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SMD code U1G in SMA

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.

2 parts in SMA are printed U1G

Not sure which one you have?

Answer up to 4 quick questions and these 7 parts are ranked, with a meter test that settles it. It works on a dead part too.

  • MURS140SMAonsemiNot recordedonsemi
    What it is
    Not recorded
    Maker
    onsemi
    Package
    SMA
    Pins
    2
    Details
    Si-diode: U-Fast Rectifier, 283V, 1A, Vf<1,25V(1A), 50ns
    Source
    Published code list

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

  • SMAU1GSMAKECNot recordedKEC
    What it is
    Not recorded
    Maker
    KEC
    Package
    SMA
    Pins
    2
    Details
    Si-diode: U-Fast Recovery, 400V, 1A, Vf<1,3V(1A), <50ns
    Source
    Published code list

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

  • 5 more parts have no package on record. Nothing rules them out, so they stay.
    • MURS140-BSRectifier, Formosa MicrosemiRectifierFormosa Microsemi
      What it is
      Rectifier
      Maker
      Formosa Microsemi
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Rectifier diode
      Source
      Manufacturer datasheet

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

    • MURS140-BS-Q1Rectifier, Formosa MicrosemiRectifierFormosa Microsemi
      What it is
      Rectifier
      Maker
      Formosa Microsemi
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Rectifier diode
      Source
      Manufacturer datasheet

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

    • MURS140-SF-Q1Rectifier, Formosa MicrosemiRectifierFormosa Microsemi
      What it is
      Rectifier
      Maker
      Formosa Microsemi
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Rectifier diode
      Source
      Manufacturer datasheet

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

    • TCDU1GWRectifier, Taitron ComponentsRectifierTaitron Components
      What it is
      Rectifier
      Maker
      Taitron Components
      Package
      Not recorded
      Pins
      Not recorded
      Details
      Sintered Glass Passivated Ultra Fast Rectifiers
      Source
      Manufacturer datasheet

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

    • U10GHERectifier, Galaxy MicroelectronicsRectifierGalaxy Microelectronics
      What it is
      Rectifier
      Maker
      Galaxy Microelectronics
      Package
      Not recorded
      Pins
      Not recorded
      Details
      1A, 400V, 50ns, Surface Mount Fast Recovery Rectifiers
      Source
      Manufacturer datasheet

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

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.

Silicon diode

Diode range, part lifted or one leg off the pad. Red probe on the anode.

Working, it reads

About 0.5 to 0.8 V anode to cathode, and open the other way. Small switching diodes read about 0.6 to 0.7 V; large rectifiers can read a little lower.

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: failed open.
  • A reading the wrong way round as well: 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 three-pin body can hold two diodes. With a common pin they read two junctions from that pin, just like a transistor; in series they read two drops end to end. Test each pair the datasheet names.

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 U1G

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 U1G

For a marking with its end worn or burnt off. Each code has a page of its own.

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