WhatSMD: identify an unknown SMD component

3 parts are printed A8

Not sure which one you have?

Answer up to 4 quick questions and these 3 parts are ranked, with a meter test that settles it. It works on a dead part too.

BAV19WS-GSwitching diode, Taiwan SemiconductorSwitching diodeNot recordedTaiwan Semiconductor
What it is
Switching diode
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.
Datasheetfor BAV19WS-G, opens in a new tab
BZT52C2V7KZener diode, Taiwan SemiconductorZener diodeNot recordedTaiwan Semiconductor
What it is
Zener diode
Maker
Taiwan Semiconductor
Package
Not recorded
Pins
Not recorded
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.
Datasheetfor BZT52C2V7K, opens in a new tab
TPS3831K33DQNVoltage supervisor, 4 pins, Texas InstrumentsVoltage supervisor4 pinsTexas 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.
Datasheetfor TPS3831K33DQN, opens in a new tab

6 more parts are printed with a code easy to misread as A8

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.

AONC68410printed ABMOSFET, Alpha & Omega SemiconductorMOSFETAlpha & Omega Semiconductor
Printed AB on the part. Easy to misread as A8. Check that character with a loupe before you order anything.
What it is
MOSFET
Maker
Alpha & Omega Semiconductor
Package
Not recorded
Pins
Not recorded
Details
Medium-voltage (40-400 V) MOSFET
Source
From the manufacturer's datasheet
Is it dead?
Diode range, part lifted. Test drain to source first, then short gate to source and test again.
Working, it reads
One way between drain and source reads about 0.4 to 0.9 V, the body diode, and the other way open. The gate reads open to both other pins.
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.
No body diode at all: failed open.
On the board:
On the board the gate usually has a resistor to the source, which reads as that resistor and 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.
Datasheetfor AONC68410, opens in a new tab
BAR50-02Lprinted ABPIN diode, InfineonPIN diodeInfineon
Printed AB on the part. Easy to misread as A8. Check that character with a loupe before you order anything.
What it is
PIN diode
Maker
Infineon
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 0.6 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:
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.
Datasheetfor BAR50-02L, opens in a new tab
BFP460printed ABRF transistor, InfineonRF transistorInfineon
Printed AB on the part. Easy to misread as A8. 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.
Datasheetfor BFP460, opens in a new tab
BFR460L3printed ABRF transistor, InfineonRF transistorInfineon
Printed AB on the part. Easy to misread as A8. 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.
Datasheetfor BFR460L3, opens in a new tab
BFS460L6printed ABRF transistor, InfineonRF transistorInfineon
Printed AB on the part. Easy to misread as A8. 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.
Datasheetfor BFS460L6, opens in a new tab
BZX884B2V7Lprinted ABZener diode, VishayZener diodeVishay
Printed AB on the part. Easy to misread as A8. Check that character with a loupe before you order anything.
What it is
Zener diode
Maker
Vishay
Package
Not recorded
Pins
Not recorded
Details
2.7 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.
Datasheetfor BZX884B2V7L, opens in a new tab

