Repair ZP120

The amp has no power. Is there an internal fuse for this unit?

Has anyone taken one apart?

306 replies

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.
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New PWMs and SCK 054 Thermistors finally came in from China. I replaced them and just as I thought, the PWM pulls down the voltage. Checked at 13.03V on pins 1 and 3 on the PWM 😉 Fired up the dim bulb and it went dark. Shut off the power and put the wifi cards back in. Moment of truth... fired it up again with the dim bulb... and the white LED flashed.

Waited a few minutes and opened the iPhone Sonos app. Bob is your Uncle! There it was in all its glory and works!

The Sonos lives and is revived. Total cost for replacement parts: $3.00. Total opportunity cost (I almost tossed it)... $500. Savings to fix it myself: $497.00. Priceless.

I want to personally thank @gruv2ths for the insight on this, and @chicks for the dim bulb ideas. That sent me on a Youtube and reading spree that gave me the tools and confidence to diagnose and fix the problems. Thanks for all the help!
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Thanks. I would like to share a couple of items that may help others...

I have no idea what kind of solder that Sonos uses, but it is insane. In order to get it to melt, I had to get my Hakko iron up to 900 degrees. 700 (its default) would barely get it to melt. Getting it off components was a chore. That PWM and heat sink took a good 45 minutes to get off along with about 2 feet of desoldering braid. I am surprised I didn't destroy contacts as I really had to put that iron on for a while to get that solder to move. I tried a desoldering pen too, but to no avail. The best way to get it off was keep cracking at it with desoldering braid. I would love to hear if anyone has any hacks or ways to deal with such a problem.

Also, the dim bulb was brilliant. What a great tool to build. It is critical for testing any sort of power supply to keep you from blowing more components. Without this, I would have destroyed multiple resistors and thermistors that kept blowing. I built this for about $25 and you can get the parts at HomeDepot:

This one was nice and clean to make - took about 10 minutes. This helped me trace the hot part. A 60 watt bulb seemed to do the trick for finding the failed component. I tried a 200 watt bulb and it let too much power through, so the bad components would get raging hot quickly. From my readings, the hot part is almost always the culprit for a failed component.

The best resource that I found for fixing and diagnosing power supplied is here:

The guy sells a PDF book that details everything from how to test different components to what tool to use. He has a nice chapter on a dim bulb tester. That site and doc really walks through the different sides of a power supply and what to look for. IMHO, that was invaluable.

Anyways, I really hope this helps others. This was a great learning experience and has given me the confidence to perhaps start hunting for bad Sonos products on eBay and fix em up. ;-)

Final words... I really want to encourage people to post in these forums for help. We CAN fix these things and with a great community like we have here, we can keep these things running. 🙂
Hi guys,
I have a great news to report, I found I was shorting the transformer contact after I installed the mainboard, I was really lucky nothing damaged. I isolated the contacts and guess what, the white LED turned on right after power on! It took me no time to add the zp120 to my Sonos setup and it is driving my KEF speaker replacing the Arcam:

The white box under the table is the zp120, the one one the small table is the zp90.

My next steps are to put everything together and fix the wifi antenna.

Thanks again for the help. I like this forum, I hope with my little experiences, I can help someone in the the future.
@brumster, yes those are thermistors part# SCK-054. Also hard to find here in the US.. I’ve found those on AliExpress as well.
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I put together a little procedure for removing the bias converter PWM.
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Awesome stuff! I was able to remove mine w/o removing the caps but it certainly would have been easier w/o them. One tip... the heat sink paste Sonos uses is really cheap stuff. If I didn’t know any better I would think it’s just white lithium grease. If you remove the PWM, clean it and use the arctic silver 5 thermal paste. It will distribute the heat much better.
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Hi All,

I just purchased a CONNECT: AMP from eBay. The auction description says it does not power on and I am hoping to use this thread to troubleshoot and fix it.

@m0untainman and @gruv2ths: Can you tell me where you purchased your part from?


First bust it open and find what may be bad. Follow some of the diagnostics in this thread. It can be one or multiple parts. For me it was 3 parts. A dim bulb tester is your friend and without that, expect to blow even more. The fact that it will not turn on is a semi-good thing as its a pretty decent bet its the power supply.

As for parts, you can try Mouser or Digikey. But as gruv2ths said, some of them are exotic parts and difficult to obtain in the US. The 2 places I got mine from are Aliexpress and eBay. They will likely come from China/Hong Kong/Taiwan, and expect a solid 20-30 day wait. They are all obtainable.

Feel free to ask questions here and we can try to help you on your quest to fix this.
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Well I got the STA508 removed and the short has disappeared! I am hoping that this is the cause of the failure. I found a US seller on eBay and wanted your opinion to see if this is the same part:

After PMing gruv2ths, I am going to try putting the amp back together and powering it up with the STA508 removed. He said it should power on without it if there are no other issues with the amp. I will update this thread later today with my findings!

Wish me luck and fingers crossed!
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@benbendog, Congrats... "Bob is your uncle"

Always good to hear when someone fixes it, because Sonos won't 🙂 Nice work.
Is there anyone here that is willing to repair a ZP100 or ZP120. I am on my 2nd iteration of each of these. One was replaced out of warranty by sonos (thanks), the other not. I know the end is nigh. Thanks
They are varistors. Part# TVR14241. So far, the only place I found them were on AliExpress. Your amp will work without them but I wouldn’t operate it for too long as they are there for protection.
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Hey Toden,
You probably have this fixed already, but if not the 74VLC06AD on mine was bad. You can download the datasheet and buy them from the link below. From the datasheet look at the pinouts and measure the outputs to ground and see if any are low resistance like 100 ohms or so. One of mine was, and that fixed my problem.

