We 'fools' learnt plenty Don. Which is why most people in the UK don't consider themselves part of Europe, and never will. If you know anything at all about the UK, you will know that we are a free democracy. Free, that is, to be controlled by a government that has now been in too long, and thinks that it is a dictatorship. You may have seen on your news - because from what I've seen on your TV when I've been there, just occasionally, the TV companies do look up on a map wherabouts the UK is, and carry the odd interest piece - that our wonderful leader Brown (are you aware it's not Blair any more ?) has just signed up to a new European Treaty that we had already rejected, along with a couple of other countries. They said it was different, but all they had actually done, was rename it. Despite promising the country a referendum on the original treaty, Brown then reneged on that, contending that it was not the same treaty that they had promised to ask us whether we wanted ...
You just cannot fight that sort of thing, so whilst we learnt, and understand all about it, we have little option now but to be swept along in Euro-hysteria, and comply with all the nonsense self justifying crap that comes across to us from Brussels :-\\
On Apr 3, 7:13=A0pm, exray wrote: > snipped-for-privacy@yahoo.com wrote: >
Heavens no. I don't fight. I just try to state facts to the best of my knowledge with as little embellishment as I can. I don't know about your soldering tools but we now use only Metcal soldering stations at work besides my personal one at home. Point is a Metcal has a very well defined temperature not likely to vaporize solder - though what tool would?
Tried a very small amount of lead free solder, didn't like how it behaved and then set it aside to keep using leaded solder until I can't get it anymore. The antique stuff I work on has leaded solder so it seems proper to repair it with the same type solder
Oddly, using lead free solder on copper pipe was kind of fun in that the solder had a very well defined melt point that seemed to almost instantly flow. IIRC it was 95% tin, 5% antimony.
Is this Ban Really Necessary? A Critical Investigation of the CRT Ban
The actual EPA procedure is not really specific to CRT's.
Here's a summary of the CRT testing procedure and some results:
(See Methodology starting on page 7).
"Once divided, each section was reduced in size as required by EPA SW846 method 1311, the Toxicity Characteristic Leaching Procedure. The TCLP is the test prescribed by the U.S. EPA to determine whether a solid waste is hazardous by the toxicity characteristic. Each division of a tube was tested separately (i.e. the neck, funnel, and faceplate were analyzed individually). A sample of glass, from 200 to 500 grams, was placed in a stainless steel bowl. The glass was covered by a cloth for protection from airborne glass, and manually crushed with a standard hammer. Intermittently, the glass was separated through a
9.5-mm sieve and the remaining large fraction returned to the bowl for further crushing. The remainder of the glass (that not crushed) was saved. For the face and funnel fractions, the remaining material mass was often large (relative to the amount crushed the test). The rest of method 1311 was completed and the leachate was digested and analyzed for lead using SW846 methods 3010A and 7420."
In other words, pulverize the glass and then test for lead leaching into various pH caustics.
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 jeffl@comix.santa-cruz.ca.us
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS
Most of the x-rays emitted by CRT's come out the BACK of the tube, not the front. The shadow mask blocks most of them. That's also why there's much more lead in the neck of the CRT, than in the face.
This has a fairly good table of lead content in CRT's.
From page 3: "The average CRT for the time period 1995 to 2000, including televisions and monitors, is an 18.63-inch CRT with a lead content that varies from 2.14 lbs to 2.63 lbs." Note that this was in 2001. It's much less now.
None of the current LCD panel manufacturers use lead in their LCD panels. Yet, the People's Republic of California insists on treating LCD panels (pre-pay recycling fee, hazardous waste, special handling, etc) the same way as CRT's. That's probably because they can't tell the difference between a CRT and and an LCD. Sigh.
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 jeffl@comix.santa-cruz.ca.us
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS
X-rays are generated at the point where maximum electron deceleration occurs - ie as the moment they
Hit the colour phosphors.
Are intercepted and absorbed by the shadow mask while on the way there.
In case 1, x-rays travelling towards the viewer are absorbed only by the face glass.
In case 2, x-rays are generated on the reverse side of the shadow mask and then travel both forward and backwards. Those travelling forwards are absorbed by the face glass.
The face glass is many times thicker than the rest of a CRT's glass - so it contains most of the of lead.
The shadow mask itself is made from very thin alloys sheet ( " invar " or nickel-iron) so will not absorb x-rays to any great extent.
Try tin/silver, *no* copper. Nice shiny (sexy looking?) surfaces, easy to solder, have seen no problems in 2 years where circuits get a lot of temperature cycling.
My usual supplier was doing small samples of just about every type that he carried. I'll have a look and see if he still is. What's the melting temperature of that mix, and what's the price like ?
d Yep. See the scribbling of the Coolidge Tube at:
Note the x-rays are produced when they hit the metal anode targe (A) and are *REFLECTED* to wherever they need to be going. The same thing happens in a CRT. The accelerated electrons from the filament hit the shadow mask and produce x-rays which are reflected back towards the filament.
Also see comments on x-rays (ionizing radiation) at:
The metal CRT shadow mask is fairly impervious to x-rays. What electrons go through the holes in the shadow mask to light up the phosphor dots, do not produce x-rays.
