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SMD code WMs

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.

The last letter, s, is lower case, which on NXP and Philips parts is a date or factory code, so it was set aside and WM was searched.

146 parts are printed WMs

Not sure which one you have?

Answer up to 4 quick questions and these 50 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • BCR183FTSFP-3Digital transistor (PNP, resistors built in), 3 pins, InfineonDigital transistor (PNP, resistors built in)TSFP-33 pinsInfineon
    What it is
    Digital transistor (PNP, resistors built in)
    Maker
    Infineon
    Package
    TSFP-3
    Pins
    3
    Details
    Si-pnp-Digi: Sw, 50V, 100mA, 250mW, R1/R2=10k/10k, 130MHz
    Source
    Published code list

    Is it dead? The meter test is below: Digital transistor.

  • BCR183SSOT-3636 pins, InfineonNot recordedSOT-3636 pinsInfineon
    What it is
    Not recorded
    Maker
    Infineon
    Package
    SOT-363
    Pins
    6
    Details
    dual pnp dig 50V 10k+10k
    Source
    Published code list

    Is it dead? The meter test is below: This part.

  • BCR183TSOT-416Digital transistor (PNP, resistors built in), 3 pins, InfineonDigital transistor (PNP, resistors built in)SOT-4163 pinsInfineon
    What it is
    Digital transistor (PNP, resistors built in)
    Maker
    Infineon
    Package
    SOT-416
    Pins
    3
    Details
    pnp dig 50V 10k+10k
    Source
    Published code list

    Is it dead? The meter test is below: Digital transistor.

  • BCR183USOT-23-66 pins, InfineonNot recordedSOT-23-66 pinsInfineon
    What it is
    Not recorded
    Maker
    Infineon
    Package
    SOT-23-6
    Pins
    6
    Details
    equivalent 2x MPSA56
    Source
    Published code list

    Is it dead? The meter test is below: This part.

  • BCR183WSOT-323Digital transistor (PNP, resistors built in), 3 pins, InfineonDigital transistor (PNP, resistors built in)SOT-3233 pinsInfineon
    What it is
    Digital transistor (PNP, resistors built in)
    Maker
    Infineon
    Package
    SOT-323
    Pins
    3
    Details
    pnp dig 50V 10k+10k
    Source
    Published code list

    Is it dead? The meter test is below: Digital transistor.

  • BFG10SOT-1434 pins, NXPNot recordedSOT-1434 pinsNXP
    What it is
    Not recorded
    Maker
    NXP
    Package
    SOT-143
    Pins
    4
    Details
    npn 8V 250mA 1.8GHz pwr amp
    Source
    Published code list

    Is it dead? The meter test is below: This part.

  • BZT52-C20SOD-123Zener diode, 2 pins, Diodes IncorporatedZener diodeSOD-1232 pinsDiodes Incorporated
    What it is
    Zener diode
    Maker
    Diodes Incorporated
    Package
    SOD-123
    Pins
    2
    Source
    Published code list

    Is it dead? The meter test is below: Zener diode.

  • BZT52-C20SSOD-323Zener diode, 2 pins, Diodes IncorporatedZener diodeSOD-3232 pinsDiodes Incorporated
    What it is
    Zener diode
    Maker
    Diodes Incorporated
    Package
    SOD-323
    Pins
    2
    Source
    Published code list

    Is it dead? The meter test is below: Zener diode.

  • BZT52B16SOD-123Zener diode, 2 pins, PanjitZener diodeSOD-1232 pinsPanjit
    What it is
    Zener diode
    Maker
    Panjit
    Package
    SOD-123
    Pins
    2
    Source
    Published code list

    Is it dead? The meter test is below: Zener diode.

  • BZT52C16SOD-123Zener diode, 2 pins, VishayZener diodeSOD-1232 pinsVishay
    What it is
    Zener diode
    Maker
    Vishay
    Package
    SOD-123
    Pins
    2
    Source
    An older or alternative marking, from a published code list

    Is it dead? The meter test is below: Zener diode.

  • 5 more parts have no package on record
    • 74LVC1G06FS3Diodes IncorporatedNot recordedNot recordedNot recordedDiodes Incorporated
      What it is
      Not recorded
      Maker
      Diodes Incorporated
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: Inverter (ODO)
      Source
      Published code list

      Is it dead? The meter test is below: Integrated circuit.

