Repair ZP120

The LED in the front come on in a second or so.
Do you have the gray ribbon from the front buttons to the logic board connected? (it connects under the wi/fi card)

Yes the grey ribbon cable is connected. So now something new is happening. I looked at the front of the amp and now have a white(ish) light. It seems a bit dim but I am not sure if that is normal. I tried resetting the amp to factory defaults using the instructions from the sonos site but the light never changes. I am really stumped now 🙂 Gotta go to bed as I have to wake up early tomorrow. I will pick this up tomorrow. Thanks again gruv2ths.

OK I am an idiot. After looking closer at my post from yesterday I am realizing that that is not a resistor that is burned out, but a capacitor (noted by the "C"15011 designation). I have not had a lot of time to sit down with the amp and think I was rushing yesterday which is why I said it was a resistor. It also explains why it was 0L when I tried to Ohm it out 😛 I suppose the next step will be to try and find the value of this cap and see if I can order one to replace it. Any ideas gruv2ths?

After some more investigation I have found that more that more than just the capacitor is blown. The three resistors beside that cap seem to be bad as well as an inductor. Closely inspecting these components showed that the markings have been burned off of the resistors as well as they show open on an OHM meter. Also the inductor seems to be open. The whole circuit seems to be surge protector for the Ethernet ports. This seems to indicate the possible cause of the failure as an unexpected surge in the network cable that was plugged into the amp. I am thinking about ordering all of these parts and replacing all of them.

@gruv2ths: Could you possibly take a picture of this circuit on your amp and post it here? The reason being is I am assuming the burned resistor values are the same as the other side (750 = 75 ohms) but I want to make sure. Also if you have any advice for me I would much appreciate it as I am bit rusty when it comes to component level troubleshooting.

Thanks,
Andy

ando1, good work. Always look for the burned out components as generally the suspected issue is near. Get those parts and get multiples because sometimes they will blow again when you give them power. So having extras is always good. The dim bulb will lower the chance they will blow again. Once you replace them... probe for significant heat. The hot part is usually the culprit.

If you take a pic we may be able to tell you the values of the components that you need.

Did you double check that inductor and does it have a number on it? The bad news is that inductors can be difficult to track down as many are custom. The good news is it really takes a lot for inductors to blow. So hopefully it’s not bad. One of mine had burn marks on it but still ran like a champ. If it has numbers then we may be able to find it. Pictures will help. I noticed for myself that getting my phone close allowed me to get s better look at the numbers.

Thanks m0untainman. I had to put this project aside for a bit as I have limited time with the holidays approaching. I will try to pick it back up soon. I am starting to think that there may be more wrong with that WiFi board than just those caps and resistors. In looking closer, the circuit seems to be a decoupling circuit to shield the GND side of the ethernet ports. Right now the behavior of teh amp is that once it is plugged into power, the LED will go straight to a very dimly lit state. Since I do not own a functioning amp, from what I read, the LED is supposed to start blinking white and then go solid once the unit has fully booted and connected. Or the LED will flash green when it is ready to be set up on a network. Either way, the dim white LED is not one of the normal function states. I am hoping to score another broken amp. possibly with a power failure or some other failure mode that I can take both broken ones and make a god functioning one. I am a bit sick thinking that I dropped $150 on this one, but I knew the risk and gambled so oh well. Hopefully it will work out in the end.

Thanks,
Andy

Don't give up too quickly. Order those parts off eBay or Aliexpress. Those parts being replaced may do it, or it may help lead to the true culprit based on what I said in my last response. Burned parts are usually close to, or the actual problem. The dim bulb tester will help you determine that.

I'm actually out of town on vacation for a couple of weeks due to the holidays, so I can't test these until I get back. I have a cap tester to get the values of the C15011 value.@gruv2ths, are you able to pull some values for ando1?