Repair ZP120



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I have had this exact thing happen but on the 36V output filter. Where is this again on the board?

I definitely would  fix that. 
just extend the wire with a small piece of wire and insulate the connection with shrink tubing. 
 

This fail means you prob either had a nick on that wire (winding) or you have a nick on the wire and a short down stream that made the nick show itself. 
Either way fix the inductor and make sure nothing is shorted. 
 

Dim bulb would help here. 

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See image...in red, on the dc output of the bridge.

Definitely looks like a nick in the wire.

I’ll report my status after I repair the inductor.

 

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ok-that what interesting, after I thought I had removed the short from the inductor I soldered it back in mounted on the bottom for evaluation, I had a pigtail 5 amp fuse and brought it up slowly with my variac and the 5 amp fuse blew. I thought I was getting a very high resistance reading between the 2 windings where there should be none, I ended up fully unwrapping the inductor and rewrapping it, put a current meter in place of a the fuse in and slowly brought the variac voltage up,watching the current draw, stayed low and got the white light on front and made it up to full voltage with no issue...now to put the inductor back in correctly and try to connect...looking real good!

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The way that coupled inductor is placed in the board layout always makes me scratch my head when troubleshooting that circuit. Is it possible when you put it back in and blew the fuse, that you had it soldered back in wrong? That would be easy to do.

Good to hear that you seem to have it on the mend!

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I thought about that and is definitely a possibility, but I don’t want to think about it because then I fully unraveled an inductor when I didn’t need too! :smile:

But, I did do a pretty good job of rewinding it .

It’s all setup and working!

I do have one heat sink clip I cant get back on, frustrating because I never needed to take it off, but there must be some special tool to spread this clip and get it over 2 transistor casings, I’ve read that it is a bear to get back on...and so far it is. 

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2 things about the heat sink clip.

  1. the Mosftet heat sink clip can EASILY bend the thin leads of the Mosfet, so be very careful. You wont know you bent the leads until the fuse blows. (the rectifier leads are much heavier and more resistant to bending) You may want to ohm out the 6 Mosfet pins after the heat sink is installed to make sure. 
  2. Believe it or not i have used a butter knife handle to spread them open and very carefully drop them down into place. Also used a half round file. If you use something abstract let us know so we can add it to the lest. LOL

 

Hi!

I just bought 2 broken Sonos amps, one is completely dead and is waiting for me to disassemble it but before I do that I need some help with the 2nd one.

 

When plugging in the power cord I can see a white light from the led then it goes off.

 

the previous owner explained what happened before it died:

“It was late one Friday evening and suddenly I only heard sound from one of the channels (mono) and I tried to remove the speaker cables by turning the knobs, and that didn’t work so I tried even harder and then the amp died. Should I mention that I was a bit drunk? I realize now that you should pull the connectors. “


any clues? I have disassembled it and didn’t see and fried components.

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Hey man,

No, that doesn’t tell you anything. 

I would check for the bias voltages. 
They must be there, that is how the led is coming on. 
maybe they only come up for a short time. 
 

Look for missing voltages. Be careful. High voltages at the input. 
 

Hey man,

No, that doesn’t tell you anything. 

I would check for the bias voltages. 
They must be there, that is how the led is coming on. 
maybe they only come up for a short time. 
 

Look for missing voltages. Be careful. High voltages at the input. 
 

Thank you, Gruv2ths! I’ll try to have a look again for any damages and then try to measure. I have been doing a lot of repair when it comes to retro video games but that’s always 12v or less so I am a bit nervous when it comes to 230v.

I figured to grab my other broken Sonos amp from storage and I didn’t notice it when I bought it but it looks like the previous owner already opened id.

The fuse was open, and the solder points looks very shady, so either he replaced the fuse or only tried doing so.

I had a pair of fuses lying around so I quickly replaced it, reassembled everything and once I plugged in the power chord my lights went out and I could smell electronic burn 🙂 xD 

Is this a case where it’s appropriate to use a bulb? A friend of mine told me to hook up a bench power supply (with very low voltage) and trace the signal from there.

All other components looked good, from the look of it.

BTW How can I figure out that the 110v/230v switch is ok and not shorted?

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