SMD code search: identify a part by its marking
4 parts are printed BJB. 3 printed with a similar-looking code.
4 parts are printed BJB
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.
MPS8550SSOT-23Transistor, 3 pins, KECTransistorSOT-233 pinsKEC
- What it is
- Transistor
- Maker
- KEC
- Package
- SOT-23
- Pins
- 3
- Source
- Manufacturer datasheet
Is it dead?
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.
S-8520E16MC-BJBT2SOT-23-55 pins, ABLICNot recordedSOT-23-55 pinsABLIC
- What it is
- Not recorded
- Maker
- ABLIC
- Package
- SOT-23-5
- Pins
- 5
- Source
- Published code list
Is it dead?
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.
TC1302BJBVMFDFNLDO regulator, MicrochipLDO regulatorDFNNot recordedMicrochip
- What it is
- LDO regulator
- Maker
- Microchip
- Package
- DFN
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, Dual out, Vo1/Vo2=2.4V(300mA)/3.2V(150mA)±2.5%, +CE
- Source
- Published code list
Is it dead?
Voltage, board powered, black probe on ground. Then ohms with the power off.
Working, it reads
Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.
Dead, it reads
- Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
- Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
- Power off, input to output near 0 Ω: shorted.
- On the board:
- An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
- Compare:
- The same regulator on another rail or another board shows the right voltages and the right resistances.
- Watch for:
- Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
UM1750DA-31DFNLDO regulator, Union SemiconductorLDO regulatorDFNNot recordedUnion Semiconductor
- What it is
- LDO regulator
- Maker
- Union Semiconductor
- Package
- DFN
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, 3.1V±2%, 350mA, +CE
- Source
- Published code list
Is it dead?
Voltage, board powered, black probe on ground. Then ohms with the power off.
Working, it reads
Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.
Dead, it reads
- Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
- Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
- Power off, input to output near 0 Ω: shorted.
- On the board:
- An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
- Compare:
- The same regulator on another rail or another board shows the right voltages and the right resistances.
- Watch for:
- Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
3 more parts are printed with a code easy to misread as BJB
Printed with a code easy to misread
One character differs, and it is one that is easy to confuse under a lamp. The odd one out is marked on each.
MMBZ5263ELprinted BJ8SOT-23Zener diode, 3 pins, onsemiZener diodeSOT-233 pinsonsemi
Printed BJ8 on the part. Easy to misread as BJB. Check that character with a loupe before you order anything.
- What it is
- Zener diode
- Maker
- onsemi
- Package
- SOT-23
- Pins
- 3
- Details
- Zener Voltage Regulators MMBZ52xxELT1G Series, SZMMBZ52xxELT1G Series
- Source
- Manufacturer datasheet
Is it dead?
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.
MMBZ5263Eprinted BJ8SOT-23Zener diode, 3 pins, onsemiZener diodeSOT-233 pinsonsemi
Printed BJ8 on the part. Easy to misread as BJB. Check that character with a loupe before you order anything.
- What it is
- Zener diode
- Maker
- onsemi
- Package
- SOT-23
- Pins
- 3
- Details
- Zener diode: 56V±5%, Izt=2.2mA, Zzt=150, 225mW
- Source
- Published code list
Is it dead?
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.
UM1750DA-28printed BJ8DFNLDO regulator, Union SemiconductorLDO regulatorDFNNot recordedUnion Semiconductor
Printed BJ8 on the part. Easy to misread as BJB. Check that character with a loupe before you order anything.
- What it is
- LDO regulator
- Maker
- Union Semiconductor
- Package
- DFN
- Pins
- Not recorded
- Details
- Linear voltage regulator IC: LDO, 2.8V±2%, 350mA, +CE
- Source
- Published code list
Is it dead?
Voltage, board powered, black probe on ground. Then ohms with the power off.
Working, it reads
Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.
Dead, it reads
- Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
- Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
- Power off, input to output near 0 Ω: shorted.
- On the board:
- An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
- Compare:
- The same regulator on another rail or another board shows the right voltages and the right resistances.
- Watch for:
- Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
10 more parts have codes that begin with BJB
Codes that begin with BJB
For a marking with its end worn or burnt off. Each one shows its full printed code.
TC1301BJBAVMFprinted BJBADFNMicrochipNot recordedDFNNot recordedMicrochip
Printed BJBA. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
- What it is
- Not recorded
- Maker
- Microchip
- Package
- DFN
- Pins
- Not recorded
- Details
- Linear voltage regulator with volatge detector: LDO, Dual out, Vo1/Vo2=2.4V(300mA)/3.2V(150mA)±2.5%, Vdet=2.63V±2.5%, +…
- Source
- Published code list
Is it dead?
Voltage, board powered, black probe on ground. Then ohms with the power off.
Working, it reads
Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.
Dead, it reads
- Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
- Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
- Power off, input to output near 0 Ω: shorted.
- On the board:
- An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
- Compare:
- The same regulator on another rail or another board shows the right voltages and the right resistances.
- Watch for:
- Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
TC1301BJBBVMFprinted BJBBDFNMicrochipNot recordedDFNNot recordedMicrochip
Printed BJBB. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
- What it is
- Not recorded
- Maker
- Microchip
- Package
- DFN
- Pins
- Not recorded
- Details
- Linear voltage regulator with volatge detector: LDO, Dual out, Vo1/Vo2=2.4V(300mA)/3.2V(150mA)±2.5%, Vdet=2.2V±2.5%, +CE
- Source
- Published code list
Is it dead?
Voltage, board powered, black probe on ground. Then ohms with the power off.
Working, it reads
Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.
