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SMD code 12C

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.

12C on a chip resistor

13 kΩ

13 kΩ resistor, 1%

EIA-96 precision code: 12 selects 1.3 from the E96 series and C multiplies by 10000. These are 1% parts.

Check it with a meter

Lift one end and measure across it. A good one reads 13 kΩ within 1%. Measuring it in circuit reads the parallel combination of everything around it, which is almost always lower, never higher: well above 13 kΩ on the board is a fault. Open, or well above 13 kΩ, means it has failed: burnt, cracked or corroded. That does not change what to fit: the marking still says 13 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 (WSON, SMC), 12C is a part code instead. Those parts are listed below.

2 parts are printed 12C

Not sure which one you have?

Answer up to 4 quick questions and these 2 parts are ranked, with a meter test that settles it. It works on a dead part too.

all Vishay. What differs:

  • 1.5SMC12CASMCTVS diode, 2 pins
    What it is
    TVS diode
    Maker
    Vishay
    Package
    SMC
    Pins
    2
    Details
    1500 W TVS diode, bidirectional
    Source
    From the manufacturer's datasheet

    Is it dead? The meter test is below: TVS or ESD protection diode.

    Datasheetfor 1.5SMC12CA, opens in a new tab
  • 1 more part has no package on record
    • PLZ12CZener diode
      What it is
      Zener diode
      Maker
      Vishay
      Package
      Not recorded
      Pins
      Not recorded
      Details
      12 V Zener diode
      Source
      From the manufacturer's datasheet

      Is it dead? The meter test is below: Zener diode.

      Datasheetfor PLZ12C, opens in a new tab

Is it dead? One meter test per kind

Parts of the same kind are tested the same way, so each test is here once. Each part above points to its own.

TVS or ESD protection diode

Diode range, from the protected line to ground, part lifted if you can.

Working, it reads

A one-way part reads about 0.6 to 0.8 V forward and open in reverse. A two-way part reads open both ways. Arrays with several lines read as the datasheet's diagram draws them.

Dead, it reads

  • From the line to ground, the same reading both ways, near 0 V with a continuous beep: shorted.
  • A reading both ways on a one-way part: leaky.
  • A one-way part open both ways: failed open.
On the board
, a line reading shorted to ground can be this part or anything else on that line. Lift it: if the short goes with it, it has failed.
Compare:
The same part on the next line or connector pin is the healthy reading to compare with.
Watch for:
A two-way part reads open both ways when it is good, exactly like one that has failed open. The meter cannot tell them apart; an identical part on the next line can.

A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.

Zener diode

Diode range for the forward check, part lifted, red probe on the anode. A bench supply for the Zener voltage.

Working, it reads

About 0.6 to 0.8 V forward and open in reverse on the diode range. Its Zener voltage shows only on a supply: feed it through a resistor that sets about 5 mA, cathode to positive, read quickly, and it should hold near its rated voltage.

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, forward too: failed open.
  • Holds well off its rated voltage on the supply test: drifted.
  • A soft knee, or a voltage that creeps on the supply test: 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 meter's diode range stops at about 2 to 3 V, so almost every Zener reads open in reverse on it, good or bad; a 3 V meter may just show a 2.4 or 2.7 V part. Above about 3 V the meter cannot tell a Zener from a plain diode.

A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.

Printed with a code easy to misread as 12C

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 12C

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.