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SMD code 757A

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.

757A on a chip capacitor

750 µF, 10 V

750 µF, 10 V tantalum capacitor

A moulded tantalum capacitor: 757 is the capacitance in picofarads (750 µF) and A is the rated-voltage code (10 V).

Check it with a meter

Lift one end and measure it on a capacitance range. A good one reads close to 750 µF. In circuit the meter also sees everything connected across it, so the reading means little until it is out. It is polarised: the band on the body marks the positive end, and a tantalum fitted backwards fails short, sometimes with a flame. A failed tantalum usually reads near 0 Ω both ways, often with a burnt or cracked body. A failed reading does not change what to fit: the marking still says 750 µF, 10 V. Fit the same capacitance at the same or a higher voltage.

On a transistor or diode body (SMA), 757A is a part code instead. Those parts are listed below.

2 parts are printed 757A

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.

Zener diode, all SMA, 2 pins, all Taiwan Semiconductor.

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.

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