SMD code J12 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.
4 parts in SOT-23 are printed J12
Not sure which one you have?
Answer up to 4 quick questions and these 6 parts are ranked, with a meter test that settles it. It works on a dead part too.
CHT856BGPSOT-23PNP transistor, 3 pins, ChenmkoPNP transistor3 pinsChenmko
- What it is
- PNP transistor
- Maker
- Chenmko
- Package
- SOT-23
- Pins
- 3
- Details
- PNP Muti-Chip General Purpose Amplifier, 65 V, 0.1 A
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: PNP transistor.
PJSOT12SOT-23ESD protection diode, 3 pins, Galaxy MicroelectronicsESD protection diode3 pinsGalaxy Microelectronics
- What it is
- ESD protection diode
- Maker
- Galaxy Microelectronics
- Package
- SOT-23
- Pins
- 3
- Details
- 12V, 500W, Surface Mount TVS
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
CHT856BPT-SSOT-23PNP transistor, 3 pins, Chenmko EnterprisePNP transistor3 pinsChenmko Enterprise
- What it is
- PNP transistor
- Maker
- Chenmko Enterprise
- Package
- SOT-23
- Pins
- 3
- Details
- PNP transistor: AF, Sw, 65V, 100mA, B=420..800, 200MHz
- Source
- Published code list
Is it dead? The meter test is below: PNP transistor.
SO2906ARSOT-233 pinsNot recorded3 pinsNot recorded
- What it is
- Not recorded
- Maker
- Not recorded
- Package
- SOT-23
- Pins
- 3
- Details
- equivalent 2N2906A
- Source
- Published code list
Is it dead? The meter test is below: This part.
2 more parts have no package on record. Nothing rules them out, so they stay.
QH8J12P-channel MOSFET, ROHMP-channel MOSFETNot recordedROHM
- What it is
- P-channel MOSFET
- Maker
- ROHM
- Package
- Not recorded
- Pins
- Not recorded
- Details
- -12V Dual P-channel Power MOSFET
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: P-channel MOSFET.
TE2906A3 pins, Compagnie générale de télégraphie Sans Fil (Thomson-CSF)Not recorded3 pinsCompagnie générale de télégraphie Sans Fil (Thomson-CSF)
- What it is
- Not recorded
- Maker
- Compagnie générale de télégraphie Sans Fil (Thomson-CSF)
- Package
- Not recorded
- Pins
- 3
- Details
- equivalent 2N2906A
- 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.
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.
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.
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.
Printed with a code easy to misread as J12
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 J12
For a marking with its end worn or burnt off. Each code has a page of its own.
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