2 parts of computer that can be dangerous to mess with

[osx]

unless you are trained of course...

1. CRT- this is the monitor, and/or parts of it. Don't mess with it unless you've been trainined. Why? Even after the computer is shut off and unplugged, the CRT holds dangerous amounts of electricity! Not good. You could hurt yourself, perhaps even fatally.

2. Power supply- I believe this holds power after being shut off too, at least for some time. So I would not mess with it unless trained.

I learned this stuff while starting to study for the A+ exam... thought I would share it with you "do it yourself" computer people.

 

[Audiomechanic]

I second that. Never been hit by the coil or capacitors on a CRT monitor, but have seen what the power can do. Co worker of mine was trying to remove the CRT tube and cut the wires running to the coil from the main board and the BIG caps with wires cutters before properly discharging the caps. He was wearing gloves and the wire cutters had rubber handles so he didn't get hurt, but the power essentially melted the ends of the solid STEEL wire cutters and sent sparks everywhere!

Powerful stuff in those monitors. 60,000 volts if I remember correctly from electronics school.

 

[Mikesoft]

hehe, I am starting to feel afraid looking at my crt monitor!

I knew psu held a charge but did not realise crt monitors did to!

 

[Overtime_man]

People still use crt monitors?

 

[Battie]

I opened a PSU once to try to replace the fan (we didn't have a spare that fit). I was kind of freaked out the whole time, but they told me to do it...

 

[BOJAX]

lol sheesh, I was just cleaning out my monitor and power supply the other day.

CRT's freak me out. Especially when they are open.

I don't know why but I just get the feeling like a crt monitor would eventually explode while I'm sitting here. And big thick shards of glass getting shot into my face.

I don't think I should be a computer technician.

 

[Ragnaros]

Wow, I had heard that messing with a CRT monitor is dangerous, but had no idea that there are 60,000 volts running through parts of it.
Thankfully I've never had problems with my PSU (Antec TruePower550), so I've never had to work on it.

 

[furry001]

Sound advice, and one that we would be good to follow.

CRT's are still being used because they tend to last a lot longer (and are cheaper) that TFT Flatscreen models.

Never mess with PSU's either. Not good.

 

[Mikesoft]

People still use crt monitors?

Yes

I have issues with the flat screens. It is such a gamble when you buy one because you may get dead pixels and crt monitors still visually much better that flatscreens.

However... having said that I am getting a 19" flatscreen monitor for xmas!

Will I be converted to the TFT side???

 

[Audiomechanic]

Sound advice, and one that we would be good to follow.

CRT's are still being used because they tend to last a lot longer (and are cheaper) that TFT Flatscreen models.

Never mess with PSU's either. Not good.

Exactly. That and a Flat panels still cannot mach the pixel definition or the refresh rate of that of a CRT.

 

[theartist87]

I mess with power supplies every day, much easier to replace a dead fan on a weird power supply, than buy a replacement from sony for $140. Just got to make sure it's been off for a while... Still, I don't suggest that other people do the same... Sometimes what I just do is pure dangerous, nobody should be doing it.

 

[Audiomechanic]

Computer power supplies do hold some power but not nearely enough to kill you. Maybe enough to stun you but that's about it. Monitors on the other hand, do have enough power to kill you very easily. If anyone works inside of a CRT, discharge the coil and caps first. Usually involves taking an electricians screwdriver (one with a handle made of rubber or one with rubber around it), stripping a 3-6 foot long piece of 16-12 guage wire at both ends, wrapping one end around the metal shaft of the screw driver and sticking the other end into the third hole (ground) of an outlet. Then touch the screw driver to the coil and to both leads of all caps on the board. The jolt from the coil might scare you if you've never discharged a monitor before, but better to scare you have have the electricity run into the outlet and then the ground, than have it run into you. Once it's discharged, it's safe to work with.

 

[Quantos]

True you can discharge a cap by shorting it, but that's not the best or safest way to go.

To properly discharge the cap, you want to use a High watage Resister 1-2K should work, and leave it on, check the V with a meater to verrify that it is at 0V before working, and No sparks, or risk of damaging anything by the discharge.

 

[rosenherman]

pibcak

 

[BOJAX]

True you can discharge a cap by shorting it, but that's not the best or safest way to go.

To properly discharge the cap, you want to use a High watage Resister 1-2K should work, and leave it on, check the V with a meater to verrify that it is at 0V before working, and No sparks, or risk of damaging anything by the discharge.

I have to say I feel much safer with this method.

 

[Audiomechanic]

True you can discharge a cap by shorting it, but that's not the best or safest way to go.

To properly discharge the cap, you want to use a High watage Resister 1-2K should work, and leave it on, check the V with a meater to verrify that it is at 0V before working, and No sparks, or risk of damaging anything by the discharge.

We do it the lazy way, I guess.

 

[Psalms34]

unless you are trained of course...

1. CRT- this is the monitor, and/or parts of it. Don't mess with it unless you've been trainined. Why? Even after the computer is shut off and unplugged, the CRT holds dangerous amounts of electricity! Not good. You could hurt yourself, perhaps even fatally.

2. Power supply- I believe this holds power after being shut off too, at least for some time. So I would not mess with it unless trained.

I learned this stuff while starting to study for the A+ exam... thought I would share it with you "do it yourself" computer people.

Yeah, my college instructor went over those two in my A+ support class. Those two were the only two components that he would not let anyone pull apart in lab. I learnt how to handle that in High School though, I had four semesters of Electronics and my teacher would go berserk and smash monitors and TV’s in class and make us clean it up lol. That was after he taught us how to handle that stuff of course.

 

[Overtime_man]

Yes

I have issues with the flat screens. It is such a gamble when you buy one because you may get dead pixels and crt monitors still visually much better that flatscreens.

However... having said that I am getting a 19" flatscreen monitor for xmas!

Will I be converted to the TFT side???

I think that most manufacturers will replace a flatscreen if the number of dead pixels exceeds a certain threshold. As far as image quality goes, you get what you pay for. Some of the better cinema displays from Apple are comparable to top of the line crt monitors. And of course one of the biggest advantages to flatscreens is that they don't take up half of your desk space like crts do.

 

[Quantos]

I've got 2 19" on my desk, no dead pixles that I can see.

Nother good thing about LCD displays (Not Flatscreens, as a CRT can be a Flatscreen also ) is they don't use as much power as a CRT.

 

[mnphysicist]

Its been years since I've played with CRT's but I doubt the flyback voltage is 60KV. If it were, it would seem one would be getting slammed with xrays. In the old days, they had spark gaps to limit CRT voltage to no more than 28KV to limit xray exposure on tv sets. Unless they fixes that problem in computer monitors with shielding, or radically different phosphor design, the same physics would seem to apply.

A PSU's caps will bleed off over a short period of time. I've seen CRT's hold 20KV for a month or more after being turned off and unplugged. Only nailed myself once with a CRT, but tens of times designing PSU's. Both hurt, but the CRT has the a greater potential to be deadly. We used to follow the one hand in the back pocket rule as a safety measure, not sure how valid it was, but no one died from a CRT that I know of... but its still a statistics issue, and if you or someone you know gets taken out, stats are of no comfort.

Ron