Mike S. wrote:
I have a dead Logitech Z-680 5.1 computer speaker system that I was
wondering about doing salvage work on, before discarding.

It consists of a subwoofer with all the amp circuitry and connectors for
the main speakers on the back, and a dedicated control pod that connects
to it using a custom wired DB9 connector.

The system stopped working and, since it was under warranty (and
discontinued), Logitech simply replaced the entire thing with the current
model (Z-5500) and does not want any of the old equipment returned. The
old and new systems are electrically incompatible, so I just boxed the
Z-680 setup and am triyng to decide what to do with it.

The electronics pod, which contains the controls, analog/digital inputs,
Dolby/dts decoders, and preamp, powers up and detects and processes input
signals appropriately. There is a power-on "thump" in all speakers when
you fire the thing up, and the sobwoofer still has a little buzz coming
out of it (that was normal), but after that ... nothing. Audio goes in,
but not out. There is a special test mode that sends tones to all speakers
for setting levels ... I hear nothing.

I'm not sure if the failure is in the pod or the main (audio) unit on the
subwoofer, though I suspect the former. I opened the pod ... lots of
surface mount chips, no visible fuses or resettable devices. Not
user-serviceable.

The subwoofer has this huge metal cage bolted on the back which contains
the audio amplifier circuits. I'm pretty sure the DB9 input on the back
contains the 6-channel preamp output from the control pod. I was thinking
of trying to send some test signals into the subwoofer's input socket, 2
pins at a time, until I figure out whether any of them elicit audio output
from the speakers. Perhaps I can salvage the subwoofer and simply hook a
line-level audio cable to whichever of the two DB-9 pins gives the desired
effect.

Comments/suggestions? Thanks.


Most of the busted speakers I've seen had mechanical problems.
Banged the volume control and broke it.
Banged the signal conector and broke it.
Dropped and cracked the circuit board.
You need either an oscilloscope or a signal injector.
mike

--
Wanted, Serial cable for Dell Axim X5 PDA.
Return address is VALID but some sites block emails
with links. Delete this sig when replying.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
htremovethistp://www.geocities.com/SiliconValley/Monitor/4710/