SMD code AJs
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.
The last letter, s, is lower case, which on NXP and Philips parts is a date or factory code, so it was set aside and AJ was searched.
136 parts are printed AJs
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.
SMAJ15CA-TRSMATVS diode, 2 pins, STMicroelectronicsTVS diodeSMA2 pinsSTMicroelectronics
- What it is
- TVS diode
- Maker
- STMicroelectronics
- Package
- SMA
- Pins
- 2
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
T2SD1782-QSOT-23NPN transistor, 3 pins, Galaxy MicroelectronicsNPN transistorSOT-233 pinsGalaxy Microelectronics
- What it is
- NPN transistor
- Maker
- Galaxy Microelectronics
- Package
- SOT-23
- Pins
- 3
- Details
- 80V, 0.5A, General Purpose NPN Bipolar Transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
T2SD1782-RSOT-23NPN transistor, 3 pins, Galaxy MicroelectronicsNPN transistorSOT-233 pinsGalaxy Microelectronics
- What it is
- NPN transistor
- Maker
- Galaxy Microelectronics
- Package
- SOT-23
- Pins
- 3
- Details
- 80V, 0.5A, General Purpose NPN Bipolar Transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
TBCX70JSOT-23NPN transistor, 3 pins, Galaxy MicroelectronicsNPN transistorSOT-233 pinsGalaxy Microelectronics
- What it is
- NPN transistor
- Maker
- Galaxy Microelectronics
- Package
- SOT-23
- Pins
- 3
- Details
- 45V, 0.1A, General Purpose NPN Bipolar Transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
TLV75525PDQNX2SONLDO regulator, 4 pins, Texas InstrumentsLDO regulatorX2SON4 pinsTexas Instruments
- What it is
- LDO regulator
- Maker
- Texas Instruments
- Package
- X2SON
- Pins
- 4
- Details
- 500mA, Low-IQ, Small-Size, Low-Dropout Regulator
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Voltage regulator.
BCP56L3SOT-223NPN transistor, 4 pins, CYStekNPN transistorSOT-2234 pinsCYStek
- What it is
- NPN transistor
- Maker
- CYStek
- Package
- SOT-223
- Pins
- 4
- Details
- 80 V, 1 A NPN transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
BTA1727L3SOT-223PNP transistor, 4 pins, CYStekPNP transistorSOT-2234 pinsCYStek
- What it is
- PNP transistor
- Maker
- CYStek
- Package
- SOT-223
- Pins
- 4
- Details
- -400 V, -0.3 A PNP transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: PNP transistor.
BTD1768S3SOT-323NPN transistor, 3 pins, CYStekNPN transistorSOT-3233 pinsCYStek
- What it is
- NPN transistor
- Maker
- CYStek
- Package
- SOT-323
- Pins
- 3
- Details
- 80 V, 1 A NPN transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
BTD5213L3SOT-223NPN transistor, 4 pins, CYStekNPN transistorSOT-2234 pinsCYStek
- What it is
- NPN transistor
- Maker
- CYStek
- Package
- SOT-223
- Pins
- 4
- Details
- 100 V, 1 A NPN transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
6 more parts have no package on record
PZS513V9BCHZener diode, PanjitZener diodeNot recordedNot recordedPanjit
- What it is
- Zener diode
- Maker
- Panjit
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
PZS513V9BCH-AUZener diode, PanjitZener diodeNot recordedNot recordedPanjit
- What it is
- Zener diode
- Maker
- Panjit
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
RF7G120BKFRAN-channel MOSFET, ROHMN-channel MOSFETNot recordedNot recordedROHM
- What it is
- N-channel MOSFET
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Nch 40V 12A Power MOSFET
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: N-channel MOSFET.
SDL12ESD protection diode, SeCoSESD protection diodeNot recordedNot recordedSeCoS
- What it is
- ESD protection diode
- Maker
- SeCoS
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
2SA1724Sanyo ElectricNot recordedNot recordedNot recordedSanyo Electric
- What it is
- Not recorded
- Maker
- Sanyo Electric
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Si-pnp: Vid, Hi-def, 30V, 300mA, 500mW, B=155..100, 1.5GHz
- Source
- Published code list
Is it dead? The meter test is below: This part.
2SA1812PNP transistor, ROHMPNP transistorNot recordedNot recordedROHM
- What it is
- PNP transistor
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Published code list
Is it dead? The meter test is below: PNP transistor.
Is it dead? One meter test per kind
Parts of the same kind are tested the same way, so each test is here once. Each part above points to its own.
Zener diode
Diode range for the forward check, part lifted, red probe on the anode. A bench supply for the Zener voltage.
Working, it reads
About 0.6 to 0.8 V forward and open in reverse on the diode range. Its Zener voltage shows only on a supply: feed it through a resistor that sets about 5 mA, cathode to positive, read quickly, and it should hold near its rated voltage.
Dead, it reads
- The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
- Open both ways, forward too: failed open.
- Holds well off its rated voltage on the supply test: drifted.
- A soft knee, or a voltage that creeps on the supply test: leaky.
- On the board
- this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
- Compare:
- If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
- Watch for:
- A meter's diode range stops at about 2 to 3 V, so almost every Zener reads open in reverse on it, good or bad; a 3 V meter may just show a 2.4 or 2.7 V part. Above about 3 V the meter cannot tell a Zener from a plain diode.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
N-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 source, black on the drain: 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. A drain short can be the load. 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.
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.
NPN transistor
Diode range, part lifted or its base leg off the pad.
Working, it reads
Red probe on the base reads about 0.6 to 0.75 V to the emitter and to the collector, and open the other way round. Collector to emitter reads open both ways.
Dead, it reads
- Collector to emitter the same both ways, near 0 V with a continuous beep: shorted. The commonest failure.
- The base the same both ways to another pin, near 0 V or a middling value: a shorted junction.
- Only one junction reads, or none: a junction has failed open. It then looks like a diode.
- A reading the wrong way round, where it should be open: leaky.
- On the board
- this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
- Compare:
- If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
- Watch for:
- A pair of diodes with a common pin reads just like a transistor, and some transistors carry a built-in diode or resistor. The datasheet says which.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Voltage regulator
Voltage, board powered, black probe on ground. Then ohms with the power off.
Working, it reads
Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.
Dead, it reads
- Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
- Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
- Power off, input to output near 0 Ω: shorted.
- On the board:
- An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
- Compare:
- The same regulator on another rail or another board shows the right voltages and the right resistances.
- Watch for:
- Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
PNP transistor
Diode range, part lifted or its base leg off the pad.
Working, it reads
Black probe on the base reads about 0.6 to 0.75 V to the emitter and to the collector, and open the other way round. Collector to emitter reads open both ways.
Dead, it reads
- Collector to emitter the same both ways, near 0 V with a continuous beep: shorted. The commonest failure.
- The base the same both ways to another pin, near 0 V or a middling value: a shorted junction.
- Only one junction reads, or none: a junction has failed open. It then looks like a diode.
- A reading the wrong way round, where it should be open: leaky.
- On the board
- this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
- Compare:
- If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
- Watch for:
- A pair of diodes with a common pin reads just like a transistor, and some transistors carry a built-in diode or resistor. The datasheet says which.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
This part
Diode range and ohms range, part lifted.
Working, it reads
Depends on what it is. The datasheet, or an identical part, says.
Dead, it reads
- Between two pins, the same reading both ways, near 0 V with a continuous beep: shorted.
- Open between every pair of pins: failed open, or a part that reads open when working.
- On the board
- this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
- Compare:
- If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
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