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SMD code A1-

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.

202 parts are printed A1-

Not sure which one you have?

Answer up to 4 quick questions and these 50 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • BAW56-P2-HFSOT-23Switching diode, 3 pins, ComchipSwitching diodeSOT-233 pinsComchip
    What it is
    Switching diode
    Maker
    Comchip
    Package
    SOT-23
    Pins
    3
    Details
    75 V, 250 mA switching diode
    Source
    Manufacturer datasheet

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

  • BAW56,215SOT-23Switching diode, 3 pins, HXYSwitching diodeSOT-233 pinsHXY
    What it is
    Switching diode
    Maker
    HXY
    Package
    SOT-23
    Pins
    3
    Details
    Switching diode, 70 V, 0.2 A
    Source
    Manufacturer datasheet

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

  • BAW56CR-CSOT-23Switching diode, 3 pins, SeCoSSwitching diodeSOT-233 pinsSeCoS
    What it is
    Switching diode
    Maker
    SeCoS
    Package
    SOT-23
    Pins
    3
    Source
    Manufacturer datasheet

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

  • BAW56GPSOT-23Switching diode, 3 pins, ChenmkoSwitching diodeSOT-233 pinsChenmko
    What it is
    Switching diode
    Maker
    Chenmko
    Package
    SOT-23
    Pins
    3
    Details
    SWITCHING DIODE, 85 V, 0.15 A
    Source
    Manufacturer datasheet

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

  • BAW56HSOT-23Switching diode, 3 pins, Taiwan SemiconductorSwitching diodeSOT-233 pinsTaiwan Semiconductor
    What it is
    Switching diode
    Maker
    Taiwan Semiconductor
    Package
    SOT-23
    Pins
    3
    Source
    Manufacturer datasheet

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

  • BAW56LSOT-23Switching diode, 3 pins, onsemiSwitching diodeSOT-233 pinsonsemi
    What it is
    Switching diode
    Maker
    onsemi
    Package
    SOT-23
    Pins
    3
    Details
    Dual Switching Diode Common Anode
    Source
    Manufacturer datasheet

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

  • BAW56N3SOT-23Switching diode, 3 pins, CYStekSwitching diodeSOT-233 pinsCYStek
    What it is
    Switching diode
    Maker
    CYStek
    Package
    SOT-23
    Pins
    3
    Details
    110 V switching diode
    Source
    Manufacturer datasheet

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

  • BAW56SSOT-363Switching diode, 6 pins, NexperiaSwitching diodeSOT-3636 pinsNexperia
    What it is
    Switching diode
    Maker
    Nexperia
    Package
    SOT-363
    Pins
    6
    Details
    High-speed switching diode
    Source
    Manufacturer datasheet

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

  • BAW56TSOT-416Switching diode, 3 pins, onsemiSwitching diodeSOT-4163 pinsonsemi
    What it is
    Switching diode
    Maker
    onsemi
    Package
    SOT-416
    Pins
    3
    Details
    0.155A, 85V, Surface Mount Small Signal Switching Diodes
    Source
    Manufacturer datasheet

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

  • BAW56WSOT-323Switching diode, 3 pins, NexperiaSwitching diodeSOT-3233 pinsNexperia
    What it is
    Switching diode
    Maker
    Nexperia
    Package
    SOT-323
    Pins
    3
    Details
    SMD Small Signal Diodes
    Source
    Manufacturer datasheet

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

  • BAW156SOT-23Switching diode, 3 pins, LeiditechSwitching diodeSOT-233 pinsLeiditech
    What it is
    Switching diode
    Maker
    Leiditech
    Package
    SOT-23
    Pins
    3
    Details
    0.16A, 85V, Surface Mount Small Signal Switching Diodes
    Source
    Manufacturer datasheet

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

  • BB208-02SOD-523Varicap diode, 2 pins, NXPVaricap diodeSOD-5232 pinsNXP
    What it is
    Varicap diode
    Maker
    NXP
    Package
    SOD-523
    Pins
    2
    Details
    Low voltage variable capacitance diode
    Source
    Manufacturer datasheet

    Is it dead? The meter test is below: PIN diode or varicap.

  • BZX84-C75SOT-23Zener diode, 3 pins, NexperiaZener diodeSOT-233 pinsNexperia
    What it is
    Zener diode
    Maker
    Nexperia
    Package
    SOT-23
    Pins
    3
    Pinout
    • 1 anode
    • 2 not connected
    • 3 cathode
    Details
    75 V approx. ±5% voltage regulator (Zener) diode
    Source
    Manufacturer datasheet

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

  • 2 more parts have no package on record
    • BAW222Diode, InfineonDiodeNot recordedNot recordedInfineon
      What it is
      Diode
      Maker
      Infineon
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

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

    • BZX884B2V4Zener diode, Good-ArkZener diodeNot recordedNot recordedGood-Ark
      What it is
      Zener diode
      Maker
      Good-Ark
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Zener diode, VZ 2.4 V, 0.25 W
      Source
      Manufacturer datasheet

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

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.

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.

PIN diode or varicap

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

Working, it reads

About 0.6 to 0.9 V anode to cathode, 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.
  • 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 varicap that has drifted in capacitance reads normal on a meter. Only a capacitance meter or the tuning itself shows it.

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.

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