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SMD code KO in SOD-128

Marking codes are not standardised, and the same code is reused by unrelated makers for unrelated parts. Below is every part in our tables printed with it, and any printed with a code that is easy to misread as it, from the manufacturers' own marking tables and published code lists.

Not sure which one you have?

Answer up to 4 quick questions and these 3 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • TPSMZ6V8ATGSOD-128TVS diode, Fagor ElectronicaTVS diodeFagor Electronica
    What it is
    TVS diode
    Maker
    Fagor Electronica
    Package
    SOD-128
    Pins
    2
    Details
    Transient voltage supressor: Vrm=5.80V, Vbr=6.45..7.14V, Ipp=57A, 600W
    Source
    Published code list

    Is it dead? The meter test is below: TVS or ESD protection diode.

  • TPSMZ11ATGSOD-128TVS diode, Fagor ElectronicaTVS diodeFagor Electronica
    What it is
    TVS diode
    Maker
    Fagor Electronica
    Package
    SOD-128
    Pins
    2
    Details
    Transient voltage supressor: Vrm=9.40V, Vbr=10.5..11.6V, Ipp=38A, 600W
    Source
    Published code list

    Is it dead? The meter test is below: TVS or ESD protection diode.

  • 1 more part has no package on record. Nothing rules it out, so it stays.
    • BG3123RF amplifier (MMIC), InfineonRF amplifier (MMIC)Infineon
      What it is
      RF amplifier (MMIC)
      Maker
      Infineon
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: RF amplifier.

Is it dead? One meter test per kind

Parts of the same kind are tested the same way, so each test is here once. Each part above points to its own.

TVS or ESD protection diode

Diode range, from the protected line to ground, part lifted if you can.

Working, it reads

A one-way part reads about 0.6 to 0.8 V forward and open in reverse. A two-way part reads open both ways. Arrays with several lines read as the datasheet's diagram draws them.

Dead, it reads

  • From the line to ground, the same reading both ways, near 0 V with a continuous beep: shorted.
  • A reading both ways on a one-way part: leaky.
  • A one-way part open both ways: failed open.
On the board
, a line reading shorted to ground can be this part or anything else on that line. Lift it: if the short goes with it, it has failed.
Compare:
The same part on the next line or connector pin is the healthy reading to compare with.
Watch for:
A two-way part reads open both ways when it is good, exactly like one that has failed open. The meter cannot tell them apart; an identical part on the next line can.

A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.

RF amplifier

Voltage, board powered, on the output pin that the bias resistor or choke feeds.

Working, it reads

The output pin sits at the device voltage the datasheet gives, a few volts, below the supply.

Dead, it reads

  • Output pin at 0 V, or near 0 Ω to ground with the power off: shorted inside.
  • Output pin at the full supply voltage: open inside, no current flowing.
On the board:
Measured on the board with power on; the bias network is part of the reading.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
Watch for:
The figures depend on the part and its bias resistor. The datasheet gives both.

A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.

Printed with a code easy to misread as KO

One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.

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