Repair ZP120

I am still puzzled as to why your shorted diodes don't blow the fuse. Wonder if the common core inductor just before the diodes has been blown open?
Good news on your Play5, never tried to fix one. I have a Play3 that shuts down after a few minutes. That I will save for another day.

Gruv2ths,

I couldn't detect visually any cracks in the solder joints of caps on the logic board. I don't have the oscilloscope or skill to troubleshoot the noise I'm hearing. I'm an old analog guy and digital control circuits are new to me. I'll wait until I can locate another logic board to try as a replacement. If you or anyone else on the forum has a logic board they want to sell then please let me know.

Pdog,
What I meant was, look for cracked ceramic caps.
I have a spare logic board.
Will message you.

Hello gruve2ths excellent jobb back there.
I have a zp120 it goes flashing orange and white when play is pressed. I have changed the driver IC 14pin on the logic card and that broblem was solved internet connection and volume ok but still not get any sound from the speakers!! I'm not sure that i soldered all the pins from the new 14 pin IC on the logic board .... is there any chematic or can i measure it some way.

Hi Sotisg69,
Well if you’re original problem is gone but now you have a new problem, I would definitely resolder the pins of the new IC. Maybe take a magnifying glass and see if you have good solder flow on each pin, and more importantly make sure you have not bridged and pins with solder.
After that when you push play, make sure your 36V test point on the bottom of the power board goes from 15V to 36V.
If all that is ok, there is a pre-amp chip between the logic board and the power amp ICs. It has a mute pin that you can see if it is stuck. But it’s unlikely. More likely your already on the right track.

Hi Gruv2ths.
After i´m push play its still 15V at 36V testpoint?

Hi Gruv2ths,

I had some fun trying to bridge a 0.1ufd cap across some of the caps on the logic board. It's not a practical thing to do on the small package caps but the principal of the problem-solving action is sound give the noise I'm hearing. Unfortunately my efforts had no impact. I don't think it is cap filtering issue. What I did discover, however, was when I disconnected the three amp antennas from the logic board, and therefore shut down the Sonos net, the noise almost entirely disappeared. The amp was hardwired by Ethernet cable to my music server and the amp had been broadcasting to the other Sonos units. I could still hear the noise faintly but not enough to make the amp unusable which was the case before. Unfortunately I don't want to use the amp as a stand alone amplifier unconnected to a net. I then tried connecting the amp by another Ethernet cable to a Sonos bridge. The Sonos net went into action, but the noise returned which I didn't expect. I thought the Ethernet would just be an in and out connection through the amp with no impact on the noise. In any case, it appears that the issue is in the logic board and not as simple as a damaged cap.

I'm not sure whether I want to sink any more money into the amp at this point.

Another thought, since the bridge was sitting near the amp maybe that wasn't a "fair" set-up. Even with the amp's antennas disconnected, maybe the amps logic board was picking up enough wi-fi signal from the bridge to start processing the Wi-fi signal and triggering the noise issue. I've packed everything up now. Maybe tomorrow I'll try again with the amp much further away from the bridge. However, even if the logic baord stops processing a Wi-Fi signal and the noise disappears (just a theory), it still leaves me needing a new logic board.

It's all fun though!

sotisg69
Hmmm, well that's not good. The 36V is what biases the output section.
So we need the 36V.
Can you check to make sure the CPU GND test point is 0 ohms to the RTN36V test point. If not they need to be shorted together.
The controller for the 36V and the 36V gate drive circuit is on the riser card between the power and logic boards. Near the transformer on the riser board. (the transformer is part of the gate drive for he 36V supply)
That is as good a place as any to start.
Let me look at one I have and will see if I can make a test aid.