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JPhys7
Joined: 04 Jan 2009
Posts: 2
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| Posted: Sun Jan 04, 2009 5:18 am Post subject: CRT Safety |
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I am new to CRTs and have been messing around a little with a CRT projector and I want to make sure I am clear on safety. This is what I have gathered from reading around. Is there anything else I need to be careful of?
1. Tube Implosion
2. High-Voltages\Electrical Shock - unplug and discharge caps. before servicing
3. Screen Phosphors are toxic - only matters when tube has been broken
4. Glycol is toxic (I suppose only if you consume it or get large quantities on your skin, but otherwise no worries?)
Thanks.
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CRT_Ben
Joined: 28 Aug 2006
Posts: 1684
Location: Northern Virginia
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| Posted: Sun Jan 04, 2009 5:36 am Post subject: Re: CRT Safety |
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| JPhys7 wrote: | I am new to CRTs and have been messing around a little with a CRT projector and I want to make sure I am clear on safety. This is what I have gathered from reading around. Is there anything else I need to be careful of?
1. Tube Implosion
2. High-Voltages\Electrical Shock - unplug and discharge caps. before servicing
3. Screen Phosphors are toxic - only matters when tube has been broken
4. Glycol is toxic (I suppose only if you consume it or get large quantities on your skin, but otherwise no worries?)
Thanks. |
You pretty much have the right idea - the only real danger you have while working on a running CRT is electric shock. The tubes, while fragile, would have to be abused to shatter. You may know this already but look on the main part of Curt's site in the tips and tricks/ projector layout section for your projector and get to know it a little bit, what parts carry high voltage and what don't. Always work with one hand out of the projector, in your pocket or behind your back to prevent any shock from going through your heart if you do get zapped. And glycol - yes, toxic to drink (keep it AWAY from pets and little ones because glycol is sweet tasting!), but not really a problem on the skin unless you really go overboard.
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AnalogRocks
Forum Moderator
Joined: 08 Mar 2006
Posts: 26706
Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Sun Jan 04, 2009 6:28 am Post subject: |
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Just to add. Glycol is corrosive. Don't spill it on anything you want to keep and if it get's on a circuit board clean it immediately.
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HD done right!
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zGman
Joined: 22 May 2006
Posts: 599
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| Posted: Sun Jan 04, 2009 7:14 am Post subject: |
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Remove all jewelry before working with high voltage electronics.
(or woodworking, machining, welding, etc)
Many crt setup operations involve adjusting coils and magnets while
the machine is running, your wedding ring could be the end of you.
G
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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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| Posted: Sun Jan 04, 2009 7:21 am Post subject: |
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Dry high voltage rubber gloves might also be helpful. Use just one hand and avoid ground connection with the chassis. Never had a problem so far 
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CasetheCorvetteman
Joined: 09 Nov 2008
Posts: 6326
Location: Australia
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| Posted: Sun Jan 04, 2009 8:17 am Post subject: |
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| zGman wrote: | .... your wedding ring could be the end of you.
G |
Ive heard that too 
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MrCRTing
Joined: 03 Feb 2008
Posts: 35
Location: Brighton UK
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| Posted: Sun Jan 04, 2009 3:08 pm Post subject: CRT Safty |
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Hi
Glycol in the eye is not a good idea, it stings to high heven, don't ask how this happned )o:
If your removing the CRTS is will be worth shorting the EHT lead to the side of the tube (aguadag) or metal chassis to remove any stored energy, CRT can hold charge for hours or even days.
In my early years of TV repair I had a set / tube that held charge for 5 days and it went crack big time when shorted to aguadag.
Just be carefull, remove anything metal on hands and wrists.
MrCRTing
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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zGman
Joined: 22 May 2006
Posts: 599
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| Posted: Sun Jan 04, 2009 4:12 pm Post subject: |
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That one sounds scary to me! I think I will pass on the ground strap.....!
I have gotten hit a little by Barco neckboards and Marquee deflection coils,
and it is not fun - the hard part is having enough self-control to avoid a
spastic movement which would damage something or end up somewhere
worse. The idea of heatshrinking over the exposed pins on the deflection
coils is a very good one. For a good setup the coils have to be leveled and
the convergence coils must be set properly, which puts you in there quite
a while, in the dark, with both hands. Barco and Sony have plastic covers.
G
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Ohmess
Joined: 11 Sep 2008
Posts: 242
Location: Vienna, VA
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| Posted: Sun Jan 04, 2009 4:38 pm Post subject: |
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On a related question, my projector seems to generate a fair amount of static electricity. (This is new since I changed the tubes and focus coils.) I went over all the ground straps to ensure they are connected.
Is there any concern here?
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MikeEby
Joined: 24 Jun 2007
Posts: 5237
Location: Osceola, Indiana
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| Posted: Sun Jan 04, 2009 4:40 pm Post subject: |
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This might be a good sticky thread, old timers like me take these things for granted, where a newbee coming from the digital world may not understand the risks.
