Hi All,

My daughters Logitek PC speakers are suffering from warranty expiration (I don't know if she's kept the receipt anyway).

There is a "Subwoofer" (4" speaker in a 6" cube) and a pair of satelite tweeters.

Also in the box is a switchmode PSU (dead) and and all the other gubbins on a single board including an amp on a chip.

Any ideas what the output of the PSU should be?

I am thinking maybe 5V at around an amp or two, or 12V at around an amp or two.

I can try with a 5V and work up from there, but I thought i'd check here in case anyone has the definitive answer, or a very good guess (maybe amps always need 12V??)

TIA

Chris

In article ,
wrote:
Any ideas what the output of the PSU should be?

I am thinking maybe 5V at around an amp or two, or 12V at around an amp
or two.

What is the voltage rating of the reservoir caps?

--
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Dave Plowman London SW
To e-mail, change noise into sound.

On Mon, 29 Jul 2013 10:42:23 +0100, Dave Plowman (News) wrote:

I am thinking maybe 5V at around an amp or two, or 12V at around
an amp
or two.

What is the voltage rating of the reservoir caps?

And the total RMS rating of the amp and the speaker impedances. Might
give a (very) vauge clue as to how much current/voltage is required,

--
Cheers
Dave.

The caps adjacent to the output of the PSU?

16V

In article ,
wrote:
The caps adjacent to the output of the PSU?

16V


Likely 12v, then.

--
*What am I? Flypaper for freaks!?

Dave Plowman London SW
To e-mail, change noise into sound.

Can you not get spares for this psu then? Often power amps run on higher
voltages, so don't be surprised if its up to 35 volts. I'm assuming the psu
is inside the woofer box, which means you cannot replace it unless you know
the type. Currents can be quite high, particularly for small sub woofers as
they tend to have longer throws and ported cabinets.

Often though it is just a stupid bridge rectifier which goes blowing a fuse.

Brian

--
From the Sofa of Brian Gaff Reply address is active
wrote in message
...
Hi All,

My daughters Logitek PC speakers are suffering from warranty expiration (I
don't know if she's kept the receipt anyway).

There is a "Subwoofer" (4" speaker in a 6" cube) and a pair of satelite
tweeters.

Also in the box is a switchmode PSU (dead) and and all the other gubbins
on a single board including an amp on a chip.

Any ideas what the output of the PSU should be?

I am thinking maybe 5V at around an amp or two, or 12V at around an amp or
two.

I can try with a 5V and work up from there, but I thought i'd check here
in case anyone has the definitive answer, or a very good guess (maybe amps
always need 12V??)

TIA

Chris

On Tuesday, 30 July 2013 08:58:06 UTC+1, Brian Gaff wrote:
Can you not get spares for this psu then? Often power amps run on higher voltages, so don't be surprised if its up to 35 volts. I'm assuming the psu is inside the woofer box, which means you cannot replace it unless you know the type. Currents can be quite high, particularly for small sub woofers as they tend to have longer throws and ported cabinets. Often though it is just a stupid bridge rectifier which goes blowing a fuse. Brian -- From the Sofa of Brian Gaff Reply address is active wrote in message ... Hi All, My daughters Logitek PC speakers are suffering from warranty expiration (I don't know if she's kept the receipt anyway). There is a "Subwoofer" (4" speaker in a 6" cube) and a pair of satelite tweeters. Also in the box is a switchmode PSU (dead) and and all the other gubbins on a single board including an amp on a chip. Any ideas what the output of the PSU should be? I am thinking maybe 5V at around an amp or two, or 12V at around an amp or two. I can try with a 5V and work up from there, but I thought i'd check here in case anyone has the definitive answer, or a very good guess (maybe amps always need 12V??) TIA Chris

It's possible I could get spares Brian, but not easily, and also I don't have sufficient knowledge of electronics to fault find. Also a lot of it is SMT, and i've no rework facilities. but I do have a number of dead wall warts and laptop PSUs, so if I can find something that will drive the remaining electronics, that will be a quick cheap and simple fix.

