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SMD marking

A7in SOT-323

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.

Not sure which one you have?

Answer up to 4 quick questions and these 5 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • BAV99WSOT-323Switching diode, 3 pins, Nexperia
    What it is
    Switching diode
    Maker
    Nexperia
    Package
    SOT-323
    Pins
    3
    Details
    Switching diode, 75 V, 150 mA
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • DAN217USOT-323Switching diode, 3 pins, JSCJ
    What it is
    Switching diode
    Maker
    JSCJ
    Package
    SOT-323
    Pins
    3
    Details
    Switching diode, 80 V, 100 mA
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • 3 more parts have no package on record. Nothing rules them out, so they stay.
    • S1JMRectifier, Taiwan Semiconductor
      What it is
      Rectifier
      Maker
      Taiwan Semiconductor
      Package
      Not recorded
      Pins
      Not recorded
      Source
      From the manufacturer's datasheet

      Is it dead?

      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:
      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.

    • S1JMHRectifier, Taiwan Semiconductor
      What it is
      Rectifier
      Maker
      Taiwan Semiconductor
      Package
      Not recorded
      Pins
      Not recorded
      Source
      From the manufacturer's datasheet

      Is it dead?

      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:
      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.

    • TPS3831G33DQNVoltage supervisor, 4 pins, Texas Instruments
      What it is
      Voltage supervisor
      Maker
      Texas Instruments
      Package
      Not recorded
      Pins
      4
      Details
      150-nA, Ultralow Power, Supply Voltage Monitor
      Source
      From the manufacturer's datasheet

      Is it dead?

      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.

6 more parts are printed with a code easy to misread as A7

Printed with a code easy to misread

One character differs, and it is one that is easy to confuse under a lamp. The odd one out is marked on each.

  • BFP540printed ATRF transistor, Infineon

    Printed AT on the part. Easy to misread as A7. Check that character with a loupe before you order anything.

    What it is
    RF transistor
    Maker
    Infineon
    Package
    Not recorded
    Pins
    Not recorded
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • BZX884B8V2Lprinted ATZener diode, Vishay

    Printed AT on the part. Easy to misread as A7. Check that character with a loupe before you order anything.

    What it is
    Zener diode
    Maker
    Vishay
    Package
    Not recorded
    Pins
    Not recorded
    Details
    8.2 V Zener diode
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • MSMP8.5Aprinted ATTVS diode, Vishay

    Printed AT on the part. Easy to misread as A7. Check that character with a loupe before you order anything.

    What it is
    TVS diode
    Maker
    Vishay
    Package
    Not recorded
    Pins
    Not recorded
    Details
    150 W TVS diode, unidirectional
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • SMBG8.5Aprinted ATTVS diode, Vishay

    Printed AT on the part. Easy to misread as A7. Check that character with a loupe before you order anything.

    What it is
    TVS diode
    Maker
    Vishay
    Package
    Not recorded
    Pins
    Not recorded
    Details
    600 W TVS diode, unidirectional
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • TLV70725PDQNprinted ATLDO regulator, 4 pins, Texas Instruments

    Printed AT on the part. Easy to misread as A7. Check that character with a loupe before you order anything.

    What it is
    LDO regulator
    Maker
    Texas Instruments
    Package
    Not recorded
    Pins
    4
    Details
    200-mA, Low-IQ, Low-Noise, Low-Dropout Regulator for Portable Devices
    Source
    From the manufacturer's datasheet

    Is it dead?

    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.

  • VESD05A6A-HAFprinted ATESD protection diode, Vishay

    Printed AT on the part. Easy to misread as A7. Check that character with a loupe before you order anything.

    What it is
    ESD protection diode
    Maker
    Vishay
    Package
    Not recorded
    Pins
    Not recorded
    Details
    6-Line ESD Protection Diode Array in LLP75
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

17 more parts have codes that begin with A7

Codes that begin with A7

For a marking with its end worn or burnt off. Each one shows its full printed code.

