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SMD code NB in SOD-123F

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 38 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • ATV02W800B-HFSOD-123FTVS diode, 2 pins, ComchipTVS diode2 pinsComchip
    What it is
    TVS diode
    Maker
    Comchip
    Package
    SOD-123F
    Pins
    2
    Details
    80 V 200 W bidirectional TVS diode
    Source
    Manufacturer datasheet

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

  • BZT52C6V8-FLSOD-123FZener diode, 2 pins, Formosa MicrosemiZener diode2 pinsFormosa Microsemi
    What it is
    Zener diode
    Maker
    Formosa Microsemi
    Package
    SOD-123F
    Pins
    2
    Source
    Manufacturer datasheet

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

  • BZT52C6V8-FL-Q1SOD-123FZener diode, 2 pins, Formosa MicrosemiZener diode2 pinsFormosa Microsemi
    What it is
    Zener diode
    Maker
    Formosa Microsemi
    Package
    SOD-123F
    Pins
    2
    Source
    Manufacturer datasheet

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

  • BZT55C6V8SOD-123FZener diode, 2 pins, Formosa MicrosemiZener diode2 pinsFormosa Microsemi
    What it is
    Zener diode
    Maker
    Formosa Microsemi
    Package
    SOD-123F
    Pins
    2
    Source
    Manufacturer datasheet

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

  • KDZV6.2BSOD-123FZener diode, 2 pins, ROHMZener diode2 pinsROHM
    What it is
    Zener diode
    Maker
    ROHM
    Package
    SOD-123F
    Pins
    2
    Source
    Manufacturer datasheet

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

  • KDZVTF6.2BSOD-123FZener diode, 2 pins, ROHMZener diode2 pinsROHM
    What it is
    Zener diode
    Maker
    ROHM
    Package
    SOD-123F
    Pins
    2
    Details
    Zener Diode (AEC-Q101 qualified)
    Source
    Manufacturer datasheet

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

  • SMF80CASOD-123FTVS diode, 2 pins, SOCAYTVS diode2 pinsSOCAY
    What it is
    TVS diode
    Maker
    SOCAY
    Package
    SOD-123F
    Pins
    2
    Source
    Manufacturer datasheet

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

  • TV02W800B-HFSOD-123FTVS diode, 2 pins, ComchipTVS diode2 pinsComchip
    What it is
    TVS diode
    Maker
    Comchip
    Package
    SOD-123F
    Pins
    2
    Details
    80 V 200 W bidirectional TVS diode
    Source
    Manufacturer datasheet

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

  • 7 more parts have no package on record. Nothing rules them out, so they stay.
    • 2SCR512RNPN transistor, ROHMNPN transistorNot recordedROHM
      What it is
      NPN transistor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      NPN 2.0A 30V Middle Power Transistor
      Source
      Manufacturer datasheet

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

    • ESDBNB5V0A1ESD protection diode, JSCJESD protection diodeNot recordedJSCJ
      What it is
      ESD protection diode
      Maker
      JSCJ
      Package
      Not recorded
      Pins
      Not recorded
      Details
      ESD protection diode, VRWM 5 V
      Source
      Manufacturer datasheet

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

    • KRC402EDigital transistor (NPN, resistors built in), KECDigital transistor (NPN, resistors built in)Not recordedKEC
      What it is
      Digital transistor (NPN, resistors built in)
      Maker
      KEC
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • KRC402VDigital transistor (NPN, resistors built in), KECDigital transistor (NPN, resistors built in)Not recordedKEC
      What it is
      Digital transistor (NPN, resistors built in)
      Maker
      KEC
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • KRC652EDigital transistor (NPN, resistors built in), KECDigital transistor (NPN, resistors built in)Not recordedKEC
      What it is
      Digital transistor (NPN, resistors built in)
      Maker
      KEC
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • KRC652UDigital transistor (NPN, resistors built in), KECDigital transistor (NPN, resistors built in)Not recordedKEC
      What it is
      Digital transistor (NPN, resistors built in)
      Maker
      KEC
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • KRC852EDigital transistor (NPN, resistors built in), KECDigital transistor (NPN, resistors built in)Not recordedKEC
      What it is
      Digital transistor (NPN, resistors built in)
      Maker
      KEC
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

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.

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.

NPN transistor

Diode range, part lifted or its base leg off the pad.

Working, it reads

Red probe on the base reads about 0.6 to 0.75 V to the emitter and to the collector, and open the other way round. Collector to emitter reads open both ways.

Dead, it reads

  • Collector to emitter the same both ways, near 0 V with a continuous beep: shorted. The commonest failure.
  • The base the same both ways to another pin, near 0 V or a middling value: a shorted junction.
  • Only one junction reads, or none: a junction has failed open. It then looks like a diode.
  • A reading the wrong way round, where it should be open: 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 pair of diodes with a common pin reads just like a transistor, and some transistors carry a built-in diode or resistor. The datasheet says which.

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.

Printed with a code easy to misread as NB

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

Codes not listed here are printed on 1 more part.

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