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SMD code T39

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.

3 parts are printed T39

Not sure which one you have?

Answer up to 4 quick questions and these 3 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • PJT7839SOT-363MOSFET, 6 pins, Panjit
    What it is
    MOSFET
    Maker
    Panjit
    Package
    SOT-363
    Pins
    6
    Source
    From the manufacturer's datasheet

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

    Datasheetfor PJT7839, opens in a new tab
  • PJT7839-AUSOT-363MOSFET, 6 pins, Panjit
    What it is
    MOSFET
    Maker
    Panjit
    Package
    SOT-363
    Pins
    6
    Source
    From the manufacturer's datasheet

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

    Datasheetfor PJT7839-AU, opens in a new tab
  • TPS73230DBVSOT-23-5LDO regulator, 5 pins, Texas Instruments
    What it is
    LDO regulator
    Maker
    Texas Instruments
    Package
    SOT-23-5
    Pins
    5
    Details
    Capacitor-Free, NMOS, 250mA, Low-Dropout Regulator With Reverse Current Protection
    Source
    From the manufacturer's datasheet

    Is it dead? The meter test is below: Voltage regulator.

    Datasheetfor TPS73230DBV, 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.

MOSFET

Diode range, part lifted. Test drain to source first, then short gate to source and test again.

Working, it reads

One way between drain and source reads about 0.4 to 0.9 V, the body diode, and the other way open. The gate reads open to both other pins.

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.
  • No body diode at all: failed open.
On the board
the gate usually has a resistor to the source, which reads as that resistor and is not a fault. 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.

Voltage regulator

Voltage, board powered, black probe on ground. Then ohms with the power off.

Working, it reads

Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.

Dead, it reads

  • Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
  • Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
  • Power off, input to output near 0 Ω: shorted.
On the board:
An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
Compare:
The same regulator on another rail or another board shows the right voltages and the right resistances.
Watch for:
Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.

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 T39

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.