    • 74LVC1G07FS3Diodes IncorporatedNot recordedNot recordedNot recordedDiodes Incorporated
      What it is
      Not recorded
      Maker
      Diodes Incorporated
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: Noninverting buffer/driver (ODO)
      Source
      Published code list

      Is it dead? The meter test is below: Integrated circuit.

    • AX5505R29DC-DC converterDC-DC converterNot recordedNot recordedNot recorded
      What it is
      DC-DC converter
      Maker
      Not recorded
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Micropower VFM Synchronous Step-up DC/DC Converter
      Source
      Published code list

      Is it dead? The meter test is below: Integrated circuit.

    • BCR183L3Digital transistor (PNP, resistors built in), InfineonDigital transistor (PNP, resistors built in)Not recordedNot recordedInfineon
      What it is
      Digital transistor (PNP, resistors built in)
      Maker
      Infineon
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Si-pnp-Digi: Sw, 50V, 100mA, 250mW, R1/R2=10k/10k, 130MHz
      Source
      Published code list

      Is it dead? The meter test is below: Digital transistor.

    • BD46291GVoltage supervisor, ROHMVoltage supervisorNot recordedNot recordedROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS-IC: Voltage Detector 2,9V, -Reset Push-pull output, 100ms
      Source
      Published code list

      Is it dead? The meter test is below: Integrated circuit.

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.

Integrated circuit

Voltage with the board powered; ohms from each pin to ground with it off.

Working, it reads

Supply pin at its voltage and the output doing what the datasheet says. Readings between pins depend on the part.

Dead, it reads

  • A pin near 0 Ω to ground or to the supply pin where an identical part does not read that: failed short.
  • Supply present, output stuck: failed, or its load has.
On the board:
A pin shorted to ground on the board can be anything on that net. Lift the pin to be sure.
Compare:
The surest reference is the same IC on a working board, measured pin by pin.
Watch for:
Its protection diodes can read like junctions between pins, even like a transistor. That proves nothing either way.

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

Digital transistor

Ohms range, part lifted. The datasheet gives the built-in resistors: R1 in series with the base, R2 from base to emitter.

Working, it reads

Base to emitter reads about R1 plus R2 either way round, about 20 kΩ on a 10 k and 10 k part, give or take their wide tolerance. Collector to emitter reads open. A part with no R2 reads a junction behind R1 one way instead.

Dead, it reads

  • Collector to emitter the same both ways, near 0 Ω with a continuous beep: shorted.
  • From the base, open or far above R1 plus R2: R1 has failed. Static damage shows here most often.
  • Base to emitter near 0 Ω: failed short.
On the board
this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
Compare:
The readings depend on the resistor values, so an identical part elsewhere on the board is the surest reference. Measure it the same way.
Watch for:
On the diode range a good part with 10 kΩ resistors reads open on every pair, so a good part looks dead there. Use the ohms range.

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

This part

Diode range and ohms range, part lifted.

Working, it reads

Depends on what it is. The datasheet, or an identical part, says.

Dead, it reads

  • Between two pins, the same reading both ways, near 0 V with a continuous beep: shorted.
  • Open between every pair of pins: failed open, or a part that reads open when working.
On the board
this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.

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

Zener diode

Diode range for the forward check, part lifted, red probe on the anode. A bench supply for the Zener voltage.

Working, it reads

About 0.6 to 0.8 V forward and open in reverse on the diode range. Its Zener voltage shows only on a supply: feed it through a resistor that sets about 5 mA, cathode to positive, read quickly, and it should hold near its rated voltage.

Dead, it reads

  • The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
  • Open both ways, forward too: failed open.
  • Holds well off its rated voltage on the supply test: drifted.
  • A soft knee, or a voltage that creeps on the supply test: leaky.
On the board
this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
Watch for:
A meter's diode range stops at about 2 to 3 V, so almost every Zener reads open in reverse on it, good or bad; a 3 V meter may just show a 2.4 or 2.7 V part. Above about 3 V the meter cannot tell a Zener from a plain diode.

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

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