Hi all,
I have a sonos zip-100 which I bought off eBay. Unfortunately one channel is not working (silent). As far as I know it's a class d amp inside.
What have I done so far:
- checked if there is output in both channels rca output, which there is. This leads me to believe the digital (source) part is ok, it's the amp channel that's failing.
- hooked up the speaker terminals to the scope, using 8ohm dummy load. Both channels read an output on the scope.
I'm puzzled... there is output on the scope, but definitely the left channel fails when a speaker is hooked up. My speakers are 6ohm.
Any suggestions what to do next?
I have a sonos zip-100 which I bought off eBay. Unfortunately one channel is not working (silent). As far as I know it's a class d amp inside.
What have I done so far:
- checked if there is output in both channels rca output, which there is. This leads me to believe the digital (source) part is ok, it's the amp channel that's failing.
- hooked up the speaker terminals to the scope, using 8ohm dummy load. Both channels read an output on the scope.
I'm puzzled... there is output on the scope, but definitely the left channel fails when a speaker is hooked up. My speakers are 6ohm.
Any suggestions what to do next?
Can u make a 4ohm dummy load?
Ignoring possible "dumb" errors (e.g. connector issues, blown speaker), my first guess is the amp cannot take an inductive load anymore for some reason, possibly damaged output transistors or protection circuitry. Also check if the zobel network is working.
But really, if you can see the signal on the scope with a dummy load, further root cause isolation shouldn't be too hard.
Ignoring possible "dumb" errors (e.g. connector issues, blown speaker), my first guess is the amp cannot take an inductive load anymore for some reason, possibly damaged output transistors or protection circuitry. Also check if the zobel network is working.
But really, if you can see the signal on the scope with a dummy load, further root cause isolation shouldn't be too hard.
The built-in amplifier is class D. This implies there are 2 kinds of output:
- The "carrier residual": a steady sine wave of less than a few volts peak to peak at a few hundred khz. This indicates the power amplifier is working. It is easier to view with no audio playing, or almost no audio, but I've read somewhere that this model stops the class D amplifier when there is nothing playing, so carrier residual may stop at end of songs.
- The audio output below 20khz.
There is one type of failure where carrier residual would be present but audio won't: Audio path broken between digital signal board and amplifier board.
Otherwise I assume you have checked your speakers by swapping them to the working channel.
- The "carrier residual": a steady sine wave of less than a few volts peak to peak at a few hundred khz. This indicates the power amplifier is working. It is easier to view with no audio playing, or almost no audio, but I've read somewhere that this model stops the class D amplifier when there is nothing playing, so carrier residual may stop at end of songs.
- The audio output below 20khz.
There is one type of failure where carrier residual would be present but audio won't: Audio path broken between digital signal board and amplifier board.
Otherwise I assume you have checked your speakers by swapping them to the working channel.
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