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SMD code 20y

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.

20y on a chip resistor

1.58 Ω

1.58 Ω resistor, 1%

EIA-96 precision code: 20 stands for 158 in the E96 table, and the letter Y is the multiplier, × 0.01. These are 1% parts.

Check it with a meter

Lift one end and measure across it. A good one reads 1.58 Ω within 1%. Measuring it in circuit reads the parallel combination of everything around it, which is almost always lower, never higher: well above 1.58 Ω on the board is a fault. Open, or well above 1.58 Ω, means it has failed: burnt, cracked or corroded. That does not change what to fit: the marking still says 1.58 Ω. 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-23-5, SOT-23, SOT-89-5), 20y is a part code instead. Those parts are listed below.

16 parts are printed 20y

Not sure which one you have?

Answer up to 4 quick questions and these 16 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • Z02W20VYSOT-23Zener diode, 3 pins, KECZener diodeSOT-233 pinsKEC
    What it is
    Zener diode
    Maker
    KEC
    Package
    SOT-23
    Pins
    3
    Details
    Z-diode: 19.48..20.46V, Izt=5mA, Zzt=25Ω, 200mW
    Source
    Published code list

    Is it dead?

    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.

Did you find your part?

Open this in the search to correct a character or try another package.