How to check for a TV "hot chassis

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edgar007

Joined Jan 26, 2012
2
New Member: edgar 007
As a student studying HOME ENTERTAINMENTS SYSTEMS: SERVICING & REPAIRS I am stuck on How to check for a "hot chassis" TV. Does one first place an isolation transformer between the wall outlet and the equipment, ground the chassis to earth? if that be it, what do I then do to ascertain whether the equipment is a "hot chassis"?
 

MrChips

Joined Oct 2, 2009
30,620
1. Check for absence of power transformer.
2. Check for low resistance between the chassis and one of the prongs on AC plug.
3. Plug in and turn on TV. Check for AC voltage between chassis and Safety GND. Reverse AC plug and check again.

Do all of the above.
 

thatoneguy

Joined Feb 19, 2009
6,359
You can also get one of them $15 wands that will alert you when > 50V AC/DC is present and wave it around the board to find the "hot" area.

The chassis should be tied to the green wire (ground) when plugged in, so you should measure some voltage between Black (hot) and ground, and even some voltage between white (neutral) and ground, though not much.

This is assuming US wiring.

If it is an LCD/LED/Plasma, the dangers aren't in the same magnitude as CRT Televisions, which would store tens of thousands of volts just waiting for you to put a probe in the wrong spot.
 
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