SMD code S4G
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 45 parts are ranked, with a meter test that settles it. It works on a dead part too.
The only part printed S4G in our tables
S4GC
- What it is
- Rectifier
- Maker
- YFW
- Package
- SMC
- Pins
- 2
- Details
- Rectifier diode
- Source
- Manufacturer datasheet
Is it dead?
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.
Was it this one?
Printed with a code easy to misread as S4G
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 S4G
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 8 more parts.
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