Repair ZP120

Is there any YouTube video that shows how to replace the fuse ? Pls add the link - Tnx

Is there any YouTube video that shows how to replace the fuse ? Pls add the link - Tnx
For your Information:

Hi everyone, interesting discussion but I want to make sure that anyone who gets to this thread knows not to open your Sonos products if you're looking to do any sort of replacement or repair with us.

Sonos products are not designed to be opened and repaired out in the world, and we do not provide any resources or replacement components for doing this. The warranty services for Sonos components also does not cover units that have been opened in any way.

Even if your player is outside the standard warranty time, we can probably still assist with a replacement as long as it hasn't been opened. There will likely be a fee for the replacement if it's out of warranty.

Anytime a unit fails, we want them to come back to us when possible so that we can review what happened and make adjustments if there's need.

@gruv2ths - Outstanding job. I have a SONOS ZP120 that unfortunately got wet and the power blew a 10ohm 2W resistor (R16017). I replaced it. I plugged it in and that resistor blew again... and it looks like it took out one of the SCK054 thermistors (TH16001). The thermistor was a wee bit charred however it tested 5ohms which is the normal rating. I have ordered new ones since I don't trust anything that got charred, but they will take 10-4 days to get from China... nobody sells em here in the US.

I tested the rectifier on the input side (the one clamped to the chassis) and it looks good. I tested the diodes and those look fine. All caps are looking good too. The fuse is fine... it never blew.

I am guessing the problem lies downstream from the components listed above. A couple of questions...

1 - That TO-220 you mentioned... is that the one that has a heatsink screwed into it and standing up? Do you know the code on it or type as I cannot tell.

2 - What is the secondary rectifier your are referring to? I would like to test mine to see if its checking out (or not).

If you have any recommendations, I would love to know how to any techniques are parts I should be checking on the PS board... I am thinking this is simple... but I am having a tough time narrowing it down.

Thanks!

Slight update... as I am waiting for the SCK054s from China... I decided to check everything in the path. All looked good except for the 115/220 red switch. It showed 0L on the meter at 115. I switched it to 220 and it was 0L. Switched back to 115 and had continuity. My guess is when the unit got wet, something happened to that switch and hence it made the unit look like it was supposed to be connected to 220v. I followed the trace and with 220v, it all leads to the blown resistor and thermistor. But with 115 active (continuity) it throws in a drop through the varistors and the other path meets it. Just a guess, but it appears that the 220v setting may have caused the current consumption along the resistor/thermistor path to exceed what it was normally supposed to see. That may be a red herring and I will find out when my thermistors arrive... but I thought the 220v setting running on 115v wouldn't hurt the PS...worst case it just wouldn't fire up. I'm just guessing that perhaps it does indeed have an impact on a PS.

Ok... I tested the thermistor and under heat etc and it seems to test out ok. Due to the excellent posts in this thread, I decided to put together a dim bulb tester so I would stop blowing components. Great idea...

So I decided to fire it up under the dim bulb tester after replacing the 10 ohm resistor and putting back the thermistor... and the light bulb shined brightly so I still have a short somewhere....

I cut the power and decided to test for heat. Again, that resistor was getting hot (and was saved due to the dim bulb tester).

Here is the resistor and it is hot (notice the circle labeled hot):

Anyone have ideas on how to hunt down the short?

A slight update... the choke filter in the upper left corner of that picture (the big one) has 4 wires. I think I have detected a short on it or something connected to it... between the primary and secondary, I get continuity with a resistance of 148 ohms. Could that be that the inductor has a short? Keep in mind it was DMM tested on board and I have not removed it.

The resistor that blows comes off the primary... so there seems to be a relation.

I pulled the inductor and its good.... so thats not it...

Great work documenting your troubleshooting and thought process. We will get good at this some day, maybe Sonos will hire us?? LOL JK
So the inductor in the upper left of your picture is the common mode inductor that is in series with the 28V supply.
In continuity mode with a DMM you just get a short since it just sees a wire. I once removed that inductor (it was a real pain getting all 4 wires back in) in an attempt to find out if my short was in the rectifier (2 diode packs clipped to the chassis) or the load. For me it was the load. One of my amp ICs was a short. That is the unit I am working currently. I will share a troubleshooting slide on the 28V supply when I get it working reliably.

@gruv2ths thanks for jumping in! Yes... removal of that inductor was easy... putting it back wasn't. I had to get creative and solder wire patches to get it through the hole so I could solder the leads back... took quite a while.

The dim light is indeed bright. The TO-220 package (center of my photo on the heat sink) PWM gets warm for sure. I'm guessing the short is somewhere in that area. Just need to get that piece off but I dread it since it has a lot of solder points and the heath sink. I was dreading pulling that component.

Not sure how to test a PWM... I'm guessing that will take a breadboard.

Finding this short is not easy!

The 2 RTN points on the transformer are showing 0L. I tried to short those too, but got nothing. Actually I am getting no power on the secondary winding (testing 1 and 2 for 3.3V and 3 and for for 8.4 volts, and 3 and 5 for 15v). They show nothing using a 60W bulb. Trying a150W bulb... more or less the same. I get some voltage on the primary (like 10v), but nothing on the secondary.

The PWM is warm so its the likeliest suspect at this stage. The PWM is HOT with the 150W bulb.