Speakers/Subwoofer

[Buzzol]

Hello !

Recently I've been digging through some old equipment that I have and I came across my 'old' speaker set with a subwoofer 'Hercules XPS 101', which I receive as a gift approximately 6-7 years ago. I've been actively using those speakers for around 2.5 years, after which sound from the speakers, including the subwoofer disappeared, since I was quite unexperienced back then I wasn't bothering much about it, so I decided to just stash it aside until MAYBE one day I come back to it, as you can guess that day came for me!. In the meanwhile I never received any experience in audio/stereo equipment, but I guess I can say that I understand electronics pretty well, as well as the circuit boards at this point. So after reopening the subwoofer once again and closely examining if there is a burned part on the circuit board ( to places that were easily accessible with the eye) there hasn't been any obvious damage to the board. After reconnecting the equipment back to PC, sound still does not come out of speakers nor subwoofer, in fact both speakers have huge static noise and one of the speakers has sound but it appears as its really 'far' away and even at max volume it needs to be placed directly on ear to be hearable. Any advices would be helpful, since it was a gift from my brother long time ago I'd actually like to fix it and try to enjoy it once again (cause its been a while since I heard a sound as beautiful as it was from these speakers !).

P.S just figured there is a special chanell for Repairs, so please move my threat there, thank you !

 

[Harald Kapp]

Possible cause may be defect electrolytic capacitors. Check for swollen or leaking ones.
You may upload photos (<300 kB) so our members can have a look at the pcbs.

 

[Buzzol]

Possible cause may be defect electrolytic capacitors. Check for swollen or leaking ones.
You may upload photos (<300 kB) so our members can have a look at the pcbs.

Rechecked them all, and took off heat sinks and such in order to explore the rest, this is what I found, I assume this would be leakage from the capacitors?

 

[73's de Edd]

Nope. . . . .that's just being " hold down" adhesive that was sort of hap-hazardly slopped on by the manufacturer , back at assembly time.

 

[Buzzol]

Rechecked them all, and took off heat sinks and such in order to explore the rest, this is what I found, I assume this would be leakage from the capacitors?
View attachment 52080 View attachment 52081 View attachment 52082

After further examination of each one of them I found only this one that seems to be 'swallen', top is more outstanding than pointing inwards, would that indicate that this one is faulty?

 

[Harald Kapp]

It sure looks faulty. The others not being swollen doesn't necessarily mean they are good. They are the same age and the same quality. While you're at it, you could swap all of them for new ones. At least the big ones.
You need ones with the same capacity in µF and the same or higher voltage rating. Also pin pitch should match (though you can bend the pins to fit them to the existing holes). Body size doesn't matter. New ones will likely be smaller.

Also remember to apply fresh thermal paste before you add the heatsinks back.

 

[Buzzol]

It sure looks faulty. The others not being swollen doesn't necessarily mean they are good. They are the same age and the same quality. While you're at it, you could swap all of them for new ones. At least the big ones.
You need ones with the same capacity in µF and the same or higher voltage rating. Also pin pitch should match (though you can bend the pins to fit them to the existing holes). Body size doesn't matter. New ones will likely be smaller.

Also remember to apply fresh thermal paste before you add the heatsinks back.

Ok, I will get my hands on new ones and once I do I'll replace the big ones. I will try to reconnect the speakers back on and see what happens then. Gonna keep you posted after I do so and if it is going to make any changes ! Thanks for all the replies so far

 

[73's de Edd]

Those two E-caps are for that large power I.C.'s negative and positive power supply.
A progressive degree of failure of either of them would cause a proportional HUMMM to come thru the speakers and trying the volume control would be unable to quench it.

A total or significant loss of either supply voltage could cause the weak sound that you mentioned.
What is the part number on the now naked large AUDIO POWER IC ?
If you can reassemble and get all plugged in and still be able to have test meter access to those two sets of 4 diodes in front of the caps, I can give a test procedure.

 

[Buzzol]

Those two E-caps are for that large power I.C.'s negative and positive power supply.
A progressive degree of failure of either of them would cause a proportional HUMMM to come thru the speakers and trying the volume control would be unable to quench it.

A total or significant loss of either supply voltage could cause the weak sound that you mentioned.
What is the part number on the now naked large AUDIO POWER IC ?
If you can reassemble and get all plugged in and still be able to have test meter access to those two sets of 4 diodes in front of the caps, I can give a test procedure.

The 2 IC's covered in thermal paste are TDA7293, also I am able to reassemble everything back up and have it plugged in while testing with multimeter, so please guide me through test procedure if its not a problem !

 

[WHONOES]

Check the the "Mute" and "Standby" voltages on pins 9 and 10. They need to be above 3.5V for the amps to function any lower and it they will not. There will be a switch or similar somewhere on your equipment to control same.

 

[Buzzol]

It sure looks faulty. The others not being swollen doesn't necessarily mean they are good. They are the same age and the same quality. While you're at it, you could swap all of them for new ones. At least the big ones.
You need ones with the same capacity in µF and the same or higher voltage rating. Also pin pitch should match (though you can bend the pins to fit them to the existing holes). Body size doesn't matter. New ones will likely be smaller.

Also remember to apply fresh thermal paste before you add the heatsinks back.

After I finally recieved same value capacitors as the ones that looked 'faulty' I replaced them in exact same order (even used pictures to make 100% sure I am not connecting it vice-versa) after connecting it back in to electricity after around 15 seconds of being on, one of the new capacitors just blew up and I am quite unsure what the reason could be cause I bought the exact same values as the old ones and connected it in a exact same way as it was before. It was a capacitor above the 'faulty' one as shown in picture above, so it wasn't the same spot capacitor gone bad.

Check the the "Mute" and "Standby" voltages on pins 9 and 10. They need to be above 3.5V for the amps to function any lower and it they will not. There will be a switch or similar somewhere on your equipment to control same.

I'll definetly check once I can manage to run the board without any complications

 

[WHONOES]

Reasons for Electrolytic Capacitors blowing up are often reverse polarity (connected the wrong way round). Failure is usually fairly prompt in this instance. Another reason is if the rated voltage of the Cap' is significantly below the power supply voltage. In this instance failure can take much longer. Another is poor quality Chinese parts. Ripple current rating could also play a part.