Fried Sub-Woofer. Any way i can fix it ?

[techspark]

When i powered up my pc yesterday, i heard a tuck sound from my logitech z313 sub-woofer and i saw a bright spark on my surge protector. I immediately turned everything off. Checked the surge protector, everything looked alright, no black/burnt marks seen. I then plugged everything back in , booted up my pc and everything seemed to work alright but my speakers ! I couldnt power them up. I knew the tuck sound came from the woofer, so i decided to open it up, as the warranty period has expired. When i opened it up, the pcb looked alright, but the other board, i dont know what its called, had a burnt mark. I have attached the images , please have a look and let me know whats wrong and if it can be fixed by some soldering etc.

I have a couple of questions :
1. Is there any way i can use the satellites without the sub. I am not interested in the sub anyways. I just need basic sound at the moment.
2. Is there any other used sub that i could get and make it work with my current speakers?

Thanks. Looking forward to the replies. Cheers

[redwudz]

That looks like a voltage regulator on your power supply module. Also looks suspiciously like the full AC line voltage did that. I suspect it's well beyond repair. If your PC plugs into the sub and the satellite speaker wires come out of the sub, not really worth messing with. I suspect the amplifier that feeds the satellites also blew out, along with the voltage regulator and a few other parts. Just be happy you didn't get a fire.

Unless you can find the same brand and model sub, I doubt they would be compatible. They mostly use their own type terminals and connectors, so not easy to match at times.

I'd just pick up a set of cheap powered PC speakers until you can find a decent sound setup. I use my surround amp for my PCs audio, so I gave up on computer speakers. But you can find some for a decent price online with a sub if you check around.

I would also take a closer look at your surge protector. They generally use a MOV device that self destructs on a surge or short. Most have indicator lights that turn red if the MOV blows. The bad news is most of them keep working, but with no protection.

[dragonkeeper]

Sorry man but that thing looks to be toasted. That's the amplifier board that appears to be burned, and if the satellite speakers plug into the sub the amp feeds them power as well. YOu need new speakers, waly world has some around $14 bucks that sound like crap but at least they work. I had a pair of them for about 5 yrs, i pull them out whenever I'm working on someone else's PC or if the speaker set goes out on one of my PC,s which seems to be about once a year. Which isn't bad considering i have 7 PCs in my home.

[lacywest]

I use a Pioneer VSX-815 Receiver ... Acoustic Research speakers ... 5.1 .... with a AR powered 8 inch subwoofer ... under my table on the floor.

Fronts are the AR 48S ... on the floor under my work table ... surrounds are the AR 28s ... on the backs shelves behind me

I also have two Boston Acoustics that sit up on my work table ... directly above the AR 48s speakers.

Center channel is the center channel speaker from the Acoustic Research PL 100 set ... it sits in front of my Sony 32" LCD HDTV Monitor

[techspark]

Thank you guys for the replies.

That looks like a voltage regulator on your power supply module. Also looks suspiciously like the full AC line voltage did that. I suspect it's well beyond repair. If your PC plugs into the sub and the satellite speaker wires come out of the sub, not really worth messing with. I suspect the amplifier that feeds the satellites also blew out, along with the voltage regulator and a few other parts. Just be happy you didn't get a fire.

Yeah the sub woofer goes to the pc's 3.5mm jack and the satellites go to the sub's 3.5 mm port. I am pretty sure the satellites draw power from the sub because i tried connecting them directly to my pc's 3.5mm jack , but as expected, no sound. Just curious, is there a chance the satellites have also gone bad, if so how do i test them ?

Unless you can find the same brand and model sub, I doubt they would be compatible. They mostly use their own type terminals and connectors, so not easy to match at times.

It will be difficult to find the same sub. Is it worth, if i show the sub to a local electrician, maybe he fix it to an extent that i can be able to run the satellites ? If yes, what parts are likely to be replaced and how much can the cost come up to ? I know one local guy here, he wont charge me for opening/seeing it, he will just charge me for the new parts and labour. So is it worth a try taking the sub and showing it to him ?

I would also take a closer look at your surge protector. They generally use a MOV device that self destructs on a surge or short. Most have indicator lights that turn red if the MOV blows. The bad news is most of them keep working, but with no protection.

