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SMD code YL-

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.

48 parts are printed YL-

Not sure which one you have?

Answer up to 4 quick questions and these 48 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • BZT52C15SOD-123Zener diode, 2 pins, VishayZener diodeSOD-1232 pinsVishay
    What it is
    Zener diode
    Maker
    Vishay
    Package
    SOD-123
    Pins
    2
    Source
    Manufacturer datasheet

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

  • BZT52C15-GSOD-123Zener diode, 2 pins, VishayZener diodeSOD-1232 pinsVishay
    What it is
    Zener diode
    Maker
    Vishay
    Package
    SOD-123
    Pins
    2
    Details
    5215 V Zener diode
    Source
    Manufacturer datasheet

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

  • LBC807-40WT1GSOT-323PNP transistor, 3 pins, LRCPNP transistorSOT-3233 pinsLRC
    What it is
    PNP transistor
    Maker
    LRC
    Package
    SOT-323
    Pins
    3
    Details
    Bipolar transistor, PNP, IC 500 mA, VCEO 45 V
    Source
    Manufacturer datasheet

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

  • NCP4587DMX18DFNLDO regulator, onsemiLDO regulatorDFNNot recordedonsemi
    What it is
    LDO regulator
    Maker
    onsemi
    Package
    DFN
    Pins
    Not recorded
    Details
    150 mA, Tri-Mode, LDO Linear Voltage Regulator
    Source
    Manufacturer datasheet

    Is it dead? The meter test is below: Voltage regulator.

  • NSR05T30XV2SOD-523Schottky diode, 2 pins, onsemiSchottky diodeSOD-5232 pinsonsemi
    What it is
    Schottky diode
    Maker
    onsemi
    Package
    SOD-523
    Pins
    2
    Details
    500 mA, 30 V Schottky Barrier Diode
    Source
    Manufacturer datasheet

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

  • S-LBC807-40WT1GSOT-323PNP transistor, 3 pins, LRCPNP transistorSOT-3233 pinsLRC
    What it is
    PNP transistor
    Maker
    LRC
    Package
    SOT-323
    Pins
    3
    Details
    Bipolar transistor, PNP, IC 500 mA, VCEO 45 V
    Source
    Manufacturer datasheet

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

  • SMAJ33CSMATVS diode, 2 pins, DOWOTVS diodeSMA2 pinsDOWO
    What it is
    TVS diode
    Maker
    DOWO
    Package
    SMA
    Pins
    2
    Source
    Manufacturer datasheet

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

  • SMZG3806BSMBGZener diode, 2 pins, VishayZener diodeSMBG2 pinsVishay
    What it is
    Zener diode
    Maker
    Vishay
    Package
    SMBG
    Pins
    2
    Details
    51 V Zener diode
    Source
    Manufacturer datasheet

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

  • SMZJ3806BSMBZener diode, 2 pins, VishayZener diodeSMB2 pinsVishay
    What it is
    Zener diode
    Maker
    Vishay
    Package
    SMB
    Pins
    2
    Details
    51 V Zener diode
    Source
    Manufacturer datasheet

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

  • TZT33CWSOT-23Zener diode, 3 pins, Taitron ComponentsZener diodeSOT-233 pinsTaitron Components
    What it is
    Zener diode
    Maker
    Taitron Components
    Package
    SOT-23
    Pins
    3
    Details
    SMD Zener Diodes (Three Terminals) - 300mW
    Source
    Manufacturer datasheet

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

  • 2SB1115-LSOT-893 pins, NEC ElectronicsNot recordedSOT-893 pinsNEC Electronics
    What it is
    Not recorded
    Maker
    NEC Electronics
    Package
    SOT-89
    Pins
    3
    Details
    Si-pnp: AF-Amp, Sw, 60V, 1A, 2W, 120MHz, B=200..400
    Source
    Published code list

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

  • 2SB1115YLSOT-893 pins, RenesasNot recordedSOT-893 pinsRenesas
    What it is
    Not recorded
    Maker
    Renesas
    Package
    SOT-89
    Pins
    3
    Source
    Published code list

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

  • 3 more parts have no package on record
    • FP6187-11X6LDO regulator, 4 pins, FitipowerLDO regulatorNot recorded4 pinsFitipower
      What it is
      LDO regulator
      Maker
      Fitipower
      Package
      Not recorded
      Pins
      4
      Details
      300mA, Low Noise High PSRR LDO Regulator
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: Voltage regulator.

    • TCM2-452AX+RF transformer, Mini-CircuitsRF transformerNot recordedNot recordedMini-Circuits
      What it is
      RF transformer
      Maker
      Mini-Circuits
      Package
      Not recorded
      Pins
      Not recorded
      Details
      RF transformer, 1000-4500 MHz
      Source
      Manufacturer datasheet

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

    • TCM2-672AX+RF transformer, Mini-CircuitsRF transformerNot recordedNot recordedMini-Circuits
      What it is
      RF transformer
      Maker
      Mini-Circuits
      Package
      Not recorded
      Pins
      Not recorded
      Details
      RF transformer, 1500-6700 MHz
      Source
      Manufacturer datasheet

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

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.

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.

Voltage regulator

Voltage, board powered, black probe on ground. Then ohms with the power off.

Working, it reads

Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.

Dead, it reads

  • Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
  • Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
  • Power off, input to output near 0 Ω: shorted.
On the board:
An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
Compare:
The same regulator on another rail or another board shows the right voltages and the right resistances.
Watch for:
Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.

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

PNP transistor

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

Working, it reads

Black 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.

Schottky diode

Diode range, part lifted or one leg off the pad. Red probe on the anode.

Working, it reads

About 0.15 to 0.45 V anode to cathode, roughly half a silicon diode, and open the other way.

Dead, it reads

  • The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
  • A reading the wrong way round as well: leaky.
  • Open both ways: failed open.
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 large Schottky can read about 0.1 V forward and beep like a short, and leaks a little the wrong way when good, more when warm. It is shorted only if it reads the same both ways. Measure it cold, beside an identical cold one.

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

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.

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.

Printed with a code easy to misread as YL-

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 27 more parts.

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