SMD code 1As
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 1A was searched.
140 parts are printed 1As
Not sure which one you have?
Answer up to 4 quick questions and these 50 parts are ranked, with a meter test that settles it. It works on a dead part too.
LM5Z47VT1GSOD-523Zener diode, 2 pins, LRCZener diodeSOD-5232 pinsLRC
- What it is
- Zener diode
- Maker
- LRC
- Package
- SOD-523
- Pins
- 2
- Details
- Zener diode, VZ Min 44 V, VZ Nom 47 V, VZ Max 50 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
LMBT3904N3T5GSOT-883NPN transistor, 3 pins, LRCNPN transistorSOT-8833 pinsLRC
- What it is
- NPN transistor
- Maker
- LRC
- Package
- SOT-883
- Pins
- 3
- Details
- Bipolar transistor, NPN, IC 200 mA, VCEO 40 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
MM3Z47VSOD-323Zener diode, 2 pins, LeiditechZener diodeSOD-3232 pinsLeiditech
- What it is
- Zener diode
- Maker
- Leiditech
- Package
- SOD-323
- Pins
- 2
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
MM5Z47SOD-523Zener diode, 2 pins, LeiditechZener diodeSOD-5232 pinsLeiditech
- What it is
- Zener diode
- Maker
- Leiditech
- Package
- SOD-523
- Pins
- 2
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
MM5Z47VSOD-523Zener diode, 2 pins, onsemiZener diodeSOD-5232 pinsonsemi
- What it is
- Zener diode
- Maker
- onsemi
- Package
- SOD-523
- Pins
- 2
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
MMBT3904SOT-23NPN transistor, 3 pins, InfineonNPN transistorSOT-233 pinsInfineon
- What it is
- NPN transistor
- Maker
- Infineon
- Package
- SOT-23
- Pins
- 3
- Details
- NPN bipolar transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
MMBT3904W-CSOT-323Transistor, 3 pins, SeCoSTransistorSOT-3233 pinsSeCoS
- What it is
- Transistor
- Maker
- SeCoS
- Package
- SOT-323
- Pins
- 3
- Details
- Bipolar transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Bipolar transistor.
PJSOT03SOT-23ESD protection diode, 3 pins, PanjitESD protection diodeSOT-233 pinsPanjit
- What it is
- ESD protection diode
- Maker
- Panjit
- Package
- SOT-23
- Pins
- 3
- Details
- 3V, 500W, Surface Mount TVS
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
PMBT3904SOT-23NPN transistor, 3 pins, NexperiaNPN transistorSOT-233 pinsNexperia
- What it is
- NPN transistor
- Maker
- Nexperia
- Package
- SOT-23
- Pins
- 3
- Pinout
- 1 base
- 2 emitter
- 3 collector
- Details
- Bipolar transistor, 40 V, 0.2 A
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
PMST3904SOT-323NPN transistor, 3 pins, NexperiaNPN transistorSOT-3233 pinsNexperia
- What it is
- NPN transistor
- Maker
- Nexperia
- Package
- SOT-323
- Pins
- 3
- Details
- Bipolar transistor, 40 V, 0.2 A
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
PS2405-D63SOT-883ESD protection diode, 3 pins, PanjitESD protection diodeSOT-8833 pinsPanjit
- What it is
- ESD protection diode
- Maker
- Panjit
- Package
- SOT-883
- Pins
- 3
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
PSGP1ASOD-323Rectifier, 2 pins, PrisemiRectifierSOD-3232 pinsPrisemi
- What it is
- Rectifier
- Maker
- Prisemi
- Package
- SOD-323
- Pins
- 2
- Details
- Rectifier diode, 1 A, 50 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Silicon diode.
PXT3904SOT-89NPN transistor, 3 pins, Galaxy MicroelectronicsNPN transistorSOT-893 pinsGalaxy Microelectronics
- What it is
- NPN transistor
- Maker
- Galaxy Microelectronics
- Package
- SOT-89
- Pins
- 3
- Details
- 40V, 0.2A, General Purpose NPN Bipolar Transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
PXT3904-TPSOT-89NPN transistor, 3 pins, HXYNPN transistorSOT-893 pinsHXY
- What it is
- NPN transistor
- Maker
- HXY
- Package
- SOT-89
- Pins
- 3
- Details
- Bipolar transistor, 40 V, 0.2 A
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: NPN transistor.
1 more part has no package on record
MM5Z47V-Q1Zener diode, Formosa MicrosemiZener diodeNot recordedNot recordedFormosa Microsemi
- What it is
- Zener diode
- Maker
- Formosa Microsemi
- Package
- Not recorded
- Pins
- Not recorded
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener 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.
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.
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.
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.
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.
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.
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