In article ,
Brian Gaff wrote:
Can you not get spares for this psu then? Often power amps run on higher
voltages, so don't be surprised if its up to 35 volts. I'm assuming the
psu is inside the woofer box, which means you cannot replace it unless
you know the type. Currents can be quite high, particularly for small
sub woofers as they tend to have longer throws and ported cabinets.

Cheap lowish powered amps like these are often 12 volts as they can make
use of cheap and plentiful circuits designed for car use.

--
*I went to school to become a wit, only got halfway through.

Dave Plowman London SW
To e-mail, change noise into sound.

On Tue, 30 Jul 2013 01:12:55 -0700 (PDT), wrote:

I do have a number of dead wall warts and laptop PSUs, ...

Dead ones won't be any better than the PSU you have. B-)

Close examination of the board markings might reveal a rail voltage
but if it's all one board possibly not. Or look up the amplifier chip
part number and see what the makers application sheet uses. The
chances are the OEM won't have done much more than copy that.

--
Cheers
Dave.

Not done a full road test yet, but 12V seems to have done the trick (and I did find the details of one of the amps on badcaps, looked up the spec and that seemed to indicate 12V was good too

Thanks all

On Tuesday, July 30, 2013 8:58:06 AM UTC+1, Brian Gaff wrote:
wrote in message
...

Hi All,
My daughters Logitek PC speakers are suffering from warranty expiration (I
don't know if she's kept the receipt anyway).
There is a "Subwoofer" (4" speaker in a 6" cube) and a pair of satelite
tweeters.
Also in the box is a switchmode PSU (dead) and and all the other gubbins
on a single board including an amp on a chip.
Any ideas what the output of the PSU should be?
I am thinking maybe 5V at around an amp or two, or 12V at around an amp or
two.
I can try with a 5V and work up from there, but I thought i'd check here
in case anyone has the definitive answer, or a very good guess (maybe amps
always need 12V??)
TIA
Chris

Can you not get spares for this psu then? Often power amps run on higher
voltages, so don't be surprised if its up to 35 volts. I'm assuming the psu
is inside the woofer box, which means you cannot replace it unless you know
the type. Currents can be quite high, particularly for small sub woofers as
they tend to have longer throws and ported cabinets.
Often though it is just a stupid bridge rectifier which goes blowing a fuse.
Brian

35v into a 4" speaker? No. Not a chance in hell.


NT

On 10/08/13 19:21, wrote:
On Tuesday, July 30, 2013 8:58:06 AM UTC+1, Brian Gaff wrote:
wrote in message
...
Hi All,
My daughters Logitek PC speakers are suffering from warranty expiration (I
don't know if she's kept the receipt anyway).
There is a "Subwoofer" (4" speaker in a 6" cube) and a pair of satelite
tweeters.
Also in the box is a switchmode PSU (dead) and and all the other gubbins
on a single board including an amp on a chip.
Any ideas what the output of the PSU should be?
I am thinking maybe 5V at around an amp or two, or 12V at around an amp or
two.
I can try with a 5V and work up from there, but I thought i'd check here
in case anyone has the definitive answer, or a very good guess (maybe amps
always need 12V??)
TIA
Chris
Can you not get spares for this psu then? Often power amps run on higher
voltages, so don't be surprised if its up to 35 volts. I'm assuming the psu
is inside the woofer box, which means you cannot replace it unless you know
the type. Currents can be quite high, particularly for small sub woofers as
they tend to have longer throws and ported cabinets.
Often though it is just a stupid bridge rectifier which goes blowing a fuse.
Brian
35v into a 4" speaker? No. Not a chance in hell.
35v is only a peak current of about 4A into a 4ohm speaker and well with
a decent one perfectly fine However decent is not what you get in most
pc speakers.


most PC amps are however 12v ones using ubiquitous car stereo chipsets.

probably 5W max.

NT


--
Ineptocracy

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