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SMD code WVS

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.

6 parts are printed WVS

Not sure which one you have?

Answer up to 4 quick questions and these 6 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • SMAJ85CASSMATVS diode, 2 pins, JieJieTVS diodeSMA2 pinsJieJie
    What it is
    TVS diode
    Maker
    JieJie
    Package
    SMA
    Pins
    2
    Source
    Manufacturer datasheet

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

  • BCR129SOT-23Digital transistor (resistors built in), 3 pins, InfineonDigital transistor (resistors built in)SOT-233 pinsInfineon
    What it is
    Digital transistor (resistors built in)
    Maker
    Infineon
    Package
    SOT-23
    Pins
    3
    Source
    Published code list

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

  • BCR129FTSFP-3Digital transistor (NPN, resistors built in), 3 pins, InfineonDigital transistor (NPN, resistors built in)TSFP-33 pinsInfineon
    What it is
    Digital transistor (NPN, resistors built in)
    Maker
    Infineon
    Package
    TSFP-3
    Pins
    3
    Details
    Si-npn-Digi: Sw, 50V, 100mA, 250mW, R1=10k, 150MHz
    Source
    Published code list

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

  • BCR129SSOT-3636 pins, InfineonNot recordedSOT-3636 pinsInfineon
    What it is
    Not recorded
    Maker
    Infineon
    Package
    SOT-363
    Pins
    6
    Source
    Published code list

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

  • BCR129TSOT-416Digital transistor (NPN, resistors built in), 3 pins, InfineonDigital transistor (NPN, resistors built in)SOT-4163 pinsInfineon
    What it is
    Digital transistor (NPN, resistors built in)
    Maker
    Infineon
    Package
    SOT-416
    Pins
    3
    Details
    Si-npn-Digi: Sw, 50V, 100mA, 250mW, R1=10k, 150MHz
    Source
    Published code list

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

  • BSS84AKSOT-23P-channel MOSFET, 3 pins, NexperiaP-channel MOSFETSOT-233 pinsNexperia
    What it is
    P-channel MOSFET
    Maker
    Nexperia
    Package
    SOT-23
    Pins
    3
    Details
    P-channel MOSFET, 50 V, 0.1 A
    Source
    Published code list

    Is it dead? The meter test is below: P-channel MOSFET.

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.

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.

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.

P-channel MOSFET

Diode range, part lifted. Test drain to source first, then short gate to source and test again.

Working, it reads

Red probe on the drain, black on the source: about 0.4 to 0.9 V, the body diode. Open the other way. The gate reads open to both other pins, both ways.

Dead, it reads

  • Drain to source the same both ways, near 0 V with a continuous beep, and still so after shorting gate to source: shorted. The classic failure.
  • The gate reads low to source or drain: gate shorted. Often all three pins end up shorted together.
  • No body diode at all: failed open.
On the board
the gate usually has a resistor to the source, so gate to source reads that resistor, which is not a fault. Lift a leg to be sure.
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 diode range can charge the gate enough to turn the part on, and then drain to source reads near 0 both ways on a good part. Short gate to source and test again before you condemn it.

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 WVS

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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