Plasma capacitor discharge time after removing power cord

[videobruce]

About how long after power being removed and all cables disconnected from the SMPS board on a Plasma set is it safe to remove that PS to test? Too be sure, what points can be checked for stray voltage that wasn't discharged?

This is a 2010 LG set if that matters.

[Alastair E]

Re: Plasma capacitor discharge time after removing power cord

Depends on whether the fault is causing the main caps to remain charged (Which is quite common in fact!)--in which case, There IS no 'safe' amount of time.

A High Quality Cap can maintain a charge Indefinitely, Certainly hours, often for days or weeks.

Treat ALL PSU high-voltage reservoir caps as Charged, unless you have checked--No Matter HOW long the set's been off.....

Believe me, Over the last 30 odd years, Ive had MANY a huge belt off a cap in various bits of kit--that hasn't seen mains to it for days--I think I'm almost immune now, but still wakes you up!.....

[tom66]

Re: Plasma capacitor discharge time after removing power cord

There is no fixed limit. People say an hour but I've had boards retain charge for longer. If you remove the board carefully (hold only the edges, secondary side only) then you may be able to measure the capacitor voltage (primary and secondary.) Discharging with a 120V lightbulb works.

[videobruce]

Re: Plasma capacitor discharge time after removing power cord

Ok, thanks.
In the past I have seen some guys just short out the pins which I never did and didn't think it was the greatest idea.
Your take?

[tom66]

Re: Plasma capacitor discharge time after removing power cord

I'd use an ordinary filament light bulb, 100W ought to do it