SMD code U12
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.
U12 on a chip capacitor
120 nF
120 nF capacitor
The u is both the decimal point and the unit: 120 nF.
Check it with a meter
Lift one end and measure it on a capacitance range. A good one reads close to 120 nF. In circuit the meter also sees everything connected across it, so the reading means little until it is out. A failed one usually reads near 0 Ω, or a steady low resistance, on the ohms range, often from a crack. On the board a shorted capacitor shorts its whole rail. A failed reading does not change what to fit: the marking still says 120 nF.
On a transistor or diode body (SOT-23-5, SOT-23, SOT-89-5), U12 is a part code instead. Those parts are listed below.
8 parts are printed U12
Not sure which one you have?
Answer up to 4 quick questions and these 8 parts are ranked, with a meter test that settles it. It works on a dead part too.
2SC2758-12SOT-23RF transistor, 3 pins, NEC ElectronicsRF transistorSOT-233 pinsNEC Electronics
- What it is
- RF transistor
- Maker
- NEC Electronics
- Package
- SOT-23
- Pins
- 3
- Details
- NPN transistor: RF-amp, 25V, 20mA, 150mW, B=60..120, 750MHz
- Source
- Published code list
Is it dead? The meter test is below: Bipolar transistor.
2SC2758U12SOT-233 pinsNot recordedSOT-233 pinsNot recorded
- What it is
- Not recorded
- Maker
- Not recorded
- Package
- SOT-23
- Pins
- 3
- Source
- Published code list
Is it dead? The meter test is below: This part.
XC9226A126MSOT-23-5DC-DC converter, 5 pins, TorexDC-DC converterSOT-23-55 pinsTorex
- What it is
- DC-DC converter
- Maker
- Torex
- Package
- SOT-23-5
- Pins
- 5
- Details
- DC/DC voltage converter IC: PWM/PFM st-dwn, 600kHz, 1.2V±1%, 600mA, +CE
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
XC9226B126MSOT-23-5DC-DC converter, 5 pins, TorexDC-DC converterSOT-23-55 pinsTorex
- What it is
- DC-DC converter
- Maker
- Torex
- Package
- SOT-23-5
- Pins
- 5
- Details
- DC/DC voltage converter IC: PWM/PFM st-dwn, 600kHz, 1.2V±1%, 600mA, -CE
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
XC9226C126MSOT-23-5DC-DC converter, 5 pins, TorexDC-DC converterSOT-23-55 pinsTorex
- What it is
- DC-DC converter
- Maker
- Torex
- Package
- SOT-23-5
- Pins
- 5
- Details
- DC/DC voltage converter IC: PWM/PFM st-dwn, 600kHz, 1.2V±1%, 600mA, +CE, PDR
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
XC9226D126MSOT-23-5DC-DC converter, 5 pins, TorexDC-DC converterSOT-23-55 pinsTorex
- What it is
- DC-DC converter
- Maker
- Torex
- Package
- SOT-23-5
- Pins
- 5
- Details
- DC/DC voltage converter IC: PWM/PFM st-dwn, 600kHz, 1.2V±1%, 600mA, -CE, PUR
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
2 more parts have no package on record
QS5U12N-channel MOSFET, ROHMN-channel MOSFETNot recordedNot recordedROHM
- What it is
- N-channel MOSFET
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- N-Channel MOSFET + Schottky Barrier Diode
- Source
- Published code list
Is it dead? The meter test is below: N-channel MOSFET.
USM12SPTRectifier, Chenmko EnterpriseRectifierNot recordedNot recordedChenmko Enterprise
- What it is
- Rectifier
- Maker
- Chenmko Enterprise
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Diode: Rectifier, S-fast, 100V, 1A
- Source
- Published code list
Is it dead? The meter test is below: Silicon diode.
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.
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.
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.
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.
Silicon diode
Diode range, part lifted or one leg off the pad. Red probe on the anode.
Working, it reads
About 0.5 to 0.8 V anode to cathode, and open the other way. Small switching diodes read about 0.6 to 0.7 V; large rectifiers can read a little lower.
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: failed open.
- A reading the wrong way round as well: 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 three-pin body can hold two diodes. With a common pin they read two junctions from that pin, just like a transistor; in series they read two drops end to end. Test each pair the datasheet names.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Integrated circuit
Voltage with the board powered; ohms from each pin to ground with it off.
Working, it reads
Supply pin at its voltage and the output doing what the datasheet says. Readings between pins depend on the part.
Dead, it reads
- A pin near 0 Ω to ground or to the supply pin where an identical part does not read that: failed short.
- Supply present, output stuck: failed, or its load has.
- On the board:
- A pin shorted to ground on the board can be anything on that net. Lift the pin to be sure.
- Compare:
- The surest reference is the same IC on a working board, measured pin by pin.
- Watch for:
- Its protection diodes can read like junctions between pins, even like a transistor. That proves nothing either way.
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 U12
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 U12
For a marking with its end worn or burnt off. Each code has a page of its own.
Did you find your part?
Open this in the search to correct a character or try another package.