The proper way to discharge electricity from a flat screen before working on it.

[Heihachi_73]

Re: The proper way to discharge electricity from a flat screen before working on it.

An old flat blade screwdriver works for me. Plenty of those to find in the junk if you are afraid of damaging your daily-used tools.

[budm]

Re: The proper way to discharge electricity from a flat screen before working on it.

FYI: I use 25W lamp (cold resistance is more than 10 Ohms), not good to discharging the cap at higher than the ripple current rating.


Observe charge-discharge limitations.
Frequent charge-discharge load via low resistance may cause capacitance drop or destroy the
capacitor. Under well defined conditions (see section “Tests and Requirements”) frequent
charge-discharge operation is allowed. The resulting current through the capacitor must not exceed the
ripple current limit. Standard aluminum capacitors are not suitable for flash applications

[eccerr0r]

Re: The proper way to discharge electricity from a flat screen before working on it.

they are UL because of the fact that most are put inside of a non conductive cabinet like bakelite or wood plus the fact that some that don't predate UL have the secondary HV 375v DC + at the chassis.
but yes some do predate UL like my coronado, but to answer your question, the live chassis issue (if you call it that) predates UL, but UL didn't take notice for a long time.

Ah, it looks like not all of them are live chassis. Just the earlier ones had live chassis (but if working on these, one needs be careful in case you get an old one!). UL currently requires double insulation to be certified, and if the internal metal chassis behind the Bakelite is not hooked up to one side of the power plug, then that qualifies as double insulated. It looks like only the first ones made where they cheaped out on the return line they tied the chassis to one side of the power plug - so even if it was encapsulated in wood or other insulating material, it would not qualify. The later radios apparently have an internal return ground wire that wasn't the chassis, adding one layer of insulation, and thus satisfies the current UL requirement.

I'm still looking for one for the heck of it, I wonder if I'll first get one with a "live" chassis or not... and how much effort it'd take to mod it such that it would meet UL-standards...

[pixellegolas]

Re: The proper way to discharge electricity from a flat screen before working on it.

Sorry for resurecting this old thread but I am about to open up my plasma TV to solder some and seems hard to find good tutorials on safety first. Aren't there any good videos now 2019 that shows how to safely remove charge in a tv? Like a newbie guide? Feels like that is way more important than alot of other things

[pixellegolas]

Re: The proper way to discharge electricity from a flat screen before working on it.

Oh, just to be clear, I found a thread about "red haze" on a LG plasma and seems it's the Y-sus or X-sus that needs some soldering on the backside, but I am afraid to tuch them right now as they are

[pixellegolas]

Re: The proper way to discharge electricity from a flat screen before working on it.

Ok, just found that you can use the resistor as mentioned before and seems very easy, just like this guide with pics show

http://www.electronicrepairguide.com...discharge.html

But, is it safe to take away the board in the first place? I saw on some video that the heatsink still can give you a shock so how do people in the first place remove a board to be able to get to the backside and put on the resistor?

[pixellegolas]

Re: The proper way to discharge electricity from a flat screen before working on it.

Sorry for all these posts but this is what I will do:

- Turn off plasma tv and let it set for a while
- Get a multimeter
- Get a resistor with high enough value (this is where I am stuck now, what is high enough)?
- Remove board
- Put the resistor on the capacitor backside
- Re-solder the cold solder
- Reap the reward

Is the resistor value the only key here to think about?

EDIT: Saw a video now on youtube, a too small resistor will lead to spark and to high leads to very slow discharge, so I think the best bet is to actually use a resistor calculator and get as close as possible

[pixellegolas]

Re: The proper way to discharge electricity from a flat screen before working on it.

Talking to myself here but I did according to all tutorials and voila, I have fixed my plasma tv with "red haze" problem. Thanks all for the information provided