1 Jul
2016
1 Jul
'16
11:41 a.m.
I know a few list members who have been doing this, after fixing CRT
cataracts.
Was that glass additionally leaded to cut down on X-rays at all? Is there a
risk to that?
These are mostly black and white CRTs.
--
Ian Finder
(206) 395-MIPS
ian.finder at gmail.com
1 Jul
1 Jul
11:43 a.m.
On Jul 1, 2016, at 2:41 PM, Ian Finder <ian.finder
at gmail.com> wrote:
I know a few list members who have been doing this, after fixing CRT
cataracts.
Was that glass additionally leaded to cut down on X-rays at all? Is there a
risk to that?
These are mostly black and white CRTs.
From what I remember, the concerns about X-rays
didn't appear until the higher acceleration voltages used in color CRTs. I'm not
sure if it's significant even there, unless you're worried about lawyers rather
than reality.
paul
11:46 a.m.
That was my thought too- color CRTs are where this really mattered- which
is why I mentioned black and white.
I am not overly concerned, someone in the IRC channel I'm in asked and I
thought I'd ping. Even then, in a color CRT without any lead shielding, I'd
bet the emissions pale in comparison to any kind of real medical X-ray.
On Fri, Jul 1, 2016 at 11:43 AM, Paul Koning <paulkoning at comcast.net> wrote:
--
Ian Finder
(206) 395-MIPS
ian.finder at gmail.com
On Jul 1, 2016, at 2:41 PM, Ian Finder
<ian.finder at gmail.com> wrote:
I know a few list members who have been doing this, after fixing CRT
cataracts.
Was that glass additionally leaded to cut down on X-rays at all? Is
there a
risk to that?
These are mostly black and white CRTs.
From what I remember, the concerns about X-rays didn't appear until the
higher acceleration voltages used in color CRTs. I'm not sure if it's
significant even there, unless you're worried about lawyers rather than
reality.
paul
12:03 p.m.
On 2016-07-01 2:46 PM, Ian Finder wrote:
That was my thought too- color CRTs are where this
really mattered- which
is why I mentioned black and white.
I am not overly concerned, someone in the IRC channel I'm in asked and I
thought I'd ping. Even then, in a color CRT without any lead shielding, I'd
bet the emissions pale in comparison to any kind of real medical X-ray.
Not a very good comparison because one is pointed at your head for
months or years and the latter is momentary.
--Toby
On Fri, Jul 1, 2016 at 11:43 AM, Paul Koning <paulkoning at comcast.net> wrote:
On Jul 1, 2016, at 2:41 PM, Ian Finder
<ian.finder at gmail.com> wrote:
I know a few list members who have been doing this, after fixing CRT
cataracts.
Was that glass additionally leaded to cut down on X-rays at all? Is
there a
risk to that?
These are mostly black and white CRTs.
From what I remember, the concerns about X-rays didn't appear until the
higher acceleration voltages used in color CRTs. I'm not sure if it's
significant even there, unless you're worried about lawyers rather than
reality.
paul
12:05 p.m.
I am not
overly concerned, someone in the IRC channel I'm in asked and I
thought I'd ping. Even then, in a color CRT without any lead shielding, I'd
bet the emissions pale in comparison to any kind of real medical X-ray.
Not a very good comparison because one is pointed at your head for
months or years and the latter is momentary. 
1:08 p.m.
Not a very good comparison because one is pointed at
your head for
months or years and the latter is momentary.
On Fri, 1 Jul 2016, tony duell wrote:
I am not convinced that the effect is purely cumulative anyway. In other words,
a lower intensity (and lower energy) beam for longer might not do as much
damage as a brief pulse from a high intensity, high energy source.
The "pro-nuclear" community calls it the "LNT" ("Linear No
Threshold")
premise.
How much of the health damage of early color TV was due, not to the
hardware, but to the quality of the content?
(USA networks were/are clearly worse than BBC)
1:40 p.m.
On 2016-07-01 4:08 PM, Fred Cisin wrote:
Granted. But this is all well studied, we can just look up the numbers
and the science. Probably something people using unshielded CRTs are
best motivated to do.
--Toby
Not a very
good comparison because one is pointed at your head for
months or years and the latter is momentary.