To anybody else, I have a repaired power board for sale on ebay. Let me know if you have trouble finding it.
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Re my ZP100...

The problem it had was that it was not getting any output on the left channel, and within the app it was detecting a fault. This fault caused it to reset the volume to low levels. This made it unusable as an AMP and also not particularly useful to use the RCA outputs. (I'm not sure -- maybe I could have set those to fixed output -- not sure).

In any event, I opened it up today and couldn't see anything wrong with it. However, during my poking around inside, I must have bridged something... I think It was from the AC to DC board to the chassis as I tried to measure the DC voltages there. There were fireworks and popping. I quickly unplugged it.

The interesting thing (to me) is that it is actually more usable now than before! I took the whole thing apart looking for blown capacitors or anything similar. The only thing I found was the both STA505 chips were quite obviously blown... they both literally had pins missing/blown off (see the image). I figured it was very dead and reassembled it to prove it. Lo and behold... It booted up the first time. Not only that, but it stopped throwing faults! There was no audio on either speaker (not surprising given the amp chips were dead). BUT... both RCA outputs were working. SO despite my boneheaded mistake, I now have a device that can at least be used as a sonos connect (no AMP).

I'll probably try to replace the AMP chips. I have two STA508s. These are the chips that are used in the ZP120, but they are pin for pin compatible with the STA505s that are used in the ZP100. I imagine that even if I am successful in replacing the AMP chips (no small task), there is a high probability that there are now other problems on that board, given the fireworks. On the other hand, the blown pins on the amps look to be only the positive and negative supply pins (4,5,6,7,12,13,14,15). If the board traces survived, maybe all the damage is isolated to the amp chips.

Have you ruled out a problem with the low pass filter (LPF) of the class D amplifier? The noise you hear may be "switching" noise leaking through the LPF...the electrolytic capacitors may need replacing.
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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.
Google Dim Bulb Tester for a simple, low cost way to protect devices that may still have issues...
I misled you. I forgot to reconnect the ribbon cable from the front panel controls! It attaches to the logic board directly below the Wi-Fi card. The controls now work fine. Your reply made me rethink what I had done. 🙂
I lifted the shield can and connected to the UART -- here is what I get.
So I don't forget the pins are vdd,rx,tx,gnd …

U-Boot 1.1.1(1-16-3-0.9), Build: 0.9

MPC8272 Reset Status: External Soft, External Hard

MPC8272 Clock Configuration
- Bus-to-Core Mult 3x, VCO Div 4, 60x Bus Freq 16-50 , Core Freq 50-150
- dfbrg 1, corecnf 0x10, busdf 3, cpmdf 1, plldf 0, pllmf 3
- vco_out 400000000, scc_clk 100000000, brg_clk 25000000
- cpu_clk 300000000, cpm_clk 200000000, bus_clk 100000000
- pci_clk 33333333

CPU: MPC8272 (HiP7 Rev 14, Mask unknown [immr=0x0d10,k=0x00e1]) at 300 MHz
Board: Sonos Wembley
DRAM test
Test complete - 1 errors, error pattern 00400000
### ERROR ### Please RESET the board ###
That's a bummer. Which Hakko do you use? I need a hot air tool. Crazy range in prices.
Remind me what your Amp was doing, or how it was failing?

I use the hakko 851 -- it is one of their pricier ones. I have nothing to compare it to, because it is all I have ever used. My amp was the blinking white light. After debug I found that it was stuck in the bootloader due to the dram memory test failing.
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On your first one getting the chassis apart is an adventure.
If there is no blinking lights, then you prob have a blown fuse and no bias converter.
Listen to m0untainman, he knows what he is talking about. Replace the blown fuse with a 110V light bulb.
Then go looking for trouble.
Have fun!
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Thanks! I just got notice the unit shipped and will be here next week. This weekend I am going to build a dim bulb tester and am planning on following Daniel's blog on disassembling the AMP. I am pretty good with soldering and have already checked out some possible part replacements on eBay.

Edit: I just found a site with some pretty good directions on building the dim bulb tester:
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I just wanted to check in saying that the CONNECT:AMP arrived over the weekend and it is in good shape. As far as I can tell it has not been opened. I plugged it in and sure enough no lights. With the holidays coming, I am going to have limited time to work on this, but I am planning on building the dim bulb tester today or tomorrow and hope to have a first look at the amp this coming weekend. I will report back what I find.

There were some smart people posting in this thread. Hoping they are still around. 

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Great work!
So this is what I was hoping was not the culprit. But all is not lost if it is, I have replaced both of these on a repair once. I will tell you the easy way to get these off if need be. Found them on eBay from a stateside seller. Lots of the pins on the one side are supposed to be shorted together, but not all.. LOL
This I have found to be very very close to how Sonos has implemented the STA508. See Figure 7 on page 7.

m0untainman and I both have removed that same common mode choke, it separates the 36V power supply from the load.
So you can narrow down where your short is. We both had a rough time getting it back in. :-)

I would have given you the same advice that m0untainman did above, 'it probably aint the magnetics'!
Well guess what, I fixed one this weekend that had both of the windings of the common mode choke in the input filter (right after the diode bridge) blown open. Consequently the of the big storage caps threw up under it's top cap. Strangely there were no shorts and the fuse was not blown.