SMD code -1D in SOT-23
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.
29 parts in SOT-23 are printed -1D
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.
all SOT-23, 3 pins. What differs:
BC846SOT-23NPN transistor, NexperiaNPN transistorNexperia
- What it is
- NPN transistor
- Maker
- Nexperia
- Package
- SOT-23
- Pins
- 3
- Pinout
- 1 base
- 2 emitter
- 3 collector
- Details
- NPN bipolar transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
BC846ASOT-23NPN transistor, Taitron ComponentsNPN transistorTaitron Components
- What it is
- NPN transistor
- Maker
- Taitron Components
- Package
- SOT-23
- Pins
- 3
- Details
- 65 V NPN small-signal transistor, gain group A
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
BC846BSOT-23NPN transistor, Taitron ComponentsNPN transistorTaitron Components
- What it is
- NPN transistor
- Maker
- Taitron Components
- Package
- SOT-23
- Pins
- 3
- Details
- 65 V NPN small-signal transistor, gain group B
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
EMB32N03JSOT-23N-channel MOSFET, Excelliance MOSN-channel MOSFETExcelliance MOS
- What it is
- N-channel MOSFET
- Maker
- Excelliance MOS
- Package
- SOT-23
- Pins
- 3
- Details
- 30 V, 5 A N-channel MOSFET
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: N-channel MOSFET.
EMB32N03JSSOT-23N-channel MOSFET, Excelliance MOSN-channel MOSFETExcelliance MOS
- What it is
- N-channel MOSFET
- Maker
- Excelliance MOS
- Package
- SOT-23
- Pins
- 3
- Details
- 30 V, 5 A N-channel MOSFET
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: N-channel MOSFET.
FMBTA42SOT-23NPN transistor, Formosa MicrosemiNPN transistorFormosa Microsemi
- What it is
- NPN transistor
- Maker
- Formosa Microsemi
- Package
- SOT-23
- Pins
- 3
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
FMBTA42-Q1SOT-23NPN transistor, Formosa MicrosemiNPN transistorFormosa Microsemi
- What it is
- NPN transistor
- Maker
- Formosa Microsemi
- Package
- SOT-23
- Pins
- 3
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
LMBTA42LT1GSOT-23NPN transistor, LRCNPN transistorLRC
- What it is
- NPN transistor
- Maker
- LRC
- Package
- SOT-23
- Pins
- 3
- Details
- Bipolar transistor, NPN, IC 50 mA, VCEO 300 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
MMBTA42SOT-23NPN transistor, InfineonNPN transistorInfineon
- What it is
- NPN transistor
- Maker
- Infineon
- Package
- SOT-23
- Pins
- 3
- Details
- NPN bipolar transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
MMBTA42-HFSOT-23NPN transistor, ComchipNPN transistorComchip
- What it is
- NPN transistor
- Maker
- Comchip
- Package
- SOT-23
- Pins
- 3
- Details
- 300 V, 0.5 A NPN transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
MMBTA42-LSOT-23Transistor, YFWTransistorYFW
- What it is
- Transistor
- Maker
- YFW
- Package
- SOT-23
- Pins
- 3
- Details
- Bipolar transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Bipolar transistor.
MMBTA42LSOT-23NPN transistor, onsemiNPN transistoronsemi
- What it is
- NPN transistor
- Maker
- onsemi
- Package
- SOT-23
- Pins
- 3
- Details
- High Voltage Transistors
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
MMBTA42QSOT-23NPN transistor, Yangjie Electronic TechNPN transistorYangjie Electronic Tech
- What it is
- NPN transistor
- Maker
- Yangjie Electronic Tech
- Package
- SOT-23
- Pins
- 3
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
MMBTA42YSOT-23Transistor, SeCoSTransistorSeCoS
- What it is
- Transistor
- Maker
- SeCoS
- Package
- SOT-23
- Pins
- 3
- Details
- Bipolar transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Bipolar transistor.
PMBTA42SOT-23NPN transistor, NexperiaNPN transistorNexperia
- What it is
- NPN transistor
- Maker
- Nexperia
- Package
- SOT-23
- Pins
- 3
- Pinout
- 1 base
- 2 emitter
- 3 collector
- Details
- 300 V, 100 mA NPN high-voltage transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN 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.
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.
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.
Bipolar transistor
Diode range, part lifted or its base leg off the pad.
Working, it reads
From the base, one probe colour reads about 0.6 to 0.75 V to the emitter and to the collector, and open the other way round. Collector to emitter reads open both ways.
Dead, it reads
- Collector to emitter the same both ways, near 0 V with a continuous beep: shorted. The commonest failure.
- The base the same both ways to another pin, near 0 V or a middling value: a shorted junction.
- Only one junction reads, or none: a junction has failed open. It then looks like a diode.
- A reading the wrong way round, where it should be open: leaky.
- On the board
- this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
- Compare:
- If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
- Watch for:
- A pair of diodes with a common pin reads just like a transistor, and some transistors carry a built-in diode or resistor. The datasheet says which.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Printed with a code easy to misread as -1D
One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.
Codes not listed here are printed on 9 more parts.
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