How dangerous is it to replace capacitors?

[Sharcs]

So my monitor died out in a spectacular puff of smoke a couple of days ago and I'm not ready to let it go just yet. I've been looking at some tutorials and the general idea I'm getting is to replace the bulging capacitor/s. In my hunt for information, I've also come across a few posts that say it might be dangerous to poke around in there because some of those pesky capacitors might still hold a charge.

My question is, how dangerous is it to go poking around all those capacitors and how do I safely discharge them if indeed they are an issue?

Monitor is a 2008 Viewsonic Q241WB.

Thanks.

 

[TJ Hooker]

Pretty sure none of the caps in an LCD monitor (or really any other computer part) would have a high enough voltage/be able to store enough energy to hurt you by themselves. And if the monitor's been sitting powered off for a few days, I'm pretty sure any charge on the capacitors will have long since leaked away.

The only risky thing I could think of is that I think some caps have the potential to explode when they fail, and if they're bulging out that means they're close to failure.

 

[Sharcs]

Thanks for the reply.

Mind if I ask a couple more questions coz my monitor is fairly old, bulky, and outputs a lot of heat when in operation - so I just want to be sure.

1) How can I tell if a capacitor packs a punch?

2) Would it be wise to use a screwdriver to try and discharge them just to be sure?

 

[utroz]

You can tell by the amount of Farads it holds.. Discharging them with a screw driver doesn't sound like the best idea to me. Maybe discharge them to a earth ground. I know on some hardware you can discharge them by trying to turn the power on with the power cord unplugged.

 

[ffg7]

as it appears to be a 2 circuit board monitor of a video controller & a power board then be carefully with the power board. I've fixed a number of lcd monitors that had 1 main board & 2 boards. 1 main board monitors use power adapters & 2 board monitors use a regular power cord like what plugs into your desktop computer. I haven't zapped myself yet but then I have been working on circuit boards for about 30yrs. my previous 19" Samsung Frankenstein monitor I put together from 2 different 19"samsungs. the current 24" Samsung monitor I'm using I got from a customer because of a bad main board. replaced 2 caps & monitor has worked perfectly since.

 

[Sharcs]

Ok, last question. I've got the thing opened and there's a mean looking capacitor just staring at me.

Is it dangerous? Can it safely touch other parts of the circuit board? How do I work around it?

Also, the components are glued together with some kind of white glue, how do I get rid of it?

 

[ffg7]

that is the power board. that small upright capacitor to the right of the big 1, does it have some brown stuff on it's top? you can touch the board just not the 2 pin of that big capacitor. also check that the fuse on the power board is still good.

 

[Sharcs]

Thanks guys. Sorry for the delay but it's been a tough month for me, I ended up spending a week in hospital shortly after I made this post then had to go in again last week for surgery. On the bright side I managed to fix my monitor, just replaced all the bulging caps - I'll never throw a monitor out again.

 

[ffg7]

unless the screen is broken then you will.

TJ Hooker, I've seen caps that have been domed for a long time & still working so what you just said is wrong.

 

[TJ Hooker]

TJ Hooker, I've seen caps that have been domed for a long time & still working so what you just said is wrong.

Ok, what I should have said is that bulging can be an indication that the capacitor is failing, but not always. Although, when it comes to caps rupturing, I admit I have no idea how violent it is, and if it would actually be dangerous.

 

[ffg7]

correct. when they actually blow, they go off like a fire cracker. reverse polarize a cap & stand away from it for when it blows.