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Surround sound.. Center and Sub channels gone

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j0nny_s

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Hello there, my Philips MMS 460 surround sound has recently got a problem..
All the satellite speakers work, except the center speaker, and the subwoofer itself doesn't sound either..

I was wondering if whether this was because it was used for quite a while the other night, on high volume. *Normally* this isn't a problem.. but I've noticed that after 3 hrs or so of constant music, the sub (also containing the amp) gets quite hot, and all the speakers distort (or have strange rippling/flappy noises coming from them...).

I've taken the sub apart already, and had a quick look for any physical signs of burnt out components etc... And I think I *may* have found the cause. A couple of the capacitors are bulging, as if they're about to pop. One of these caps has a small amount of brown substance on the top (electrolyte perhaps?).

Can anyone think of any other causes to losing the center/sub channels? If its only the caps, I will replace them with some new caps off Maplin.

Thanks
 
Obviously the first thing to do is replace the capacitors, make sure you buy 105 degree ones, the old ones are probably only 85 degrees.

If that doesn't cure it, the capacitors failing may have killed a chip?.
 
Hmm yeah, blown caps are the best case scenario... If however, we say that they have blown a chip as well, would I be able to buy one off the net, or would they be custom Philips ones?

As a side note, I'm really disappointed by the design of the sub/amp. Why have a powerful amplifier stuck inside a small closed box, with no ventilation (the bass port hardly extracts any heat..) and the WORST excuse for a heatsink I've ever seen! The chips aren't even properly mounted to it, I had to bend the metal fasteners and apply some more heat compound for a better contact :S
 
I think you blew up a cheap sound system.

I still have an American Scott FM stereo receiver that was made in about 1965 and it still works perfectly. It has gone through a lot of punishment.
 
audioguru said:
I think you blew up a cheap sound system.

Well yeah ;) that's obvious! But personally I think if it can be fixed, for the price of a few caps, it's worth fixing.
 
You might be lucky to find only the capacitors have failed, and maybe a transistor or two.
Use 105 degrees rated capacitors and fit good heatsinks properly with screws if you can.
 
No, Nigel, obviously the first thing to do is check the cable from the source device to the sub. Center and sub run on the same line cable (one is on the left channel, and the other is on the right), but i will give j0nny_s the benefit of the doubt and assume he already did that... :eek:
 
Marks256 said:
No, Nigel, obviously the first thing to do is check the cable from the source device to the sub. Center and sub run on the same line cable (one is on the left channel, and the other is on the right), but i will give j0nny_s the benefit of the doubt and assume he already did that... :eek:

You would have done that before you took it to pieces, but if you didn't you would still replace the duff capacitors first! - it's by far the most common fault these days.
 
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