I have learnt my lesson. The surge protector i m using of some cheap brand which i got for less than $5. I have no idea what MOV is , but my surge protector has a fuse and thats intact, it did not take any damage itself. Btw, the led indicators on my surge protector now shows 'Ground Open' instead of 'All okay' as before, but i doubt that would have affected the speakers, because my speakers power cord anyways did not have a ground pin. But is it okay if i continue to run my pc on this surge protector for a couple of days until my new surge protector arrives.(Its working fine) I am probably buying a belkin or apc one , but i hate the fact that they both lack individual switches for each outlet.

[redwudz]

It sounds like the surge protector is dead. The MOV (Metal Oxide Varistor) is like a fuse, but responds to high voltage instead of current or amperage overloads like a fuse does. It's probably not doing any protection at present. I would replace it ASAP if you have surge problems at your location.

But I should mention that PC power supplies are fairly resistant to surges or brownouts. A direct lightning strike on a power line or a 20KV AC line falling on your low voltage line will cause damage that a surge protector might have prevented.

You can have a tech look at your SW board, but I really doubt it's worth fixing. I suspect there is more damage to components than just the obvious parts of the burned board. But you could have someone take a look.

Those satellite speakers aren't powered, so they won't work without a amplifier. They may be OK, but not much use to you with your setup.

[mrtester]

This is an old thread, but this is a common issue with this Logitech Z313 and similar speakers and I suspect that a lot of people have this problem.

To repair this problem could be easy and inexpensive. The problem is that there is soldering involved and some of the connections are at mains voltages so don't attempt this if you are uncomfortable or not knowledgeable about dealing with circuits at 110/240V.

Always disconnect from the mains power by removing the plug from the socket and also disconnect all connections to the computer before opening the sub-woofer casing.

The casing contains a large speaker, an amplifier circuit and a separate power supply unit.

The first three thumbnails are pictures of the separate switching power supply unit circuit. The cheap components in these circuits fail causing the power-supply to stop working. Usually the power transistors are over-driven and short circuit on power-up as described in techsparks post. This almost always causes a surge on the mains side of the circuit which may blow the mains fuse, trip mains circuit breakers or as in techsparks case, fuse the disposable surge protector. The 12V side is isolated from this mayhem and the separate amplifier circuit is usually undamaged. It is therefore possible to repair the speakers by replacing the power supply unit. It is impractical to repair these power supply units, as can be seen from the third picture, damage to high voltage components can be wide spread and severe.

In this case it is clear that the power supply has failed. Failures may not be this dramatic and obvious so it is wise to test other parts of the system to verify that the power supply is the problem before you buy a new one.
Is the computer sound output working?
Are the cables and connectors OK?
Is the on/off switch OK?
Is the amplifier working?
The amplifier can be tested by connecting it to an external 12V power supply. The separate black and red wires at the bottom right of the first picture is the 12v output from the power supply and you can see the other end going into the amplifier at the top right of picture four. Disconnect the red and black from the power supply and connect them to you external power supply, in the right polarity, (Red + Black - ) using whatever connectors you can make work. Be careful not to confuse the joined figure 8 red & black wires going to the speaker at the bottom of picture four. You are looking for the green indicator light on. Don't run them at a high volume. The amplifier can draw about 160W which is about 12A at 12V. Most external power supplies will be wall wart type which are usually capable of less than 1A.

You can buy 12V 160W power supplies to run led lights or security systems for about $20 on the internet. There is an issue with the size of them. You can buy small form ones which will fit inside the casing but they are more expensive. The larger cheap ones may need to be mounted on the outside of the casing. They are metal cased so need to be earthed so the mains cable needs to be replaced with a three core flex. These are easy to get. Everyone I know has an old IEC cord from an old computer or monitor which you can cut the IEC end off.
You need to fix the flex to the case so it can't be pulled out and shield the mains connections from small objects and liquids. Silicone or hot-melt glue over the contacts and screw a piece of plastic over them to insulate them from accidental contact.

I repeat: DO NOT touch any part of the circuit if the mains is plugged in.

Good luck!

[redwudz]

mrtester, thanks for your comment, but we generally discourage posting in old threads (2011), as the OP has long ago moved on.

Moderator redwudz