SMD code P12
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.
P12 on a chip capacitor
0.12 pF
0.12 pF capacitor
The p is both the decimal point and the unit: 0.12 pF.
Check it with a meter
Lift one end and measure it on a capacitance range. A good one reads close to 0.12 pF. 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 0.12 pF.
On a transistor or diode body (SOT-23-5, SMA, SOT-23), P12 is a part code instead. Those parts are listed below.
The only part printed P12 in our tables
MMBD3004C
- What it is
- Switching diode
- Maker
- Panjit
- Package
- SOT-23
- Pins
- 3
- Source
- From the manufacturer's 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.
Codes that begin with P12
For a marking with its end worn or burnt off. Each code has a page of its own.
Open this in the search to correct a character or try another package.