11 more parts have codes that begin with A8

Codes that begin with A8

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

SN74AHC1G86DBVprinted A863SOT-23-5Logic gate, 5 pins, Texas InstrumentsLogic gate5 pinsTexas Instruments
Printed A863. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
What it is
Logic gate
Maker
Texas Instruments
Package
SOT-23-5
Pins
5
Details
Single 2-Input Exclusive-OR Gate
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.
Datasheetfor SN74AHC1G86DBV, opens in a new tab
10 more parts have no package on record. Nothing rules them out, so they stay.
- AOZ1381DI-01printed AB01Load switch, Alpha & Omega SemiconductorLoad switchNot recordedAlpha & Omega Semiconductor
  Printed AB01. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  Load switch
  Maker
  Alpha & Omega Semiconductor
  Package
  Not recorded
  Pins
  Not recorded
  Details
  USB Type-C protection switch
  Source
  From the manufacturer's datasheet
  Is it dead?
  Voltage, board powered, black probe on ground.
  Working, it reads
  Switched on, the output pin sits at the input voltage. Switched off, it sits near 0 V.
  Dead, it reads
  Output at the input voltage while switched off: the pass element has shorted.
  Input present and switched on, no output: failed open, or shut down into a shorted load. Power off and measure output to ground.
  On the board:
  An output near 0 Ω to ground is usually the load. Lift the output pin to see which.
  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 pinout and whether the enable is active high or low differ between parts. 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.
  Datasheetfor AOZ1381DI-01, opens in a new tab
- AOZ1381DI-02printed AB02Load switch, Alpha & Omega SemiconductorLoad switchNot recordedAlpha & Omega Semiconductor
  Printed AB02. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  Load switch
  Maker
  Alpha & Omega Semiconductor
  Package
  Not recorded
  Pins
  Not recorded
  Details
  USB Type-C protection switch
  Source
  From the manufacturer's datasheet
  Is it dead?
  Voltage, board powered, black probe on ground.
  Working, it reads
  Switched on, the output pin sits at the input voltage. Switched off, it sits near 0 V.
  Dead, it reads
  Output at the input voltage while switched off: the pass element has shorted.
  Input present and switched on, no output: failed open, or shut down into a shorted load. Power off and measure output to ground.
  On the board:
  An output near 0 Ω to ground is usually the load. Lift the output pin to see which.
  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 pinout and whether the enable is active high or low differ between parts. 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.
  Datasheetfor AOZ1381DI-02, opens in a new tab
- AOZ2151EQI-30printed ABEMDC DC converter, Alpha & Omega SemiconductorDC DC converterNot recordedAlpha & Omega Semiconductor
  Printed ABEM. 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.
  Datasheetfor AOZ2151EQI-30, opens in a new tab
- AOZ2151EQI-31printed ABEWDC DC converter, Alpha & Omega SemiconductorDC DC converterNot recordedAlpha & Omega Semiconductor
  Printed ABEW. 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.
  Datasheetfor AOZ2151EQI-31, opens in a new tab
- AOZ2151LQI-30printed ABLMDC DC converter, Alpha & Omega SemiconductorDC DC converterNot recordedAlpha & Omega Semiconductor
  Printed ABLM. 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.
  Datasheetfor AOZ2151LQI-30, opens in a new tab
- AOZ2151PQI-05printed ABP5DC DC converter, Alpha & Omega SemiconductorDC DC converterNot recordedAlpha & Omega Semiconductor
  Printed ABP5. 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.
  Datasheetfor AOZ2151PQI-05, opens in a new tab
- AOZ2151TQI-19printed ABTLDC DC converter, Alpha & Omega SemiconductorDC DC converterNot recordedAlpha & Omega Semiconductor
  Printed ABTL. 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.
  Datasheetfor AOZ2151TQI-19, opens in a new tab
- AOZ13287DI-01printed AB01Load switch, Alpha & Omega SemiconductorLoad switchNot recordedAlpha & Omega Semiconductor
  Printed AB01. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  Load switch
  Maker
  Alpha & Omega Semiconductor
  Package
  Not recorded
  Pins
  Not recorded
  Details
  USB Type-C protection switch
  Source
  From the manufacturer's datasheet
  Is it dead?
  Voltage, board powered, black probe on ground.
  Working, it reads
  Switched on, the output pin sits at the input voltage. Switched off, it sits near 0 V.
  Dead, it reads
  Output at the input voltage while switched off: the pass element has shorted.
  Input present and switched on, no output: failed open, or shut down into a shorted load. Power off and measure output to ground.
  On the board:
  An output near 0 Ω to ground is usually the load. Lift the output pin to see which.
  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 pinout and whether the enable is active high or low differ between parts. 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.
  Datasheetfor AOZ13287DI-01, opens in a new tab
- AOZ13287DI-03printed AB03Load switch, Alpha & Omega SemiconductorLoad switchNot recordedAlpha & Omega Semiconductor
  Printed AB03. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  Load switch
  Maker
  Alpha & Omega Semiconductor
  Package
  Not recorded
  Pins
  Not recorded
  Details
  USB Type-C protection switch
  Source
  From the manufacturer's datasheet
  Is it dead?
  Voltage, board powered, black probe on ground.
  Working, it reads
  Switched on, the output pin sits at the input voltage. Switched off, it sits near 0 V.
  Dead, it reads
  Output at the input voltage while switched off: the pass element has shorted.
  Input present and switched on, no output: failed open, or shut down into a shorted load. Power off and measure output to ground.
  On the board:
  An output near 0 Ω to ground is usually the load. Lift the output pin to see which.
  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 pinout and whether the enable is active high or low differ between parts. 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.
  Datasheetfor AOZ13287DI-03, opens in a new tab
- ESDU1V5AG4Cprinted ABCESD protection diode, JSCJESD protection diodeNot recordedJSCJ
  Printed ABC. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
  What it is
  ESD protection diode
  Maker
  JSCJ
  Package
  Not recorded
  Pins
  Not recorded
  Details
  ESD protection diode, VRWM 1.5 V
  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.
  Datasheetfor ESDU1V5AG4C, opens in a new tab

One code, several parts

Marking codes are not unique. In the standard code book, 6H on a SOT-23 is an NPN transistor, a varicap, an N-channel JFET, two digital transistors, a 3.6 V voltage detector: six parts from five makers. So a search shows the parts we hold under that code and under codes easily misread as it, with only the columns that tell them apart.

6Hon a SOT-23, in the code book

NPN transistor
Varicap
N-channel JFET
Digital transistor ×2
3.6 V voltage detector

When more than one is left

Tap Help me choose. Up to 4 quick answers: whether the part has failed, then what separates the parts left. Those get ranked with the reasoning and a test that settles it. That uses one identification; 3 a month are free.

When you cannot read it

Tap the camera in the field. We read the characters, keep the ones we are unsure of, and search every reading. A photo too soft to read is turned back on your phone first; if it is the only one you can get, you can still send it.

What’s printed on it?

3 parts are printed A8

Is it dead?

Is it dead?

Is it dead?

Printed with a code easy to misread

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Codes that begin with A8

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

Is it dead?

One code, several parts

When more than one is left

When you cannot read it