would you know if it hurt anyone? It's not like you would
glow in the dark. Cancers can appear decades later....


You're not supposed to glow in the dark? Oh crap!

N

Send your application to Jeff Probst for the next Survivor.
Outwit, outplay, outglow

Ken

"Darmok" wrote in message
...
When I was recently into the back of my Sony KV-27EXR15 set, I saw
some warnings about X-ray radiation exposure. Is there significant
exposure hazard while working on the set from the back? Since the
enclosure is entirely plastic, I would think that you'd be exposed to
x-rays no matter where you were located in relationship to the set,
not just when you opened the back to have a look.

Any comments?


On a modern TV, zero risk, I've seen people *try* to make Xrays with a TV
CRT and have very little success, there's just too much lead in the glass.

"James Sweet" wrote in message
news:mHqse.15960$L65.7495@trnddc05...

On a modern TV, zero risk, I've seen people *try* to make Xrays with a TV
CRT and have very little success, there's just too much lead in the glass.

Better to look at "The Amateur Scientist" in "Scientific American". I'm sure
they have had a do it yourself X-Ray generator.

N

"NSM" writes:

"James Sweet" wrote in message
news:mHqse.15960$L65.7495@trnddc05...

On a modern TV, zero risk, I've seen people *try* to make Xrays with a TV
CRT and have very little success, there's just too much lead in the glass.

Better to look at "The Amateur Scientist" in "Scientific American". I'm sure
they have had a do it yourself X-Ray generator.

Typically they use an old high voltage rectifier tube. Never heard of
using a CRT.

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Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
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"Sam Goldwasser" wrote in message
...
"NSM" writes:

Typically they use an old high voltage rectifier tube. Never heard of
using a CRT.

That's my recollection too.

N

"Sam Goldwasser" wrote in message
...
"NSM" writes:

"James Sweet" wrote in message
news:mHqse.15960$L65.7495@trnddc05...

On a modern TV, zero risk, I've seen people *try* to make Xrays with a
TV
CRT and have very little success, there's just too much lead in the
glass.

Better to look at "The Amateur Scientist" in "Scientific American". I'm
sure
they have had a do it yourself X-Ray generator.

Typically they use an old high voltage rectifier tube. Never heard of
using a CRT.



It was more of an experiment just to see if Xrays could be produced with a
CRT, as I recall about all it did was melt a big hole in the shadow mask.

On Sat, 18 Jun 2005 01:27:01 GMT, "James Sweet"
wrote:


"Sam Goldwasser" wrote in message
...
"NSM" writes:

"James Sweet" wrote in message
news:mHqse.15960$L65.7495@trnddc05...

On a modern TV, zero risk, I've seen people *try* to make Xrays with a
TV
CRT and have very little success, there's just too much lead in the
glass.

Better to look at "The Amateur Scientist" in "Scientific American". I'm
sure
they have had a do it yourself X-Ray generator.

Typically they use an old high voltage rectifier tube. Never heard of
using a CRT.



It was more of an experiment just to see if Xrays could be produced with a
CRT, as I recall about all it did was melt a big hole in the shadow mask.


Okay, so I can see that the majority are clearly of a mind that xrays
cannot pass through the heavily leaded front of the picture tube.
What about the thin, transparent neck in the back of the tube?
Nothing much offering protection there, is there?

Just some comments for the history of the problem

The original X-Ray problem was found in some GE color tube sets that used a
triode
as a high voltage shunt regulator.

As long as the shunt was working properly there was no significant X-Ray
production and the triode was designed to contain the very low KV (soft)
X-Rays it did produce.

It was found that there was a failure mode that allowed the HV to rise and
the increased voltage was enough to generate a stronger (harder) X-Ray that
could exit the shunt tube.

As I recall the most intense area was directed down through the bottom of
the case. One of the comments about it's danger was that the most likely
person to receive significant exposure was the bar tender standing under a
wall mounted set.

I was part of a radiation safety team that inspected a GE plant in Illinois
that produced this chassie in the middle 1960s. As I recall there was no
recommendations for any changes to the production line at the plant to
reduce the exposure levels as there was not a level of radiation present
that required it.

A set was badly misadjusted for us to make some measurements that confirmed
the exposure levels.

Hugh
retired Nuke Safety Geek


----- Original Message -----
From: "Sam Goldwasser"
Newsgroups: sci.electronics.repair
Sent: Friday, June 17, 2005 7:02 AM
Subject: X-ray danger whilst working on TV?


"NSM" writes:

"James Sweet" wrote in message
news:mHqse.15960$L65.7495@trnddc05...

On a modern TV, zero risk, I've seen people *try* to make Xrays with a
TV
CRT and have very little success, there's just too much lead in the
glass.

Better to look at "The Amateur Scientist" in "Scientific American". I'm
sure
they have had a do it yourself X-Ray generator.

Typically they use an old high voltage rectifier tube. Never heard of
using a CRT.

--- sam | Sci.Electronics.Repair FAQ Mirror:
http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ:
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is
ignored unless my full name is included in the subject line. Or, you can
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"Sam Goldwasser" wrote in message
...
"NSM" writes:

"James Sweet" wrote in message
news:mHqse.15960$L65.7495@trnddc05...

On a modern TV, zero risk, I've seen people *try* to make Xrays with a
TV
CRT and have very little success, there's just too much lead in the
glass.

Better to look at "The Amateur Scientist" in "Scientific American". I'm
sure
they have had a do it yourself X-Ray generator.

Typically they use an old high voltage rectifier tube. Never heard of
using a CRT.

--- sam | Sci.Electronics.Repair FAQ Mirror:
http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ:
http://repairfaq.ece.drexel.edu/sam/lasersam.htm
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is
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