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n/a
deleted
8 Posts |
 Posted - 04/30/2007 : 13:38:47
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Old tv’s may have up to 4 lb. of copper wire. May be worth picking up sets by side of road strip them and then set them out again
The parts worth your effort are the degaussing coil around the picture tube and the yoke on the neck of the tube. Most degaussing coils come out easy by cutting the plastic holders; some require the tube to be removed. 27 inch sets have 2-4 lb. of copper. Newer sets use aluminum. Use a razor knife to cut the tape then pull the copper out. Most sets have the yoke secured with a clamp remove the yoke from the tube and break the yoke up with a hammer. Most yokes are less than 1 lb. of copper. Also look for a coil of wire taped to tube around the yoke
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Cerulean
Penny Hoarding Member
USA
993 Posts |
Posted - 04/30/2007 : 14:25:29
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I'll keep this in mind in 2009 when the US mandate for HD broadcasts goes into effect. I expect a lot of older TV sets to hit the curb once they aren't able to pull antenna reception anymore.
RUNNING TOTAL
--------------------------
2854 zincs (1982-2007) 75.5%
898 coppers (1959-1982) 23.7%
23 wheats (1920-1958)
6 Canadian (1968-1995)
1 dime (2004)
Wanna take money away from the Fed? Spend dollar coins! |
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psi
Penny Collector Member
Canada
399 Posts |
Posted - 04/30/2007 : 17:14:47
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Thanks for the tips redcc, welcome to the forum. When I see TVs and VCRs at the curb I often bring them home and see if they work. A surprising number work quite well. Are the degaussing coils only in newer TVs with a degauss feature, or what? Do PMs turn up in TVs at all? In a Sony VCR I dissected once there was a bit of what I think is probably gold on some circuit board contacts.
Regarding the HD switchover, I heard there was a massive amount of money set aside to subsidize boxes for viewing HD broadcasts on old TVs, so some people will stick with them for a while. I'm sure there'll be tons of TVs out every garbage day for quite a while once the switchover takes place though. In a big city you could probably go cruising for copper every day, just going to whatever area has its garbage day that day. Don't forget about power cords and transformers for copper either. |
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Metalophile
Penny Collector Member
USA
320 Posts |
Posted - 05/01/2007 : 01:14:38
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Be very careful! CRT's can hold a fatal capacitive charge, even after being powered down for a long time. Anyone know how to safely bleed that charge off?
Metalophile |
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psi
Penny Collector Member
Canada
399 Posts |
Posted - 05/01/2007 : 09:02:27
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Here's one link on that: You must be logged in to see this link.
* For the CRT, use a high wattage (not for power but to hold off the high
voltage which could jump across a tiny 1/4 watt job) resistor of a 1 to 10
M ohms discharged to the chassis ground connected to the outside of the
CRT - NOT SIGNAL GROUND ON THE MAIN BOARD as you may damage sensitive
circuitry. The time constant is very short - a ms or so. However, repeat
a few times to be sure. (Using a shorting clip lead may not be a bad idea
as well while working on the equipment - there have been too many stories
of painful experiences from charge developing for whatever reasons ready
to bite when the HV lead is reconnected.)
Capacitor discharge tool
A suitable discharge tool for each of these applications can be made as
quite easily. The capacitor discharge indicator circuit described below
can be built into this tool to provide a visual display of polarity and
charge (not really needed for CRTs as the discharge time constant is
virtually instantaneous even with a muli-M ohm resistor.
* Solder one end of the appropriate size resistor (for your application)
along with the indicator circuit (if desired) to a well insulated clip
lead about 2-3 feet long. For safety reasons, these connections must be
properly soldered - not just wrapped.
* Solder the other end of the resistor (and discharge circuit) to a well
insulated contact point such as a 2 inch length of bare #14 copper wire
mounted on the end of a 2 foot piece of PVC or Plexiglas rod which will
act as an extension handle.
* Secure everything to the insulating rod with some plastic electrical tape.
This discharge tool will keep you safely clear of the danger area.
Again, always double check with a reliable voltmeter or by shorting with
an insulated screwdriver! |
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Metalophile
Penny Collector Member
USA
320 Posts |
Posted - 05/02/2007 : 08:01:31
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Thanks for the info, PSI!
Just to make sure, I've never opened any TV's up to get a good look inside. The outside surface of the CRT is silvered, and this silver surface is where the charge builds up, right?
Metalophile |
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horgad
1000+ Penny Miser Member
USA
1641 Posts |
Posted - 05/02/2007 : 09:24:08
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I'm no TV expert but I believe in TVs and certain other electronnics it is the capacitors that get you. Some devices need a kick start of juice to get them going so they built up a super charge in a capacitor. I have seen and replaced these in my heat pump and well pump control. They look like a small can with wire connectors at one end. I'm not sure what they look in a TV, but I imagine they are smaller maybe even on a circuit board where you can't really see them easily.
You must be logged in to see this link. |
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Metalophile
Penny Collector Member
USA
320 Posts |
Posted - 05/02/2007 : 14:24:40
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I found a CRT repair FAQ which covers the discharge of the CRT and other capacitors in detail:
You must be logged in to see this link.
In summary, the rear glass of a CRT has a conductive coating on both sides, forming a high voltage capacitor. Most newer TV's are equipped with bleeder resistors to dissipate this charge, but if this bleeder is broken or the TV is an older model, it can give you a nice shock. Even if you bleed off this charge, some charge can remain actually stored in the glass, and a voltage can reappear! Outside part of the tube is ground, inside is connected to an anode cable, and that's (one of the places) where high voltage resides other than the conventional capacitors.
Also be aware that the CRT is a big vacuum tube, so avoid breaking it, or you will have lots of flying glass!
Peace and Safety!
Metalophile |
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n/a
deleted
8 Posts |
Posted - 05/04/2007 : 16:49:26
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got busy fixing tv's and didn't get back till now
you don't need to remove or touch the high voltage wire to remove most degausing coils. just cut the coil and take it off
most color tv's have degausing coils except very old sets from the 60's and some dc only tv's.
caps in tv's don't hold a charge very long(hours?) if you find a set sitting out for the trash and you only want the copper don't plug it in. to be safe don't touch the bottom of the circuit board
I've worked on them for 30 years, now i'm use to the shock from the tube and i don't think about it much.pulling away from the shock will hurt more then the shock, when you cut your arm on something sharp in the set. to discharge the high voltage use a long screw driver with a plastic handle, wrap a wire around the shaft of the screwdriver and then connect other end of the wire to the braded wire (ground wire) straped under the tube from mounting tabs at bottom sides of the tube. holding the plastic handle of the screwdriver slide the blade under the rubber boot at the top of the tube till it touches the metal connector holding the wire to the tube. it may have a high voltage arc (snap noise). most sets hold a charge about a week or two. If you need to break the tube or don't want it to implode if someone else gets around it. remove the socket from the tube put pliers on the pins at the end of the tube and squeeze the pins (some have a plastic cap to hold the pins) and twist to break the small tube they used to pull the vacuume on the tube, it will hiss when the glass breaks. it's then as safe as a piece of broken glass can be. |
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copper from tv's
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