Repairing Philips SPA5300/10 soundsystem

[P3trus]

I've got a problem with my Philips SPA5300/10 sound system. At random times the sound fades out, starts to sound like an old radio and then vanishes completely.

Since I don't have guarantee anymore I thought I give it a try, see if I can track down the problem and learn something. What I did so far is

• check the connectors for loose connections
• open the subwoofer to visually check the amplifier. Capacitors look fine(but they don't have to be), no loose connections either

I would guess, there is something wrong with the capacitors but it would be nice I one of the experienced users could give me a hint what could be the Problem.

Edit:

As I found out, several users have the same problem. In the official support forum (which is now offline but accessible by google cache here) they state that a specific charge had a resistor issue.

So the question is which one could it be and whats the issue?

 

[P3trus]

I inspected the PCB more carefully. I found this diode, that looks broken. It seems to have leaked on the PCB. Could this lead to such behaviour?

EDIT: I guess I was wrong, it's just the soldering flux below the diode

 

[davenn]

no its the glue that holds the component onto the so that it will stay in place during the soldering process

no idea what the resistor patch they are talking about is ??
you could always try that Philips link that was given and see if you get anywhere

Dave

 

[P3trus]

I tried to get some more information from Philips but didn't succed so far.

I checked the capacitors they are fine. I noticed that the status LED starts flickering and vanishes as well when the sound vanishes. Any suggestions?

 

[Muhammad kaleem]

Hi P3trus!
I understand its quiet some time now since you had this issue but I was wondering if u got through this issue coz I am having exactly the same problem now. and this zener diode looks faulty. Any suggestions??

Thanks

 

[shrtrnd]

We all live in different parts of the world. No one stays on this site 24/7 to respond to questions or problems. We're not ignoring you, we just can't get back to you immediately all of the time.
I don't have time right now to Google a schematic for your sound system, you might try that yourself for more information.
Someone here might eventually do it for you, but you can't sit there with a soldering iron in your hand expecting us to do it immediately.
I too would first suspect a capacitor, but your issue could also very possibly be a semiconductor problem.
Do you have, or can you get an aerosol spray can of 'freeze spray', used by elec techs to isolate heat-related problems when troubleshooting?
If your sound system cools down, and you turn it on, and everything works for a short while before the fading, it is possible the problem is a semiconductor.
When that happens, if you spray each of the power semiconductors, one at a time, you may be able to locate the problem device because the quick-cooling of that
semiconductor device will immediately return (temporarily) the sound-system to correct operation.
Is that the symptom you have?
When you first identified a possible diode problem, I could relate because a cracked diode will sometimes operate and then fail, but if your symptom is as described as
above: ie: works fine when you first turn it on, but then operation deteriorates, I'd suspect a semiconductor heat-related problem.
Don't be annoyed if nobody responds right away. Someone will get back to you when they visit this site and have an idea to help you.

 

[Georgi]

Hello,
I has the same problem and resolved it with changing two microchips rc4558 SO-8 Dual General Purpose Operational Amplifier. Now everything is OK!!!!