SMD code 127K
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.
127K is a capacitor marking
120 µF
120 µF capacitor, 10%
12 followed by the multiplier 7, in picofarads: 120 µF. Printed this way on film and larger ceramic capacitors; small chip ceramics are usually not printed at all. K is the tolerance, ±10%. The same marking also reads as 127 kΩ on a resistor, and nothing in the code says which; the body of the part does.
Other readings of the same characters, most likely first
- 127 kΩ resistor
Check it with a meter
Lift one end and measure it on a capacitance range. A good one reads close to 120 µF. In circuit the meter also sees everything connected across it, so the reading means little until it is out. A failed one usually reads near 0 Ω, or a steady low resistance, on the ohms range, often from a crack. On the board a shorted capacitor shorts its whole rail. A failed reading does not change what to fit: the marking still says 120 µF.
On a transistor or diode body (SOT-23), 127K is a part code instead. Those parts are listed below.
The only part printed 127K in our tables
MTN127KN3
- What it is
- N-channel MOSFET
- Maker
- CYStek
- Package
- SOT-23
- Pins
- 3
- Details
- 600 V, 0.04 A N-channel MOSFET
- 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
Red probe on the source, black on the drain: about 0.4 to 0.9 V, the body diode. Open the other way. The gate reads open to both other pins, both ways.
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. Often all three pins end up shorted together.
- No body diode at all: failed open.
- On the board
- the gate usually has a resistor to the source, so gate to source reads that resistor, which is not a fault. A drain short can be the load. 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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