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SMD code Y9 in SOT-343

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

  • R3111Q591CSOT-3434 pins, RicohNot recorded4 pinsRicoh
    What it is
    Not recorded
    Maker
    Ricoh
    Package
    SOT-343
    Pins
    4
    Details
    CMOS-IC: Voltage Detector 5,9V±2.0%, Reset Open drain output
    Source
    Published code list

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

  • 14 more parts have no package on record. Nothing rules them out, so they stay.
    • NC7WP125L8Logic gate, onsemiLogic gateNot recordedonsemi
      What it is
      Logic gate
      Maker
      onsemi
      Package
      Not recorded
      Pins
      Not recorded
      Details
      TinyLogic  ULP Buffer with 3-STATE Output
      Source
      Manufacturer datasheet

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

    • ZGFM1016B-MSZener diode, Formosa MicrosemiZener diodeNot recordedFormosa Microsemi
      What it is
      Zener diode
      Maker
      Formosa Microsemi
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • ZGFM1016B-MS-Q1Zener diode, Formosa MicrosemiZener diodeNot recordedFormosa Microsemi
      What it is
      Zener diode
      Maker
      Formosa Microsemi
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • ZGFM1016B-MSTZener diode, Formosa MicrosemiZener diodeNot recordedFormosa Microsemi
      What it is
      Zener diode
      Maker
      Formosa Microsemi
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • ZGFM1016B-MST-Q1Zener diode, Formosa MicrosemiZener diodeNot recordedFormosa Microsemi
      What it is
      Zener diode
      Maker
      Formosa Microsemi
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • 74LVC1G98GFNXPNot recordedNot recordedNXP
      What it is
      Not recorded
      Maker
      NXP
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: Configurable multiple-function gate
      Source
      Published code list

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

    • 74LVC1G98GMNXPNot recordedNot recordedNXP
      What it is
      Not recorded
      Maker
      NXP
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: Configurable multiple-function gate
      Source
      Published code list

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

    • 74LVC1G98GNNXPNot recordedNot recordedNXP
      What it is
      Not recorded
      Maker
      NXP
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: Configurable multiple-function gate
      Source
      Published code list

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

    • 74LVC1G98GSNXPNot recordedNot recordedNXP
      What it is
      Not recorded
      Maker
      NXP
      Package
      Not recorded
      Pins
      Not recorded
      Details
      CMOS logic IC: Configurable multiple-function gate
      Source
      Published code list

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

    • BD46E422G-MVoltage supervisor, ROHMVoltage supervisorNot recordedROHM
      What it is
      Voltage supervisor
      Maker
      ROHM
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Voltage detector IC: 4.2V±1%, -MR, -Reset PPO, Rdt=200ms
      Source
      Published code list

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

    • BZX84C24-VZener diode, VishayZener diodeNot recordedVishay
      What it is
      Zener diode
      Maker
      Vishay
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Published code list

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

    • CGY121AInfineonNot recordedNot recordedInfineon
      What it is
      Not recorded
      Maker
      Infineon
      Package
      Not recorded
      Pins
      Not recorded
      Details
      GaAs MMIC
      Source
      Published code list

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

    • KRC842EKECNot recordedNot recordedKEC
      What it is
      Not recorded
      Maker
      KEC
      Package
      Not recorded
      Pins
      Not recorded
      Details
      NPN transistor: Dual, Sw, 50V, 100mA, 200mW, R1/R2=100k/100k
      Source
      Published code list

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

    • KRC842UKECNot recordedNot recordedKEC
      What it is
      Not recorded
      Maker
      KEC
      Package
      Not recorded
      Pins
      Not recorded
      Details
      NPN transistor: Dual, Sw, 50V, 100mA, 200mW, R1/R2=100k/100k
      Source
      Published code list

      Is it dead? The meter test is below: Bipolar 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.

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.

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.

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.

Bipolar transistor

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

Working, it reads

From the base, one probe colour 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.

Codes that begin with Y9

For a marking with its end worn or burnt off. Each code has a page of its own.

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