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I’m repairing a laptop but I don’t know what value inductor to use/get. The schematic has values, I just don’t know how to interpret other than it’s a 2mm inductor. It’s labeled 5A_Z120_25M_0805_2P on a 1.35V line. Schematic

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Looks like something with 120 Ohms Impedance (z120) at 25MHz (25M) that can take 5 Amps (5A) in a 0805 Case (0805)

Close but not quite would be a Würth 742792025.

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  • \$\begingroup\$ Warm welcome to EE.SE! Excellent start! \$\endgroup\$
    – winny
    Commented Jun 4, 2020 at 21:18
  • \$\begingroup\$ The 2P might be two windings parallelled. \$\endgroup\$ Commented Jun 6, 2020 at 7:44
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I think that is just an obscure part number used by the manufacturer. This was also common practice with certain IC's used in some products. The IC's real part numbers would be sanded off, and replaced by a different kind of part number from the manufacturer of the product it was used in.

Generally, your "manufacturer-authorized" repair shops will have the decodes of the "part numbers". This is to try to keep others from being able to service these devices. So, your best bet is to look for any color-coding on the part, in order to deduce its inductance value.

Otherwise,

Your only other reference to that set of numbers, is to be found in the manufacturer's manuals or documentation (if they will let you have that information).

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  • \$\begingroup\$ This is good advice, but the part isn’t listed in the BOM unfortunately. I went with a higher current part with similar ratings too so here’s hoping. Thanks for your response. \$\endgroup\$
    – Omlethead
    Commented Jun 7, 2020 at 2:29
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  1. How do you know you have to replace the inductor? They seldom die.

  2. Watch Louis Rossman who does a lot of fixing these things live. The power chips (usually buck switching controllers) have a hard life, and often go. But I do see him replace resistors and capacitors as well. I linked to his youtube videos and did a search on inductor for you -- maybe your inductor did go. He might have done a similar repair.

  3. Sometimes he uses alcohol to see where a short is, after pumping some voltage into the board. The hot component gets dry first. That's the one to replace if your board is shorted.

  4. Somehow, juice, or coffee, or soda, often finds its way into these boards. Look for signs of this abuse for prime suspects.

  5. On the internet, buy a few laptops or motherboards of the same exact type you are fixing, and cannibalize them for good parts. If your inductor went, and you can find a dead laptop / motherboards of the same type, it should have your exact inductor, and odds are it will still be good. Good luck.

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  • \$\begingroup\$ Well, it can’t be good when a component looks like this: imgur.com/gallery/1HLcQZA I’ve seen some of Rossman’s videos too, but thanks for the advice. \$\endgroup\$
    – Omlethead
    Commented Jun 7, 2020 at 2:22
  • \$\begingroup\$ @Omlethead -- This is the only matching part I found, a power inductor with no filtering info. I'll try to figure that out if I get the time. \$\endgroup\$ Commented Jun 8, 2020 at 17:34

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