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SMD code R0

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.

R0 on a chip resistor

0 Ω

0 Ω resistor

The R stands in for the decimal point, which is how sub-ohm and fractional values are printed.

Check it with a meter

Lift one end and measure across it. A good one reads 0 Ω. Measuring it in circuit reads the parallel combination of everything around it, which is almost always lower, never higher: well above 0 Ω on the board is a fault. Open, or well above 0 Ω, means it has failed: burnt, cracked or corroded. That does not change what to fit: the marking still says 0 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, SMA, SOD-123W), R0 is a part code instead. Those parts are listed below.

4 parts are printed R0

Not sure which one you have?

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

  • BZD27C160P-MSOD-123FZener diode, 2 pins, Vishay
    What it is
    Zener diode
    Maker
    Vishay
    Package
    SOD-123F
    Pins
    2
    Details
    160 V Zener diode
    Source
    From the manufacturer's datasheet

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

    Datasheetfor BZD27C160P-M, opens in a new tab
  • BZX84-B56SOT-23Zener diode, 3 pins, Nexperia
    What it is
    Zener diode
    Maker
    Nexperia
    Package
    SOT-23
    Pins
    3
    Pinout
    • 1 anode
    • 2 not connected
    • 3 cathode
    Details
    56 V ±2% voltage regulator (Zener) diode
    Source
    From the manufacturer's datasheet

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

    Datasheetfor BZX84-B56, opens in a new tab
  • CJ3400SOT-23N-channel MOSFET, 3 pins, JSCJ
    What it is
    N-channel MOSFET
    Maker
    JSCJ
    Package
    SOT-23
    Pins
    3
    Details
    MOSFET, N-channel, 30 V, 5.8 A
    Source
    From the manufacturer's datasheet

    Is it dead? The meter test is below: N-channel MOSFET.

    Datasheetfor CJ3400, opens in a new tab
  • CJK3400SOT-23N-channel MOSFET, 3 pins, JSCJ
    What it is
    N-channel MOSFET
    Maker
    JSCJ
    Package
    SOT-23
    Pins
    3
    Details
    MOSFET, N-channel, 30 V, 5.8 A
    Source
    From the manufacturer's datasheet

    Is it dead? The meter test is below: N-channel MOSFET.

    Datasheetfor CJK3400, 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.

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.

N-channel MOSFET

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.

Printed with a code easy to misread as R0

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 R0

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.