  • BAS70AWprinted A72SOT-323Schottky diode, 3 pins, Panjit

    Printed A72. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

    What it is
    Schottky diode
    Maker
    Panjit
    Package
    SOT-323
    Pins
    3
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • BAS70AW-AUprinted A72SOT-323Schottky diode, 3 pins, Panjit

    Printed A72. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

    What it is
    Schottky diode
    Maker
    Panjit
    Package
    SOT-323
    Pins
    3
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • BAS70CWprinted A73SOT-323Schottky diode, 3 pins, Panjit

    Printed A73. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

    What it is
    Schottky diode
    Maker
    Panjit
    Package
    SOT-323
    Pins
    3
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • BAS70CW-AUprinted A73SOT-323Schottky diode, 3 pins, Panjit

    Printed A73. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

    What it is
    Schottky diode
    Maker
    Panjit
    Package
    SOT-323
    Pins
    3
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • BAS70SWprinted A74SOT-323Schottky diode, 3 pins, Panjit

    Printed A74. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

    What it is
    Schottky diode
    Maker
    Panjit
    Package
    SOT-323
    Pins
    3
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • BAS70SW-AUprinted A74SOT-323Schottky diode, 3 pins, Panjit

    Printed A74. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

    What it is
    Schottky diode
    Maker
    Panjit
    Package
    SOT-323
    Pins
    3
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • BAS70Wprinted A70SOT-323Schottky diode, 3 pins, Panjit

    Printed A70. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

    What it is
    Schottky diode
    Maker
    Panjit
    Package
    SOT-323
    Pins
    3
    Details
    SMD Small Signal Schottky Diodes
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • BAS70W-AUprinted A70SOT-323Schottky diode, 3 pins, Panjit

    Printed A70. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

    What it is
    Schottky diode
    Maker
    Panjit
    Package
    SOT-323
    Pins
    3
    Source
    From the manufacturer's datasheet

    Is it dead?

    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:
    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.

  • 9 more parts have no package on record. Nothing rules them out, so they stay.
    • AOZ2231CQI-01printed ATC1DC-DC converter, Alpha & Omega Semiconductor

      Printed ATC1. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

      What it is
      DC-DC converter
      Maker
      Alpha & Omega Semiconductor
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Synchronous buck regulator
      Source
      From the manufacturer's datasheet

      Is it dead?

      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.

    • AOZ2231CQI-21printed ATCPDC-DC converter, Alpha & Omega Semiconductor

      Printed ATCP. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

      What it is
      DC-DC converter
      Maker
      Alpha & Omega Semiconductor
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Synchronous buck regulator
      Source
      From the manufacturer's datasheet

      Is it dead?

      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.

    • AOZ2231CQI-23printed ATCSDC-DC converter, Alpha & Omega Semiconductor

      Printed ATCS. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

      What it is
      DC-DC converter
      Maker
      Alpha & Omega Semiconductor
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Synchronous buck regulator
      Source
      From the manufacturer's datasheet

      Is it dead?

      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.

    • TA6F12Aprinted ATPTVS diode, Vishay

      Printed ATP. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

      What it is
      TVS diode
      Maker
      Vishay
      Package
      Not recorded
      Pins
      Not recorded
      Details
      600 W TVS diode, unidirectional
      Source
      From the manufacturer's datasheet

      Is it dead?

      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:
      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.

    • TA6F12CAprinted ATPTVS diode, Vishay

      Printed ATP. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

      What it is
      TVS diode
      Maker
      Vishay
      Package
      Not recorded
      Pins
      Not recorded
      Details
      600 W TVS diode, bidirectional
      Source
      From the manufacturer's datasheet

      Is it dead?

      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:
      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.

    • TA6L12Aprinted ATLTVS diode, Vishay

      Printed ATL. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

      What it is
      TVS diode
      Maker
      Vishay
      Package
      Not recorded
      Pins
      Not recorded
      Details
      600 W TVS diode, unidirectional
      Source
      From the manufacturer's datasheet

      Is it dead?

      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:
      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.

    • TA6L12CAprinted ATLTVS diode, Vishay

      Printed ATL. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

      What it is
      TVS diode
      Maker
      Vishay
      Package
      Not recorded
      Pins
      Not recorded
      Details
      600 W TVS diode, bidirectional
      Source
      From the manufacturer's datasheet

      Is it dead?

      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:
      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.

    • TPSMA6L8.5Aprinted ATATVS diode, Diotec

      Printed ATA. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

      What it is
      TVS diode
      Maker
      Diotec
      Package
      Not recorded
      Pins
      Not recorded
      Details
      SMD Transient Voltage Suppressor Diodes
      Source
      From the manufacturer's datasheet

      Is it dead?

      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:
      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.

    • TPSMP12Aprinted ATPTVS diode, Vishay

      Printed ATP. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.

      What it is
      TVS diode
      Maker
      Vishay
      Package
      Not recorded
      Pins
      Not recorded
      Details
      400 W TVS diode, unidirectional
      Source
      From the manufacturer's datasheet

      Is it dead?

      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:
      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.

Open this in the search to correct a character or try another package.