Skip to content

SMD code 4Gs

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 4G was searched.

36 parts are printed 4Gs

Not sure which one you have?

Answer up to 4 quick questions and these 36 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • BC846CDWSOT-363Dual NPN transistor, 6 pins, Formosa MicrosemiDual NPN transistorSOT-3636 pinsFormosa Microsemi
    What it is
    Dual NPN transistor
    Maker
    Formosa Microsemi
    Package
    SOT-363
    Pins
    6
    Source
    Manufacturer datasheet

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

  • BC846CDW-Q1SOT-363Dual NPN transistor, 6 pins, Formosa MicrosemiDual NPN transistorSOT-3636 pinsFormosa Microsemi
    What it is
    Dual NPN transistor
    Maker
    Formosa Microsemi
    Package
    SOT-363
    Pins
    6
    Source
    Manufacturer datasheet

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

  • BC846CFSOT-23-6Transistor, 6 pins, YFWTransistorSOT-23-66 pinsYFW
    What it is
    Transistor
    Maker
    YFW
    Package
    SOT-23-6
    Pins
    6
    Details
    Bipolar transistor
    Source
    Manufacturer datasheet

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

  • BC859CSOT-23Transistor, 3 pins, DiotecTransistorSOT-233 pinsDiotec
    What it is
    Transistor
    Maker
    Diotec
    Package
    SOT-23
    Pins
    3
    Pinout
    • 1 base
    • 2 emitter
    • 3 collector
    Details
    SMD General Purpose PNP Transistors
    Source
    Manufacturer datasheet

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

  • BC860SOT-23PNP transistor, 3 pins, KECPNP transistorSOT-233 pinsKEC
    What it is
    PNP transistor
    Maker
    KEC
    Package
    SOT-23
    Pins
    3
    Details
    PNP bipolar transistor
    Source
    Manufacturer datasheet

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

  • BC860CSOT-23Transistor, 3 pins, InfineonTransistorSOT-233 pinsInfineon
    What it is
    Transistor
    Maker
    Infineon
    Package
    SOT-23
    Pins
    3
    Pinout
    • 1 base
    • 2 emitter
    • 3 collector
    Details
    SMD General Purpose PNP Transistors
    Source
    Manufacturer datasheet

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

  • BC860CWSOT-323Transistor, 3 pins, YFWTransistorSOT-3233 pinsYFW
    What it is
    Transistor
    Maker
    YFW
    Package
    SOT-323
    Pins
    3
    Details
    Bipolar transistor
    Source
    Manufacturer datasheet

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

  • BRESD4V5M1B2ZPSOD-882ESD protection diode, 2 pins, Blue RocketESD protection diodeSOD-8822 pinsBlue Rocket
    What it is
    ESD protection diode
    Maker
    Blue Rocket
    Package
    SOD-882
    Pins
    2
    Details
    ESD protection diode, bidirectional
    Source
    Manufacturer datasheet

    Is it dead? The meter test is below: TVS or ESD protection diode.

  • BZD27B91PSOD-123FZener diode, 2 pins, VishayZener diodeSOD-123F2 pinsVishay
    What it is
    Zener diode
    Maker
    Vishay
    Package
    SOD-123F
    Pins
    2
    Details
    91 V Zener diode
    Source
    Manufacturer datasheet

    Is it dead? The meter test is below: Zener diode.

  • ESD3Z18CSOD-323ESD protection diode, 2 pins, Formosa MicrosemiESD protection diodeSOD-3232 pinsFormosa Microsemi
    What it is
    ESD protection diode
    Maker
    Formosa Microsemi
    Package
    SOD-323
    Pins
    2
    Source
    Manufacturer datasheet

    Is it dead? The meter test is below: TVS or ESD protection diode.

  • JEB4V5DFPSOD-882TVS diode, 2 pins, JieJieTVS diodeSOD-8822 pinsJieJie
    What it is
    TVS diode
    Maker
    JieJie
    Package
    SOD-882
    Pins
    2
    Source
    Manufacturer datasheet

    Is it dead? The meter test is below: TVS or ESD protection diode.

  • MM5Z4684SOD-523Zener diode, 2 pins, onsemiZener diodeSOD-5232 pinsonsemi
    What it is
    Zener diode
    Maker
    onsemi
    Package
    SOD-523
    Pins
    2
    Details
    Zener Voltage Regulators MM5Z4xxxTxG Series, SZMM5Z4xxxTxG Series
    Source
    Manufacturer datasheet

    Is it dead? The meter test is below: Zener diode.

  • ADA-4789SOT-893 pins, BroadcomNot recordedSOT-893 pinsBroadcom
    What it is
    Not recorded
    Maker
    Broadcom
    Package
    SOT-89
    Pins
    3
    Source
    Published code list

    Is it dead? The meter test is below: This part.

  • 2 more parts have no package on record
    • ESD8504GMUESD protection diode, onsemiESD protection diodeNot recordedNot recordedonsemi
      What it is
      ESD protection diode
      Maker
      onsemi
      Package
      Not recorded
      Pins
      Not recorded
      Source
      Manufacturer datasheet

      Is it dead? The meter test is below: TVS or ESD protection diode.

    • AP7341-25FS4-7RLDO regulator, Diodes IncorporatedLDO regulatorNot recordedNot recordedDiodes Incorporated
      What it is
      LDO regulator
      Maker
      Diodes Incorporated
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Linear voltage regulator IC: LDO, 2.5V±1%, 300mA, +CE
      Source
      Published code list

      Is it dead? The meter test is below: Voltage regulator.

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 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.

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.

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.

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.

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.

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.

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.

Printed with a code easy to misread as 4Gs

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 53 more parts.

Did you find your part?

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