Most travel backwards (reflected) which is why the funnel of the CRT has much more lead in it than the screen.
See appendix B at:
For a 19" CRT, the amount of lead is: neck 0.027 lbs funnel 2.1 lbs panel 0.5 lbs frit 0.079 lbs
The shadow mask is made from Invar for mechanical stability. The alignment of the electron beam to the phosphor dots (or lines) is critical to maintain proper convergence. The tube gets warm and having the aperature screen drift would be a bad idea.
When I was young (and stupid), I took some sealed Polaroid ASA 3000 speed "film" sheets, attached some coins to the surface, and plastered them all over a late 1960's vintage color TV, where I was working. After running the TV all day, I developed the pictures, and found a noticeable lightening around the coins. (Polaroid "film" is positive exposure, not negative). The shadow wasn't very distinct. The "film" on the front screen was barely exposed, while the "film" near the Hi-V cable was more noticeable. The "film" had to be attached to the CRT to get any kind of exposure. Those on the cabinet showed no shadows. About the only change that this prompted in my lifestyle was to not leave my loaded film camera on top of the TV set.
--
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
My memory (which might very well be wrong) was that one of the principal sources of X-rays was the HV rectifier. GE got into trouble over excessive X-radiation from their HV rectifier -- though the tube was situated such that the kids would have had to stick their feet under the set (!!!) to receive any significant dosage.
All this being obviously true, it is inconceivable that the ROHS thing has been done out of sheer stupidity - noone is that stupid, even though those in high offices routinely want to look that in order to be left alone. I can think of no plausible explanation for this ROHS madness other than a well planned and executed sabotage action agaist the countries which have (and rely on) an electronics industry. At a scale that large, even the most expensive to bribe officials cost peanuts.
Close. Most HV rectifiers were inside steel boxes, with the flyback transformer. The HV shunt regulator was exposed on some chassis, and were the worst source. GE made replacements with a thick, lead impregnated synthetic rubber coating to modify TVs built with those chassis series. Then changes were made to the entire HV system to eliminate the HV shunt regulator on later designs.
--
aioe.org is home to cowards and terrorists
Add this line to your news proxy nfilter.dat file
* drop Path:*aioe.org!not-for-mail to drop all aioe.org traffic.
http://improve-usenet.org/index.html
The principal source of X-ray emissions on a CRT is from the electrons hitting the slot mask immediately behind the phosphor screen face, as well as electron impacts on the phosphors themselves..
X-rays are exhibited whenever an electron strikes a metal surface.
With things like a welding arc, it is barely measurable and considered negligible. A TV screen, however, is thousands of "arcs" at one time. It is still fairly negligible, however.
No, HV power supplies, even those intended for use as an anode supply, do not emit X-rays.
By this I meant that if it's deeper than groundwater, there's a nearly zero chance of it getting into the water, or being a problem in any other way.
Also, I had run into some information about lead toxicity several years ago that said that naturally-occurring lead compounds are not as much a problem as artificial (industrial) ones, because living beings are evolved to handle the "organic" (I think it was orthophosphate, but am not sure) form of lead, and can more easily flush it out of the body, preventing bioaccumulation. I tried just now to find that info again, but couldn't. :(
Lead is an element, it is a toxic element, and it can react chemcially to make toxic compounds. It can corrode when exposed to water, and the corrosion by-products are soluble enough that lead found in drinking water comes mostly from the lead in pipes and solder used to hold the pipes together.
References:
formatting link
formatting link
formatting link
formatting link
I went to the EPA site and did a search on "lead" because it became clear to me from previous discussion here that I really didn't know enough about lead toxicity to write at my usual level of knowledge. As I've said, I know more about other, more toxic, heavy metals, and lead has not been of big concern to me.
What I read at the EPA's site confirmed that there isn't much cause for concern with regards to the lead in solder. They say that although there is cause for concern, lead doesn't have as great a bioaccumulation factor as other heavy metals. And they didn't say anything at all about electronic solder or people who work with it, so it looks like those who said they got blood tests that showed no problem are justified to feel they are ok. (If it were me, and maybe it is, I'd still get the test done that uses a hair sample, just to make sure.)
Most of the fuss in the past was about lead-based paint and lead from car exhaust. Both of those have been phased out. (Although recently there have been problems with lead paint being used on toys made in China.)
The EPA hardly mentioned solder at all. As far as I could find, only with regards to water pipe and tin cans (where it is also no longer used).
Looks like I was right about the lead smelting operations, though. And wouldn't you know it, most of that is done in the general region of the planet in which I live (SW USA). By far, most of the lead in use is for car batteries, so I don't see any need to give up leaded solder just for that.
In the Wikipedia article for "solder", it is said that smoke from solder flux can contain a little lead oxide, and that the flux smoke itself can be toxic. So I'll be a little more careful to have good ventilation while soldering. Pretty simple!
Although the EPA noted that metallic lead does corrode, resulting in toxic soluble compounds, they didn't say anywhere (at least that I could find) that lead in landfills is considered a significant problem, and there was no mention of danger from tossing used electronics in the trash.
Jay Ts
--
To contact me, use this web page:
http://www.jayts.com/contact.php
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.