SMD code 3401
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.
3401 on a chip resistor
3.4 kΩ
3.4 kΩ resistor, 1%
340 followed by 1 zero. Four digits is normally the 1% series.
Check it with a meter
Lift one end and measure across it. A good one reads 3.4 kΩ within 1%. Measuring it in circuit reads the parallel combination of everything around it, which is almost always lower, never higher: well above 3.4 kΩ on the board is a fault. Open, or well above 3.4 kΩ, means it has failed: burnt, cracked or corroded. That does not change what to fit: the marking still says 3.4 kΩ. A burnt resistor usually means the part it feeds drew too much, so find that before fitting a new one.
On a transistor or diode body (DFN, SOT-23, SOIC-8), 3401 is a part code instead. Those parts are listed below.
21 parts are printed 3401
Not sure which one you have?
Answer up to 4 quick questions and these 21 parts are ranked, with a meter test that settles it. It works on a dead part too.
TBL3401-3LSOT-23P-channel MOSFET, 3 pins, Galaxy MicroelectronicsP-channel MOSFETSOT-233 pinsGalaxy Microelectronics
- What it is
- P-channel MOSFET
- Maker
- Galaxy Microelectronics
- Package
- SOT-23
- Pins
- 3
- Details
- 4.2A, 30V, 1.25W, P Channel, Power MOSFETs
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: P-channel MOSFET.
TBL3401DF1DFNP-channel MOSFET, Galaxy MicroelectronicsP-channel MOSFETDFNNot recordedGalaxy Microelectronics
- What it is
- P-channel MOSFET
- Maker
- Galaxy Microelectronics
- Package
- DFN
- Pins
- Not recorded
- Details
- -30V, P Channel MOSFETs
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: P-channel MOSFET.
WM03P42MSOT-233 pins, WayonNot recordedSOT-233 pinsWayon
- What it is
- Not recorded
- Maker
- Wayon
- Package
- SOT-23
- Pins
- 3
- Details
- MOSFET
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: MOSFET.
WM03P42M2SOT-233 pins, WayonNot recordedSOT-233 pinsWayon
- What it is
- Not recorded
- Maker
- Wayon
- Package
- SOT-23
- Pins
- 3
- Details
- MOSFET
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: MOSFET.
MTP3401N3SOT-23P-channel MOSFET, 3 pins, CYStekP-channel MOSFETSOT-233 pinsCYStek
- What it is
- P-channel MOSFET
- Maker
- CYStek
- Package
- SOT-23
- Pins
- 3
- Details
- -30 V, -3.5 A P-channel MOSFET
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: P-channel MOSFET.
LT1034CS8-1.2SOIC-88 pins, Analog DevicesNot recordedSOIC-88 pinsAnalog Devices
- What it is
- Not recorded
- Maker
- Analog Devices
- Package
- SOIC-8
- Pins
- 8
- Details
- equivalent LT1034CZ-1.2
- Source
- Published code list
Is it dead? The meter test is below: This part.
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.
P-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 drain, black on the source: 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. 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.
MOSFET
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
- 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.
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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