On Fri, 1 Jul 2016, tony duell
wrote:
I am not convinced that the effect is purely cumulative anyway. In other
words,
a lower intensity (and lower energy) beam for longer might not do as
much damage as a brief pulse from a high intensity, high energy source.
The "pro-nuclear" community calls it the "LNT" ("Linear No
Threshold")
premise.
How much of the health damage of early color TV was due, not to the
hardware, but to the quality of the content?
(USA networks were/are clearly worse than BBC)
6:27 p.m.
" I do remember
reading that the EHT rectifier diode valves and shunt stabiliser triodes in
early
colour TVs gave off enough Xrays to be dangerous"
This is true. I have here an old HV octal-base tube rectifier that came out
of a color set. The vacuum envelope itself is encased in a second outer
envelope, which seems to be made of something like 3/16" lead. The outer
envelope carries multiple warnings about x-ray emissions, and instructs you
to avoid arcing the anode to the case, or causing any other sort of
mechanical shock or damage as it may reduce the x-ray safety.
Of the countless thousands of tubes I've sorted, this is the only one I've
ever come across.
On Fri, Jul 1, 2016 at 3:40 PM, Toby Thain <toby at telegraphics.com.au> wrote:
On 2016-07-01 4:08 PM, Fred Cisin wrote:
Not a very good comparison because one is pointed
at your head for
Granted. But this is all well studied, we can just look up the numbers and
the science. Probably something people using unshielded CRTs are best
motivated to do.
--Toby
months or years and the latter is momentary.
On Fri, 1 Jul 2016, tony duell wrote:
I am not convinced that the effect is purely cumulative anyway. In other
words,
a lower intensity (and lower energy) beam for longer might not do as
much damage as a brief pulse from a high intensity, high energy source.
The "pro-nuclear" community calls it
the "LNT" ("Linear No Threshold")
premise.
How much of the health damage of early color TV was due, not to the
hardware, but to the quality of the content?
(USA networks were/are clearly worse than BBC)
2 Jul
2 Jul
7:40 a.m.
I suspect the warning about arcing was that it could damage the regulator.
The voltage would increase, increasing the Xray level.
Depending on the metal being hit by electrons, it take a minimum level
before Xray emission starts. As I recall, the regulator on a color TV
was intended to keep it below that threshold.
Dwight
________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of drlegendre .
<drlegendre at gmail.com>
Sent: Friday, July 1, 2016 6:27:27 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Running CRTs without implosion protection glass
" I do remember
reading that the EHT rectifier diode valves and shunt stabiliser triodes in
early
colour TVs gave off enough Xrays to be dangerous"
This is true. I have here an old HV octal-base tube rectifier that came out
of a color set. The vacuum envelope itself is encased in a second outer
envelope, which seems to be made of something like 3/16" lead. The outer
envelope carries multiple warnings about x-ray emissions, and instructs you
to avoid arcing the anode to the case, or causing any other sort of
mechanical shock or damage as it may reduce the x-ray safety.
Of the countless thousands of tubes I've sorted, this is the only one I've
ever come across.
On Fri, Jul 1, 2016 at 3:40 PM, Toby Thain <toby at telegraphics.com.au> wrote:
On 2016-07-01 4:08 PM, Fred Cisin wrote:
Not a very good comparison because one is pointed
at your head for
Granted. But this is all well studied, we can just look up the numbers and
the science. Probably something people using unshielded CRTs are best
motivated to do.
--Toby
months or years and the latter is momentary.
On Fri, 1 Jul 2016, tony duell wrote:
I am not convinced that the effect is purely cumulative anyway. In other
words,
a lower intensity (and lower energy) beam for longer might not do as
much damage as a brief pulse from a high intensity, high energy source.
The "pro-nuclear" community calls it
the "LNT" ("Linear No Threshold")
premise.
How much of the health damage of early color TV was due, not to the
hardware, but to the quality of the content?
(USA networks were/are clearly worse than BBC)
8:42 a.m.
Depending on the metal being hit by electrons, it take
a minimum level
before Xray emission starts. As I recall, the regulator on a color TV
was intended to keep it below that threshold.
