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SMD code D1 in SOT-223

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.

  • ACMS01P06Y-HFSOT-223P-channel MOSFET, 4 pins, ComchipP-channel MOSFET4 pinsComchip
    What it is
    P-channel MOSFET
    Maker
    Comchip
    Package
    SOT-223
    Pins
    4
    Details
    -60 V, -1.9 A P-channel MOSFET
    Source
    Manufacturer datasheet

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

  • BL6202PRSOT-223P-channel MOSFET, 4 pins, Galaxy MicroelectronicsP-channel MOSFET4 pinsGalaxy Microelectronics
    What it is
    P-channel MOSFET
    Maker
    Galaxy Microelectronics
    Package
    SOT-223
    Pins
    4
    Details
    1.9A, 60V, 1.8W, P Channel, Power MOSFETs
    Source
    Manufacturer datasheet

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

  • CMS01P06Y-HFSOT-223P-channel MOSFET, 4 pins, ComchipP-channel MOSFET4 pinsComchip
    What it is
    P-channel MOSFET
    Maker
    Comchip
    Package
    SOT-223
    Pins
    4
    Details
    -60 V, -1.9 A P-channel MOSFET
    Source
    Manufacturer datasheet

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

  • TBL6202PRSOT-223P-channel MOSFET, 4 pins, Galaxy MicroelectronicsP-channel MOSFET4 pinsGalaxy Microelectronics
    What it is
    P-channel MOSFET
    Maker
    Galaxy Microelectronics
    Package
    SOT-223
    Pins
    4
    Details
    1.9A, 60V, 1.8W, P Channel, Power MOSFETs
    Source
    Manufacturer datasheet

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

  • TQBL6202PRSOT-223P-channel MOSFET, 4 pins, Galaxy MicroelectronicsP-channel MOSFET4 pinsGalaxy Microelectronics
    What it is
    P-channel MOSFET
    Maker
    Galaxy Microelectronics
    Package
    SOT-223
    Pins
    4
    Details
    60V, P Channel MOSFETs
    Source
    Manufacturer datasheet

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

  • 10 more parts have no package on record. Nothing rules them out, so they stay.
    • 1N4148LW-CSwitching diode, SeCoSSwitching diodeNot recordedSeCoS
      What it is
      Switching diode
      Maker
      SeCoS
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • BFU610FRF transistor, 4 pins, NXPRF transistor4 pinsNXP
      What it is
      RF transistor
      Maker
      NXP
      Package
      Not recorded
      Pins
      4
      Details
      NPN wideband silicon RF transistor
      Source
      Manufacturer datasheet

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

    • BGU6005/N2RF amplifier (MMIC), 6 pins, NXPRF amplifier (MMIC)6 pinsNXP
      What it is
      RF amplifier (MMIC)
      Maker
      NXP
      Package
      Not recorded
      Pins
      6
      Details
      Low Noise Amplifier MMIC for GPS, GLONASS, Galileo and Compass
      Source
      Manufacturer datasheet

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

    • DS520-40A1Schottky diode, JSCJSchottky diodeNot recordedJSCJ
      What it is
      Schottky diode
      Maker
      JSCJ
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Schottky diode, 40 V, 0.2 A
      Source
      Manufacturer datasheet

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

    • ESDALC6V1-1BU2TVS diode, STMicroelectronicsTVS diodeNot recordedSTMicroelectronics
      What it is
      TVS diode
      Maker
      STMicroelectronics
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • GSRB520B40Schottky diode, Good-ArkSchottky diodeNot recordedGood-Ark
      What it is
      Schottky diode
      Maker
      Good-Ark
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Schottky diode, 40 V, 200 mA
      Source
      Manufacturer datasheet

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

    • MMBZ5226BWSZener diode, Taitron ComponentsZener diodeNot recordedTaitron Components
      What it is
      Zener diode
      Maker
      Taitron Components
      Package
      Not recorded
      Pins
      Not recorded
      Details
      SMD Zener Diodes (Three Terminals) - 200mW
      Source
      Manufacturer datasheet

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

    • MMSZ5226AHEZener diode, Galaxy MicroelectronicsZener diodeNot recordedGalaxy Microelectronics
      What it is
      Zener diode
      Maker
      Galaxy Microelectronics
      Package
      Not recorded
      Pins
      Not recorded
      Details
      3.3V, 500mW, Surface Mount Zener Diodes
      Source
      Manufacturer datasheet

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

    • SCS540DSTN-CSchottky diode, SeCoSSchottky diodeNot recordedSeCoS
      What it is
      Schottky diode
      Maker
      SeCoS
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • SGM8604-1XUDL6GOperational amplifier, 6 pins, SG MicroOperational amplifier6 pinsSG Micro
      What it is
      Operational amplifier
      Maker
      SG Micro
      Package
      Not recorded
      Pins
      6
      Details
      SGM8604-1/SGM8604-2 15MHz, High Output Drive, High Precision, Low Noise Operational Amplifiers
      Source
      Manufacturer datasheet

      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.

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.

Silicon diode

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

Working, it reads

About 0.5 to 0.8 V anode to cathode, and open the other way. Small switching diodes read about 0.6 to 0.7 V; large rectifiers can read a little lower.

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: failed open.
  • A reading the wrong way round as well: 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 three-pin body can hold two diodes. With a common pin they read two junctions from that pin, just like a transistor; in series they read two drops end to end. Test each pair the datasheet names.

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.

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.

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.

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.

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.

Printed with a code easy to misread as D1

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 13 more parts.

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