SMD code 138K
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.
138K on a chip resistor
138 kΩ
138 kΩ resistor
The K is both the decimal point and the multiplier: 138 kΩ.
Check it with a meter
Lift one end and measure across it. A good one reads 138 kΩ. Measuring it in circuit reads the parallel combination of everything around it, which is almost always lower, never higher: well above 138 kΩ on the board is a fault. Open, or well above 138 kΩ, means it has failed: burnt, cracked or corroded. That does not change what to fit: the marking still says 138 kΩ. A burnt resistor usually means the part it feeds drew too much, so find that before fitting a new one.
On a transistor or diode body (SOT-363), 138K is a part code instead. Those parts are listed below.
The only part printed 138K in our tables
SUM138K-C
- What it is
- MOSFET
- Maker
- SeCoS
- Package
- SOT-363
- Pins
- 6
- Source
- Manufacturer datasheet
Is it dead?
Diode range, part lifted. Test drain to source first, then short gate to source and test again.
Working, it reads
One way between drain and source reads about 0.4 to 0.9 V, the body diode, and the other way open. The gate reads open to both other pins.
Dead, it reads
- Drain to source the same both ways, near 0 V with a continuous beep, and still so after shorting gate to source: shorted. The classic failure.
- The gate reads low to source or drain: gate shorted.
- No body diode at all: failed open.
- On the board
- the gate usually has a resistor to the source, which reads as that resistor and is not a fault. Lift a leg to be sure.
- Compare:
- If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
- Watch for:
- The diode range can charge the gate enough to turn the part on, and then drain to source reads near 0 both ways on a good part. Short gate to source and test again before you condemn it.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
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