SMD code search: identify a part by its marking
3 printed with a similar-looking code.
Not sure which one you have?
Answer up to 4 quick questions and these 3 parts are ranked, with a meter test that settles it. It works on a dead part too.
Nothing is printed exactly BISC
These parts are printed with a character that is easy to misread as what you typed. The odd one out is marked on each.
TVS diode, all SMB, 2 pins. What differs:
BV-SMBJ15CAprinted B15CSMBBencent ElectronicsBencent Electronics
Printed B15C on the part. Easy to misread as BISC. Check that character with a loupe before you order anything.
- What it is
- TVS diode
- Maker
- Bencent Electronics
- Package
- SMB
- Pins
- 2
- Details
- Transient voltage supressor: Vrwm=15V, Vbr=16.7..21.1V, 22.3A, 600W(1ms), Bidir.
- 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.
P6SBMJ27CAprinted B15CSMBChenmko EnterpriseChenmko Enterprise
Printed B15C on the part. Easy to misread as BISC. Check that character with a loupe before you order anything.
- What it is
- TVS diode
- Maker
- Chenmko Enterprise
- Package
- SMB
- Pins
- 2
- Details
- Transient voltage supressor: Vbr=25.7..28.4V, Vrwm=23.1V, 11.2A, 600W(1ms), Bidir.
- 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.
P6SMBJ15Cprinted B15CSMBYeashinYeashin
Printed B15C on the part. Easy to misread as BISC. Check that character with a loupe before you order anything.
- What it is
- TVS diode
- Maker
- Yeashin
- Package
- SMB
- Pins
- 2
- Details
- TVS: 13.5..16.5V, 27A, 600W(1ms), Bidirectional
- 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.
1 more part has a code that begins with BISC: none in SMB, 1 with no package on record
Codes that begin with BISC
For a marking with its end worn or burnt off. Each one shows its full printed code.
1 part has no package on record. Nothing rules it out, so it stays.
2SB1560printed B1560PNP transistor, SankenPNP transistorSanken
Printed B1560. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
- What it is
- PNP transistor
- Maker
- Sanken
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Silicon PNP Epitaxial Planar Transistor
- Source
- Published code list
Is it dead?
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.
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.
When you cannot read it
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.
Get the app
The same search on your phone, and a camera with a light, zoom and tap to focus for a marking you cannot read. Sign in with your email address to use the same account.
- Coming soon to the App Store