Repair ZP120

Ando, did you get the voltages coming from the riser board to the logic board?

If you mean the 1.5V from the buck converter, yes I am getting that. Here is the post from a while ago: https://en.community.sonos.com/advanced-setups-229000/repair-zp120-17442/index5.html#post16189903

No I meant the voltages at the riser board connector with the logic board removed.

Ah I see. Sorry I have not checked for any voltages here before. Where should I check and what values should I expect?

The idea is to make sure your non functioning logic board is getting the bias it is expecting. We can compare what you read to what my working riser card is delivering. So check all the riser card output pins to chassis.

Hey gruv2ths. Sorry I haven't been on in a while. Work has been nuts and getting ready for vacation. I actually screwed up the other day when I was taking some voltage measurements and accidentally touched 2 pins on the PWM when it was powered on. I saw a small spark but no smell/smoke, however now I do not have the bias voltages on the secondary any more. I checked the fuse hoping it was just that but no go. I am really not sure I want to keep going on this as I am not sure I can bring this amp back to life. Have you made any progress with the other amps that you were troubleshooting?

Hey Ando,
No luck but no time to mess with them.
Check the 10 ohm resistor. It is axle leaded and 2 W and on top of the board.
If it reads 10 ohms then replace the PWM again.
That SHOULD get you back in the road.

I hope this thread is not dead.

I just got a ZP120 that can't power on. I have tracked down the main power transformer is dead: the primary windings are broken: from 1(RTN) to 2 is OL, 3(RTN) to 4 is 1.8ohm (this is the only good one), 3 to 5 is OL. Due to this problem, all secondary outputs are 0V.
I am wondering if the transformer part can be purchased anywhere. Otherwise I am open to other alternative Solutions like external power supplies?

I hope this thread is not dead.

I just got a ZP120 that can't power on. I have tracked down the main power transformer is dead: the primary windings are broken: from 1(RTN) to 2 is OL, 3(RTN) to 4 is 1.8ohm (this is the only good one), 3 to 5 is OL. Due to this problem, all secondary outputs are 0V.
I am wondering if the transformer part can be purchased anywhere. Otherwise I am open to other alternative Solutions like external power supplies?

Did you remove the transformer and check it? The only way to really know is to test it off the board. Transformers are tough to go bad...it takes a lot to blow one.

If you did test it off board, there usually is a number on the transformer. You may be able to go to Alibaba and search for the number/MFR to try to get a match. The other option is to get the size and windings (i.e. the specs) and try to get a replacement. If its the main Xformer, then that can be fairly standard as its a step down to generic voltages. You may be able to determine the windings from the front side voltages to the secondaries based on the output voltage (i.e. 120v to 3.3v == 120/3.3 ~ 36:1 winding, so on and so forth). You can also reach out to the MFRs and state the input/output voltages, and they can usually find one for you. You would need to give them the size... maybe some pics, etc.

Final option is look for a ZP120 on eBay that is dead as a door nail and try to get it for $20 for parts.

I hope this thread is not dead.

I just got a ZP120 that can't power on. I have tracked down the main power transformer is dead: the primary windings are broken: from 1(RTN) to 2 is OL, 3(RTN) to 4 is 1.8ohm (this is the only good one), 3 to 5 is OL. Due to this problem, all secondary outputs are 0V.
I am wondering if the transformer part can be purchased anywhere. Otherwise I am open to other alternative Solutions like external power supplies?

Not dead... nobody has had anything broken or came back :-)

Did you test that transformer off board? That's critical as being on board can give you different numbers depending on the circuit or if something is blown/shorted. Transformers do not blow very often and are fairly stable. Take a really good look at it off board and see if you see any evidence of charred marks or something if it registers bad. If it registers good, then its something else and you will need to do a bit more detective work.

If you are 100% sure its the transformer, you usually can find a number or code on it. You can search for that on Alibaba or reach out to some of the Chinese transformer manufacturers and see if they can find it. If not, you have the input and output voltages, so you can can give that to them as well to see if they can get a match. You can generally determine the winding ratio by dividing the input by the output... i.e. 120v to 3.3v = 120/33 ~ 36:1 winding for step down. You will need to calculate that for each input/output. You could also unwind it yourself and get an accurate winding count. Since its the main transformer, its a reasonable chance that its standard. If you can get the MFR, you can always contact them and they should have them on hand. However, there is a chance its a custom wind, and you would need to reverse engineer those windings yourself.

The last possibility is check eBay for a seriously bad ZP120 and see if you can grab it for $20 and just pull the transformer out of there.