General Forum

Re: A shocking question

The Stig - ver. 1.7 — Wed, 09 Apr 2008 17:36:24 GMT

When you take your LCD screen apart you will find, that it's housed in a metal box and as long as your on this side of it your OK

Re: A shocking question

Peter — Wed, 09 Apr 2008 16:22:13 GMT

I would talk to Richard about this (a2bur) It sounds like one of his projects!!

Re: A shocking question

camshaft — Wed, 09 Apr 2008 14:05:15 GMT

Yeah, assuming you're not in a rush, which you shouldn't be, just unplug the thing the day before you go to work on it.

Re: A shocking question

Puncher — Wed, 09 Apr 2008 13:57:24 GMT

LCD backlights use Inverters which electronically generate high frequency "mains-type" voltages. Normally, inside appliances, there is a rule that high voltage caps across the mains cord must discharge to less than 34V within one second but this doesn't apply to internal circuits and so caps can retain their charge for extraordinary lengths of time. The best plan is to discharge any suspect caps with a suitable resistance (do not short them with pliers etc). The circuit schematic is always the best indication of what is likely to need discharging - I suppose a rule would be "if you can't read the schematic - don't dabble". On the other hand if the appliance hasn't been powered up for a day there is little chance of anything retianing any hazardous voltages.

Re: A shocking question

Alex — Wed, 09 Apr 2008 13:06:43 GMT

The actual LCD element itself uses a 12v charge I believe, but this doesn't include the other components.

Just to be safe, I'd wear rubber gloves and leave it unplugged from the mains to discharge for some time...

Re: A shocking question

Graham1982 — Wed, 09 Apr 2008 11:31:29 GMT

Hi:

Thanks, how long should I wait for the CAPS to discharge? I have worked on PCs which obviously have CAPS on them and have never been shocked. Is it just a case of common sense - don't mess around with the power supply, don't mess around with it whilst switched on etc?

Thanks

Graham

Re: A shocking question

camshaft — Wed, 09 Apr 2008 11:09:00 GMT

Regardless of the voltage, if you unplug the set first, and wait for the caps to discharge, I really don't see how you'd get shocked by working on it. LCD's use lower voltages, but the power supplies are typically located inside the housing, so there will still be 240v up until you get to the supply.

A shocking question

Graham1982 — Wed, 09 Apr 2008 09:37:40 GMT

Hi all:

I have another project on the go that I will probabl get half way through and then not be bothered to finish it. Well at least whilst it holds my interest in will keep me out of trouble:

What I am intending to do is get an old television of iconic "of its era" design - namely an old Ferguson from the 70s/80s or a Bakerlite model, remove the innards and put a stripped down PC with LCD screen, Freeview etc in it. Like a retro media centre.

I am hoping to get most of the components from Freecycle.

What I would like to know is, do LCD monitors/screens carry the same high voltages as CRTs? I think that I may actually have to take the LCD screen out of its casing to make it look/fit better inside the old TV case. However, I do not really want to get 240v through my hands.

Has anyone on here tried something similar? I have heard of people doing it and was thus wondering what are the things to look out for are etc.

Thanks

Graham