Dead, it reads
- Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
- Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
- Power off, input to output near 0 Ω: shorted.
- On the board:
- An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
- Compare:
- The same regulator on another rail or another board shows the right voltages and the right resistances.
- Watch for:
- Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
TC1301BJBCVMFprinted BJBCDFNMicrochipNot recordedDFNNot recordedMicrochip
Printed BJBC. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
- What it is
- Not recorded
- Maker
- Microchip
- Package
- DFN
- Pins
- Not recorded
- Details
- Linear voltage regulator with volatge detector: LDO, Dual out, Vo1/Vo2=2.4V(300mA)/3.2V(150mA)±2.5%, Vdet=2.32V±2.5%, +…
- Source
- Published code list
Is it dead?
Voltage, board powered, black probe on ground. Then ohms with the power off.
Working, it reads
Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.
Dead, it reads
- Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
- Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
- Power off, input to output near 0 Ω: shorted.
- On the board:
- An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
- Compare:
- The same regulator on another rail or another board shows the right voltages and the right resistances.
- Watch for:
- Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
TC1301BJBDVMFprinted BJBDDFNMicrochipNot recordedDFNNot recordedMicrochip
Printed BJBD. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
- What it is
- Not recorded
- Maker
- Microchip
- Package
- DFN
- Pins
- Not recorded
- Details
- Linear voltage regulator with volatge detector: LDO, Dual out, Vo1/Vo2=2.4V(300mA)/3.2V(150mA)±2.5%, Vdet=2.5V±2.5%, +CE
- Source
- Published code list
Is it dead?
Voltage, board powered, black probe on ground. Then ohms with the power off.
Working, it reads
Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.
Dead, it reads
- Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
- Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
- Power off, input to output near 0 Ω: shorted.
- On the board:
- An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
- Compare:
- The same regulator on another rail or another board shows the right voltages and the right resistances.
- Watch for:
- Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
TC1301BJBEVMFprinted BJBEDFNMicrochipNot recordedDFNNot recordedMicrochip
Printed BJBE. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
- What it is
- Not recorded
- Maker
- Microchip
- Package
- DFN
- Pins
- Not recorded
- Details
- Linear voltage regulator with volatge detector: LDO, Dual out, Vo1/Vo2=2.4V(300mA)/3.2V(150mA)±2.5%, Vdet=2.4V±2.5%, +CE
- Source
- Published code list
Is it dead?
Voltage, board powered, black probe on ground. Then ohms with the power off.
Working, it reads
Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.
Dead, it reads
- Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
- Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
- Power off, input to output near 0 Ω: shorted.
- On the board:
- An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
- Compare:
- The same regulator on another rail or another board shows the right voltages and the right resistances.
- Watch for:
- Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
TC1301BJBFVMFprinted BJBFDFNMicrochipNot recordedDFNNot recordedMicrochip
Printed BJBF. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
- What it is
- Not recorded
- Maker
- Microchip
- Package
- DFN
- Pins
- Not recorded
- Details
- Linear voltage regulator with volatge detector: LDO, Dual out, Vo1/Vo2=2.4V(300mA)/3.2V(150mA)±2.5%, Vdet=2.6V±2.5%, +CE
- Source
- Published code list
Is it dead?
Voltage, board powered, black probe on ground. Then ohms with the power off.
Working, it reads
Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.
Dead, it reads
- Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
- Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
- Power off, input to output near 0 Ω: shorted.
- On the board:
- An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
- Compare:
- The same regulator on another rail or another board shows the right voltages and the right resistances.
- Watch for:
- Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
SMBJ8.5Aprinted BJ8.5ASMBTVS diode, 2 pins, SecosTVS diodeSMB2 pinsSecos
Printed BJ8.5A. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
- What it is
- TVS diode
- Maker
- Secos
- Package
- SMB
- Pins
- 2
- Source
- Published code list
Is it dead?
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.
SMBJ8.5CAprinted BJ8.5ASMBTVS diode, 2 pins, SecosTVS diodeSMB2 pinsSecos
Printed BJ8.5A. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
- What it is
- TVS diode
- Maker
- Secos
- Package
- SMB
- Pins
- 2
- Source
- Published code list
Is it dead?
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.
SMBJ85Aprinted BJ85ASMBTVS diode, 2 pins, SecosTVS diodeSMB2 pinsSecos
Printed BJ85A. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
- What it is
- TVS diode
- Maker
- Secos
- Package
- SMB
- Pins
- 2
- Source
- Published code list
Is it dead?
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.
SMBJ85CAprinted BJ85ASMBTVS diode, 2 pins, SecosTVS diodeSMB2 pinsSecos
Printed BJ85A. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
- What it is
- TVS diode
- Maker
- Secos
- Package
- SMB
- Pins
- 2
- Source
- Published code list
Is it dead?
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.
Did you find your part?
One code, several parts
Marking codes are not unique. In the standard code book, 6H on a SOT-23 is an NPN transistor, a varicap, an N-channel JFET, two digital transistors, a 3.6 V voltage detector: six parts from five makers. So a search shows the parts we hold under that code and under codes easily misread as it, with only the columns that tell them apart.
- NPN transistor
- Varicap
- N-channel JFET
- Digital transistor ×2
- 3.6 V voltage detector
When more than one is left
Tap Help me choose. Up to 4 quick answers: whether the part has failed, then what separates the parts left. Those get ranked with the reasoning and a test that settles it. That uses one identification: 2 a month are free without an account, and 3 with a free account.
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Tap the camera in the field. We read the characters, keep the ones we are unsure of, and search every reading. A photo too soft to read is turned back on your phone first; if it is the only one you can get, you can still send it.
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