SMD code 3GS
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 are printed 3GS
Not sure which one you have?
Answer up to 4 quick questions and these 2 parts are ranked, with a meter test that settles it. It works on a dead part too.
BC857CSOT-23PNP transistor, 3 pins, InfineonPNP transistorSOT-233 pinsInfineon
- What it is
- PNP transistor
- Maker
- Infineon
- Package
- SOT-23
- Pins
- 3
- Details
- -50 V PNP small-signal transistor, gain group C
- Source
- Published code list
Is it dead? The meter test is below: PNP transistor.
MURS340SSMBRectifier, 2 pins, VishayRectifierSMB2 pinsVishay
- What it is
- Rectifier
- Maker
- Vishay
- Package
- SMB
- Pins
- 2
- Details
- Diode: Rectifier, 400V, 3A, Vf<1.2V(3A)
- Source
- Published code list
Is it dead? The meter test is below: Silicon 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.
PNP transistor
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.
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.
Printed with a code easy to misread as 3GS
One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.
Codes that begin with 3GS
For a marking with its end worn or burnt off. Each code has a page of its own.
Codes not listed here are printed on 128 more parts.
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