Mike
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Sun Jan 04, 2009 6:53 pm Post subject: |
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| Ohmess wrote: | On a related question, my projector seems to generate a fair amount of static electricity. (This is new since I changed the tubes and focus coils.) I went over all the ground straps to ensure they are connected.
Is there any concern here? |
You did the frankenyokes right? make sure the ground wire on pin one from the frankenyoke is grounded tot he chassis somewhere, also if you used the metal clamps from the Sony coils you should solder i wire to the clamp and ground that as well. I used the non metallic clamps from the Marquee's convergence coil and others that Electrohome used.
Athanasios
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stefuel
Joined: 07 Mar 2006
Posts: 3353
Location: Green Harbor MA USA
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| Posted: Sun Jan 04, 2009 7:26 pm Post subject: |
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| Nashou66 wrote: | I heard you should wear a ground strap around the wrist of the hand your using in the pj, this way the current will go into your hand and back through the ground strap around your wrist to the chassis. Kinda skeptical about that one does any one do this or hear of this?
Athanasios |
And like I told Pete, "you should always discharge large capacitors with your tongue before you chance putting your hand in there" I actually think he believed me and did it. That's where his fondness foe AmPro's comes from
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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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| Posted: Sun Jan 04, 2009 7:32 pm Post subject: |
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MrCRTing
Joined: 03 Feb 2008
Posts: 35
Location: Brighton UK
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| Posted: Sun Jan 04, 2009 8:41 pm Post subject: CRT Safty |
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| Nashou66 wrote: | I heard you should wear a ground strap around the wrist of the hand your using in the pj, this way the current will go into your hand and back through the ground strap around your wrist to the chassis. Kinda skeptical about that one does any one do this or hear of this?
Athanasios |
Most cheep ESD straps don't often have a 1M ohm resistor in them only the proper earth bonding point / plug in bonding device does.
Put it this way I would not wear an ESD wrist strap even with a 1M ohm resistor that’s earthed to the chassis of say the PJ while working on the High voltage / changing the tubes as if you accidentally come into contact with a live / charged terminal / tube HV lead you are already earthed and if it's the wrong hand you have a path across your chest / heart. and lets face it you will be using both hands when removing the CRT's for sheer ease and the fact they are heavy and fragile.
50ma across the chest is all it takes to kill 
At least at home with shoes on and carpet under foot and wooden floor board under that the chances of sustaining a major electric shock are reduced ,just watch your hands, use one hand when making live adjustments as said by another member.
Only time I would wear a wrist strap is when I'm handling the bare boards when they are not in the PJ if I was that bothered.
When I switch off my Sony 1271 allot of static forms, you can hear it sort of cracking, providing that the CRT earthing strap / aquadag strap is in it's correct position this should be fine, mines never had an issue.
Another tip to discharge capacitors is use a 40 watt light bulb across the cap terminals, don't just short out with a screwdriver, this can damage the capacitor. Always check with a volt meter once done.
Tube Phosphor coating is toxic but you would have to smash the tube and scrape it off the face and then breath allot of it in / eat it to do any long term major damage.
Tube implosion, every CRT employs implosion protection but they should be handled with care as they are very thin around the neck, on an average 8 inch CRT there is about 300 kilos of pressure exerted on the tube face alone basically waiting to get back in the empty space, on a 32 inch TV set its about 1.4 tonnes
The most dangerous bit about the tube is the flying glass as it is razor sharp when broken, the pop is pretty impressive thou 
MrCRTing
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rabies_70
Joined: 15 Feb 2007
Posts: 1189
Location: Carlsbad, CA
TV/Projector: Sony G70Q
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| Posted: Sun Jan 04, 2009 9:56 pm Post subject: |
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One thing I have noticed unmentioned about CRT safety, Is making sure the wife is well serviced so she doesn't mind/notice all the $$$$$ flying out the door while "taking care of crt maintainance"
It can be very unsafe to work with CRTs without taking that first precaution. 
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I am an iconoclast
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JPhys7
Joined: 04 Jan 2009
Posts: 2
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| Posted: Sun Jan 04, 2009 11:04 pm Post subject: |
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Thanks for all the info guys. Much appreciated.
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CasetheCorvetteman
Joined: 09 Nov 2008
Posts: 6326
Location: Australia
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| Posted: Mon Jan 05, 2009 7:17 am Post subject: |
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| rabies_70 wrote: | One thing I have noticed unmentioned about CRT safety, Is making sure the wife is well serviced so she doesn't mind/notice all the $$$$$ flying out the door while "taking care of crt maintainance"
It can be very unsafe to work with CRTs without taking that first precaution. |
I can see how this could be a concern for some, however in my case, my mrs apreciates that a Corvette costs more than a Yugo, and a CRT projector costs more than a digital...
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