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SMD code JY

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.

2 parts are printed JY

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.

Switching diode, 3 pins. What differs:

  • BAV199SOT-23Infineon
    What it is
    Switching diode
    Maker
    Infineon
    Package
    SOT-23
    Pins
    3
    Details
    Switching diode, 70 V, 215 mA
    Source
    From the manufacturer's datasheet

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

    Datasheetfor BAV199, opens in a new tab
  • BAV199WSOT-323Diotec
    What it is
    Switching diode
    Maker
    Diotec
    Package
    SOT-323
    Pins
    3
    Details
    SMD Small Signal Diodes
    Source
    From the manufacturer's datasheet

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

    Datasheetfor BAV199W, 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.

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.

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