Repair ZP120

Well d16010 would not make it not work at all. It is the rectifier for the 15V rail I believe. If you haven't confirmed, I would check Vpri and Vmid with reference to Pgnd. If you are getting around 150V and 300V you are good, I would also pull the datasheet for the PWM U16002 (KA5M0265R ) and and make sure that you are getting the Drain voltage and primary ground on the input pins. If you are getting them both, you outta replace the PWM.

The opto may be toasty.
The opto is the 4 pin ic that crosses the white boundary of isolation. The LED aside should read about a volt or so in slide mode, the bjt side should read a open. Do this testing with no power applied. I am pretty sure it’s the part circled in yellow. Pull the datasheet.

I tested the opto not sure if i did it right I used two DMs and connected them at the same time, there was no continuity at all when tested in diode mode on pins 3and 4 either way.

I opened up a non-functioning ZP120. The image shows what I found (it looks like a damaged capacitor to me). This is located just downstream of the rectifier. I looked at other images in this thread, and (while it's hard to tell), none of them seem to show a capacitor in this location -- I wonder if this was somehow dislodged from elsewhere and landed in the right place to blow the fuse?? In any event, as soon as I touched it, it dislodged from the circuit board.

In any event, I bridged the blown fuse with a 32W bulb, and the device booted up just fine (the bulb goes bright and then dims as the capacitors charge up). I get voltages on the board, although they differ slightly from the ones that gruv2ths documented.

As soon as I try to play anything I get the white-off-orange-off cycling lights. The sonos app shows the music is playing, but the volume gets reset to about 15% a few seconds after I increase it.

Coincidentally, I have another connect that has the exact same symptoms (I don't recall if it is a ZP120 or ZP100). The behaviour is the same, and I get a low level of volume on the RCA jacks from it. I have not attempted to open that one up yet.

I'm eager to get these working, and am fairly competent with electronics. I have meters and an oscilloscope and am looking for help to troubleshoot this, if anyone is able to offer help on what to look for.

timc995, see below, its a ceramic cap. No idea the PN or parameters. Looks like it is just before or in parallel with the common core inductor. Your primary side voltages may be a little different due to the bulb, it is making a voltage divider with the unit, the thing to watch is the secondary side DC voltages.
This goes for everybody troubleshooting their Sonos Amps, make sure your CPU_GND test point is shorted to the GND36 test point. In the attached picture, you will see a small yellow jumper on the bias converter transformer secondary. That jumper is makes sure the returns are connected together. They need to be.
If they are not, the 3.3V and the 8.5/15V outputs won't be grounded together which meas lots of confusion for the processor.

I think what we are seeing here with most or all of the no power fails on the Connect:AMP is the AMPs inability to handle power surges. There is no active circuit on the front end of the power supply to handle surges. The passive filter does the best it can, which sometimes is not good enough. And since every surge is different the failures are all different. I have not seen the cap you show in the picture blown before.

In looking at those two points on the circuit board (where the capacitor blew), I was measuring 278VDC. SO, I guessing that the capacitor was just a filter, I installed the largest capacitor I had that fit the space. I used two 250V 1000pF in series (so 500V 500pF equivalent). I also replaced the fuse with a 5A 250V one.

After this, I had the exact same problems when I booted it up with the 32W dim bulb. It would boot fine, but as soon as I played any music I got the white/orange flashing, and the volume would reset to about 15%.

I was able to see that the 36V test point would jump up to 36VDC then gradually drop to 15VDC over about 2-3 seconds. The fault would come on right as it dropped below about 20VDC. The 278VDC would also drop... to something well below 100VDC. I surmised that my 32W bulb just wasn't passing enough juice, so I removed it. Then the 278VDC rose to 305VDC, and all my problems disappeared. It's rock solid now, and I'm quite a happy camper.

I was even able to effect the entire repair without removing any of the circuit boards. 🙂 Thanks gruv2ths!

Now, on to the ZP100 that's been failing. That one has a bad channel. It either doesn't play from the left channel with no fault, or it throws a fault (white/orange flashing).