SMD code C401
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.
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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.
The only part printed C401 in our tables
STC401F
- What it is
- NPN transistor
- Maker
- Kodenshi AUK
- Package
- SOT-89
- Pins
- 3
- Details
- NPN transistor: GP, HV, 80V, 1A, 1W, B=200..500, 160MHz
- Source
- Published code list
Is it dead?
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.
Was it this one?
Printed with a code easy to misread as C401
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 C401
For a marking with its end worn or burnt off. Each code has a page of its own.
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