I am very much a novice in electronic repair but am keen to learn but I’ve drawn a blank in fixing my Sonos connect so looking for help. After removing the power board I could tell the fuse had blown and a NTC thermistor had failed. I also suspected capacitor C206 (1800uF, 6.3V) which appeared to have bulged top. I do not see any other signs of distress so I replaced all of these components and upon power up the fuse immediately blew.

So there is clearly something wrong/shorted downstream of the earlier failed parts thermistor & fuse and need some advice what I can check. I have searched unsuccessfully to find schematics but have read many other posters that have successfully repaired their Sonos connect after a power surge. Most others were successful in replacing the exact same components I’ve replaced so what I can check next? Pictures of my power board are attached.

 

Hard to see much from photos and I do not know power supplys well but you could check that so-8 IC there for a short and check those diodes. If they are ok its probably the transformer. Maybe one of the guys who know power supplys will chime in and lead you a little better.

 

It's a switchmode psu, and it's probably blown the chip (pins 1, 2 shorted) fuse, thermistor, on the output is just a diode, capacitor and opto-coupler and TL431 zener for regulation.

This is the chip and a typical circuit diagram...

 

It's a switchmode psu, and it's probably blown the chip (pins 1, 2 shorted)

I checked the chip, Fairchild 5M0165R, for shorts across pins; 1/6/7/8 (drain) to 2 (GND) & is open circuit. I looks difficult but not impossible to desolder from board but if its open circuit does that indicate its not the problem source? I'm going to make a dim bulb tester to see if I can run the circuit without blowing the fuse and see if I can detect any components getting hot? Any other advise on what I can do/check?

 

All i can suggest is replace the mosfet, chip, and check any other silicon parts D2, looks like you have removed a few ...

 

The bridge rectifier is also another possible cause for blowing fuses. Check that none of the 4 diodes in the bridge rectifier are shorted.

Les.

 

The bridge rectifier is also another possible cause for blowing fuses. Check that none of the 4 diodes in the bridge rectifier are shorted.

Les.

Yep just tested MB8S bridge rectifier and its shorted. Thanks.

 

Need to be careful using a DBT or other limiter or soft start when testing a SMPS. One of the features of a SMPS is that if the input voltage is low, it will just draw more current to supply the needed output. It is effectively a negative resistance. As such it can be made to oscillate quite easily if you try to moderate the input current/voltage.

 

I appreciate all the prior posts as I was quite disappointed when my Sonos failed a few months ago.
When I cracked it open and measured the voltage it was clearly due to a failed power board.

Initially I was going to attempt to rework the power board but was finding it difficult identifying and locating the original board components. Fortunately, I was able to locate two small form-factor AC to DC power supplies for ~ $9 a piece. I carefully soldering them in and am happy to report that my Sonos lives again!

Along the way, I took a couple of photos to document the process and just added some rework instructions to the attached PDF file. If you are reasonable confident with a soldering iron and NOT ham-fisted it should be a breeze.

 

I appreciate all the prior posts as I was quite disappointed when my Sonos failed a few months ago.
((snip))
Along the way, I took a couple of photos to document the process and just added some rework instructions to the attached PDF file. If you are reasonable confident with a soldering iron and NOT ham-fisted it should be a breeze.

Hello and thanks for the great repair info!
Revisiting this post from my position in the future, I was wondering how your repair solution has held up?
I was also wondering if, having circumvented the old power supply, you could have just removed the malfunctioning board to make more room for the new power supplies?
Thanks again for sharing your work with the rest of us.
JustaJ0e

 

I appreciate all the prior posts as I was quite disappointed when my Sonos failed a few months ago.
When I cracked it open and measured the voltage it was clearly due to a failed power board.

Initially I was going to attempt to rework the power board but was finding it difficult identifying and locating the original board components. Fortunately, I was able to locate two small form-factor AC to DC power supplies for ~ $9 a piece. I carefully soldering them in and am happy to report that my Sonos lives again!

Along the way, I took a couple of photos to document the process and just added some rework instructions to the attached PDF file. If you are reasonable confident with a soldering iron and NOT ham-fisted it should be a breeze.

Thanks to WAHanley for very god alternative.

My SONOS Connect didn’t stop completely, I lost contact with it, but I came on again after e cooling period and worked for a day, then it had fast flickering red light.

As it turned out the 14V was 17V, the Zener was open.

Replacing the Zener brought back 14V. Correct measuring without load, but connected the 3.3V was merely 2V.

Tried to load it with 12r (aprox. 0.275A) still only 2V. Gave up on figuring out the

current control.

Then I followed WAHanley example, bought the 2 power suplyes and a IEC C8 connector, found at piece of VeroBoard and replaced all power supply.

It playes for me right now

 

Hi I looked for the PSUs recommended but could not locate them - also they looked expensive. So I bought a 15V and a 3V power supply from Amazon and wired these onto the cables shown on the pdf document - these worked fine and probably more reliable than the Sonos one which seems to be prone to failure!. I have to have to 13A sockets now though...! See photo