The whole color TV xray scare was mostly just that - a scare. Even the
old "roundie" color sets did not pose a hazard under normal operating
conditions, but the scare was intense enough to cause the 3DR3 and
3DS3 tubes to appear for a very short time. They are now somewhat
scarce, so do not pitch any you find. The jacket on the tubes is a
lead impregnated rubber.
The issue is if the regulator stops working, then a set might go
haywire enough to cause x-rays to form - but in real life, this would
generally kill the whole set, or make it unwatchable enough that the
viewer would generally turn the set off.
So basically under freak conditions, some x-rays can be present.
--
Will
1 Jul
1 Jul
1:42 p.m.
New subject: Toss your TV - was Re: Running CRTs without implosion protection glass
On 2016-07-01 4:08 PM, Fred Cisin wrote:
The content has only deteriorated since then.
--Toby
Not a very
good comparison because one is pointed at your head for
months or years and the latter is momentary.
...
How much of the health damage of early color TV was due, not to the
hardware, but to the quality of the content?
(USA networks were/are clearly worse than BBC) 
12:27 p.m.
On 7/1/2016 2:03 PM, Toby Thain wrote:
On 2016-07-01 2:46 PM, Ian Finder wrote:
The body can handle very low-level,
constant radiation. This is
self-evident as radiation exists pretty
much everywhere naturally -- at a very
low level.
It gets problematic either above a
certain constand level, or with sudden
(or instantaneous) higher doses. Dose
over time matters, but there is
apparently some cumulative effect as well.
- J.
That was my thought too- color CRTs
are where this really mattered- which
is why I mentioned black and white.
I am not overly concerned, someone in
the IRC channel I'm in asked and I
thought I'd ping. Even then, in a
color CRT without any lead shielding,
I'd
bet the emissions pale in comparison
to any kind of real medical X-ray.
Not a very good comparison because one
is pointed at your head for months or
years and the latter is momentary.
--Toby
12:30 p.m.
On Jul 1, 2016, at 3:27 PM, js at cimmeri.com wrote:
On 7/1/2016 2:03 PM, Toby Thain wrote:
Self evident except to those weirdos who cling to the "no safe level" myth. A
very nice myth if you're a dishonest lawyer -- it pays the bills.
paul
On 2016-07-01 2:46 PM, Ian Finder wrote:
The body can handle very low-level, constant radiation. This is self-evident as
radiation exists pretty much everywhere naturally -- at a very low level. That was my thought too- color CRTs are where
this really mattered- which
is why I mentioned black and white.
I am not overly concerned, someone in the IRC channel I'm in asked and I
thought I'd ping. Even then, in a color CRT without any lead shielding, I'd
bet the emissions pale in comparison to any kind of real medical X-ray.
Not a very good comparison because one is pointed at your head for months or years and
the latter is momentary.
--Toby
11:44 a.m.
I know a few list members who have been doing this,
after fixing CRT
cataracts.
Was that glass additionally leaded to cut down on X-rays at all? Is there a
risk to that?
It probably was leaded glass, but mono CRTs only run at about 15kV on the
final anode. I don't think you get much of an X ray risk from that.
The older TV CRTs (at least in the UK) had a separate implosion guard that
was either a sheet of laminated glass, or later on a tough plastic sheet or
'bowl'. I don't think those (particularly the latter) would be much of an X
ray
shield, nor do I ever remember seeing warning about X ray hazards when
repairing such sets (which might involve running the CRT out of the cabinet,
and thus without the shield in place.
Colour CRTs might be a different matter. AFAIK all the ones used in the
UK TVs had integral implosion protection so there was never any suggestion
that they could be run without that. And they run at 25kV EHT. I do remember
reading that the EHT rectifier diode valves and shunt stabiliser triodes in early
colour TVs gave off enough Xrays to be dangerous, I never saw similar
warnings about the rectifier valves in monochrome TVs.
-tony
3095
days inactive
3096
days old
13 comments
9 participants
participants (9)
-
ard＠p850ug1.demon.co.uk -
cisin＠xenosoft.com -
dkelvey＠hotmail.com -
drlegendre＠gmail.com -
ian.finder＠gmail.com -
js＠cimmeri.com -
paulkoning＠comcast.net -
toby＠telegraphics.com.au -
wdonzelli＠gmail.com