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SMD code 1L

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.

4 parts are printed 1L

Not sure which one you have?

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

  • BC848CSOT-23NPN transistor, 3 pins, Infineon
    What it is
    NPN transistor
    Maker
    Infineon
    Package
    SOT-23
    Pins
    3
    Details
    30 V NPN small-signal transistor, gain group C
    Source
    From the manufacturer's datasheet

    Is it dead? The meter test is below: NPN transistor.

    Datasheetfor BC848C, opens in a new tab
  • BC848CWSOT-323Transistor, 3 pins, Diotec
    What it is
    Transistor
    Maker
    Diotec
    Package
    SOT-323
    Pins
    3
    Details
    SMD General Purpose NPN Transistors
    Source
    From the manufacturer's datasheet

    Is it dead? The meter test is below: Bipolar transistor.

    Datasheetfor BC848CW, opens in a new tab
  • BCV61CSOT-143Dual NPN transistor, 4 pins, Infineon
    What it is
    Dual NPN transistor
    Maker
    Infineon
    Package
    SOT-143
    Pins
    4
    Details
    30 V, 100 mA NPN current-mirror double transistor
    Source
    From the manufacturer's datasheet

    Is it dead? The meter test is below: NPN transistor pair.

    Datasheetfor BCV61C, opens in a new tab
  • PMBT6429SOT-23NPN transistor, 3 pins, Nexperia
    What it is
    NPN transistor
    Maker
    Nexperia
    Package
    SOT-23
    Pins
    3
    Pinout
    • 1 base
    • 2 emitter
    • 3 collector
    Details
    45 V, 100 mA NPN general-purpose (high-gain) transistor
    Source
    From the manufacturer's datasheet

    Is it dead? The meter test is below: NPN transistor.

    Datasheetfor PMBT6429, opens in a new tab

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.

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.

NPN transistor pair

Diode range, part lifted. Test each transistor on its own pins, as the datasheet's pinout gives them.

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.

Printed with a code easy to misread as 1L

One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.

Codes that begin with 1L

For a marking with its end worn or burnt off. Each code has a page of its own.

Codes not listed here are printed on 28 more parts.

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