SMD code B4 in SMB
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.
3 parts in SMB are printed B4
Not sure which one you have?
Answer up to 4 quick questions and these 44 parts are ranked, with a meter test that settles it. It works on a dead part too.
FSS25SMB2 pins, FagNot recorded2 pinsFag
- What it is
- Not recorded
- Maker
- Fag
- Package
- SMB
- Pins
- 2
- Details
- Si-diode: Schottky Barrier Rectifier, 50V, 2A, Vf<0,7V(2A)
- Source
- Published code list
Is it dead? The meter test is below: Schottky diode.
SMBYT01SMB2 pins, STMicroelectronicsNot recorded2 pinsSTMicroelectronics
- What it is
- Not recorded
- Maker
- STMicroelectronics
- Package
- SMB
- Pins
- 2
- Source
- Published code list
Is it dead? The meter test is below: This part.
SMBYT01-400SMB2 pins, SGS-Thomson MicroelectronicsNot recorded2 pinsSGS-Thomson Microelectronics
- What it is
- Not recorded
- Maker
- SGS-Thomson Microelectronics
- Package
- SMB
- Pins
- 2
- Details
- Si-diode: Rectifier, Fast Recovery, 400V, 1A, Vf<1,05V(1A), <25ns
- Source
- Published code list
Is it dead? The meter test is below: Silicon diode.
12 more parts have no package on record. Nothing rules them out, so they stay.
ACDBUC0145-HFSchottky diode, ComchipSchottky diodeNot recordedComchip
- What it is
- Schottky diode
- Maker
- Comchip
- Package
- Not recorded
- Pins
- Not recorded
- Details
- 50 V, 0.1 A Schottky barrier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
CDBU0145-HFSchottky diode, ComchipSchottky diodeNot recordedComchip
- What it is
- Schottky diode
- Maker
- Comchip
- Package
- Not recorded
- Pins
- Not recorded
- Details
- 50 V, 0.1 A Schottky barrier diode
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
GSEZ5B302ESD protection diode, Good-ArkESD protection diodeNot recordedGood-Ark
- What it is
- ESD protection diode
- Maker
- Good-Ark
- Package
- Not recorded
- Pins
- Not recorded
- Details
- ESD protection diode, VRWM 5 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
LFCN-2750+RF filter, Mini-CircuitsRF filterNot recordedMini-Circuits
- What it is
- RF filter
- Maker
- Mini-Circuits
- Package
- Not recorded
- Pins
- Not recorded
- Details
- LTCC filter
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: This part.
NC7SZ19FHAnalog switch, onsemiAnalog switchNot recordedonsemi
- What it is
- Analog switch
- Maker
- onsemi
- Package
- Not recorded
- Pins
- Not recorded
- Details
- TinyLogic UHS 1-of-2 Decoder / Demultiplexer
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Integrated circuit.
NC7SZ19L6Analog switch, onsemiAnalog switchNot recordedonsemi
- What it is
- Analog switch
- Maker
- onsemi
- Package
- Not recorded
- Pins
- Not recorded
- Details
- TinyLogic UHS 1-of-2 Decoder / Demultiplexer
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Integrated circuit.
TSCD054WSchottky diode, Taitron ComponentsSchottky diodeNot recordedTaitron Components
- What it is
- Schottky diode
- Maker
- Taitron Components
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Low Profile Chip Type Schottky Rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
TSCD054WSSchottky diode, Taitron ComponentsSchottky diodeNot recordedTaitron Components
- What it is
- Schottky diode
- Maker
- Taitron Components
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Low Profile Chip Type Schottky Rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
TSCD0540Schottky diode, Taitron ComponentsSchottky diodeNot recordedTaitron Components
- What it is
- Schottky diode
- Maker
- Taitron Components
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Low Profile Chip Type Schottky Rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
TSD054WSchottky diode, Taitron ComponentsSchottky diodeNot recordedTaitron Components
- What it is
- Schottky diode
- Maker
- Taitron Components
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Schottky Barrier Diodes (Two Terminals)
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
2SC16213 pins, RenesasNot recorded3 pinsRenesas
- What it is
- Not recorded
- Maker
- Renesas
- Package
- Not recorded
- Pins
- 3
- Details
- NPN High Speed Switch 20v 200mA
- Source
- Published code list
Is it dead? The meter test is below: This part.
2SC4987-4Sanyo ElectricNot recordedNot recordedSanyo Electric
- What it is
- Not recorded
- Maker
- Sanyo Electric
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Si-npn: Sw, Hi-Sp, 40V, 200mA, 150mW, B=50..100, 750MHz
- 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.
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.
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.
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.
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.
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 B4
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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