LG home theater in a box - film cap replacement

[moshbear]

I've had a LG home theater in a box (DVD player with integrated 5.1 receiver board) release magic smoke. Upon opening, I found that the film cap which (it looks like) decouples the + and - for the 4 ohm subwoofer channel had fried. While the 6 ohm channels used 0.47 uF 5% (474J) 63 V caps, the burnt one was also 0.47 uF 5% 63 V.

Which value should the cap for the 4 ohm channel be boosted to (capacitance and voltage) so that the probability of magic smoke is lowered?

Yes, this isn't an electrolytic, but a failed cap is a failed cap.

[tom66]

Re: LG home theater in a box - film cap replacement

0.47uF is a very small audio coupling cap! Or is it in series with a resistor for amplifier stability?

[moshbear]

Re: LG home theater in a box - film cap replacement

0.47uF is a very small audio coupling cap! Or is it in series with a resistor for amplifier stability?

Could be: there are a few SMT devices indicative of an RC chain. I'm not at home until midnight-ish, so I can't use my DMM (for continuity testing), a pen, and scrap paper to flesh out a diagram at the moment.

[budm]

Re: LG home theater in a box - film cap replacement

I believe the caps are for the LC Filter to filter output the switching frequency of the ClassD amplifier output to the speakers, very common failure in the output filter stage of the ClassD amplifier. They should be located close to a bunch of Inductors and go out to the speaker terminals if I am correct.
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