SMD code T1A 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.
2 parts in SOT-23 are printed T1A
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.
PMBT3904SOT-23NPN transistor, NexperiaNPN transistorNexperia
- What it is
- NPN transistor
- Maker
- Nexperia
- Package
- SOT-23
- Pins
- 3
- Details
- Bipolar transistor, 40 V, 0.2 A
- Source
- An older or alternative marking, from a published code list
Is it dead? The meter test is below: NPN transistor.
PMMT3904SOT-23PhiNot recordedPhi
- What it is
- Not recorded
- Maker
- Phi
- Package
- SOT-23
- Pins
- 3
- Details
- 2N3904
- 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.
MBRXT1A0Schottky diode, Galaxy MicroelectronicsSchottky diodeGalaxy Microelectronics
- What it is
- Schottky diode
- Maker
- Galaxy Microelectronics
- Package
- Not recorded
- Pins
- Not recorded
- Details
- 1A, 100V, Surface Mount Schottky Barrier Rectifiers
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
SS110LHE-HFSchottky diode, ComchipSchottky diodeComchip
- What it is
- Schottky diode
- Maker
- Comchip
- Package
- Not recorded
- Pins
- Not recorded
- Details
- 100 V, 1 A Schottky barrier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky 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.
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.
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.
Schottky diode
Diode range, part lifted or one leg off the pad. Red probe on the anode.
Working, it reads
About 0.15 to 0.45 V anode to cathode, roughly half a silicon diode, and open the other way.
Dead, it reads
- The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
- A reading the wrong way round as well: leaky.
- Open both ways: failed open.
- 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 large Schottky can read about 0.1 V forward and beep like a short, and leaks a little the wrong way when good, more when warm. It is shorted only if it reads the same both ways. Measure it cold, beside an identical cold one.
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 T1A
One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.
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