Bad caps? Phillips HiFi

[ped90]

Hi all
I have a Phillips hifi here which has intermittent sound. I can hear music through earphones with no problem. It also has a second station connected via wifi which works fine, but the main base station doesn't play music through the speakers. Sometimes absolutely nothing comes out. Sometimes it plays for varying lengths of time (from just a split second to a minute). I can't see any external signs of loose connections.
I opened it up and went straight to (or what I think is) the amp board to check the caps. None of them look bulged but there looks like a resin around all the big caps which I've not seen before - almost looks like a leak or burnt..?
Take a look at the images included. I'd love to know if it's normal or not, or if you spot anything I've missed!
Thanks in advance!!

Photos:
http://1drv.ms/1Q4sZwR

[mariushm]

Re: Bad caps? Phillips HiFi

All that black stuff around the capacitors and inductors (the black round things near the light green capacitors) was a dark white/cream silicone semi-flexible material.
As it dried out, it became black and it also started to become conductive, so it's quite possible that material causes shorts or small resistance between various components under that material.

The initial purpose of that material was to keep the large parts in place during soldering and to prevent the parts from vibrating inside the box when you play music on that unit.

My advice would be to carefully scrape that black crap away from the parts and the boards. Carefully is the word, you don't want to break those small surface mounted components.
Some acetone may help soften that material.

Once you get rid of that black crap, if you still have problems, get back to us.

[Behemot]

Re: Bad caps? Phillips HiFi

No image is loading there, please upload few images to the forums. All the image hostings are PoS.

[stj]

Re: Bad caps? Phillips HiFi

things like that could be the headfone socket switch contacts.

[ped90]

Re: Bad caps? Phillips HiFi

Thanks mariushm, very interesting! Is it common for the silicone to dry up like that? What could cause it?
Well, after a full 2 hours worth of painfully scraping and wiping with acetone (this stuff does NOT come away easily!!), I ended up breaking one of the surface mounted components clean off
So disappointing!
I've tried emailing Philips for a replacement board, but I'm pretty sure the answer will be a No!

[stj]

Re: Bad caps? Phillips HiFi

foto's of the board and part. pls
sounds fixable.

[ped90]

Re: Bad caps? Phillips HiFi

3 new photos added to original link..not sure I can solder something that small!

[nkeck72]

Re: Bad caps? Phillips HiFi

I would attempt to resolder with a fine tipped iron... the key words here are fine tipped. Another option is to bodge on a through-hole component with the same rating and make sure it doesn't short with anything. Shorted components will create a pile of burnt-silicon-smelling rubbish.

[stj]

Re: Bad caps? Phillips HiFi

well i cant see the foto's because all m$ domains are in my blocklist.
(and i'm keeping it that way on principle)