SMD code 38W
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 4 parts are ranked, with a meter test that settles it. It works on a dead part too.
The only part printed 38W in our tables
PMBFJ108
- What it is
- JFET
- Maker
- NXP
- Package
- SOT-23
- Pins
- 3
- Details
- N-channel junction FETs
- Source
- An older or alternative marking, from a published code list
Is it dead?
Ohms range for drain to source, diode range for the gate, part lifted.
Working, it reads
Drain to source conducts both ways at a few hundred ohms, depending on the part, and some meters beep on it. The gate reads one junction to drain and to source, about 0.6 to 0.7 V, and open the other way.
Dead, it reads
- The gate the same both ways to drain or source, near 0 V with a continuous beep: gate shorted.
- Drain to source open: the channel has failed open.
- 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:
- Drain to source resistance varies from part to part. An identical part elsewhere on the board shows what is normal.
- Watch for:
- A good channel can beep like a short between drain and source. That is normal; the gate junction says whether it has failed.
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 38W
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 38W
For a marking with its end worn or burnt off. Each code has a page of its own.
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