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1 part is printed TK73. 1 printed with a similar-looking code.

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.

The only part printed TK73 in this package in our tables

TL4050C10QDBZ

What it is
Voltage reference
Maker
Texas Instruments
Package
SOT-23
Pins
3
Details
Precision Micropower Shunt Voltage Reference
Source
From the manufacturer's datasheet

Is it dead?

Voltage with the board powered; ohms from each pin to ground with it off.

Working, it reads

Supply pin at its voltage and the output doing what the datasheet says. Readings between pins depend on the part.

Dead, it reads

  • A pin near 0 Ω to ground or to the supply pin where an identical part does not read that: failed short.
  • Supply present, output stuck: failed, or its load has.
On the board:
A pin shorted to ground on the board can be anything on that net. Lift the pin to be sure.
Compare:
The surest reference is the same IC on a working board, measured pin by pin.
Watch for:
Its protection diodes can read like junctions between pins, even like a transistor. That proves nothing either way.

A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.

Datasheetfor TL4050C10QDBZ, opens in a new tab

Printed with a code easy to misread

This part is printed with a character that is easy to misread as what you typed. The odd one out is marked on each.

  • TL4050B50IDBZprinted TKT3SOT-23Voltage reference, 3 pins, Texas Instruments

    Printed TKT3 on the part. Easy to misread as TK73. Check that character with a loupe before you order anything.

    What it is
    Voltage reference
    Maker
    Texas Instruments
    Package
    SOT-23
    Pins
    3
    Details
    Precision Micropower Shunt Voltage Reference
    Source
    From the manufacturer's datasheet

    Is it dead?

    Voltage with the board powered; ohms from each pin to ground with it off.

    Working, it reads

    Supply pin at its voltage and the output doing what the datasheet says. Readings between pins depend on the part.

    Dead, it reads

    • A pin near 0 Ω to ground or to the supply pin where an identical part does not read that: failed short.
    • Supply present, output stuck: failed, or its load has.
    On the board:
    A pin shorted to ground on the board can be anything on that net. Lift the pin to be sure.
    Compare:
    The surest reference is the same IC on a working board, measured pin by pin.
    Watch for:
    Its protection diodes can read like junctions between pins, even like a transistor. That proves nothing either way.

    A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.

    Datasheetfor TL4050B50IDBZ, opens in a new tab

One code, several parts

Marking codes are not unique. In the standard code book, 6H on a SOT-23 is an NPN transistor, a varicap, an N-channel JFET, two digital transistors, a 3.6 V voltage detector: six parts from five makers. So a search shows the parts we hold under that code and under codes easily misread as it, with only the columns that tell them apart.

6Hon a SOT-23, in the code book
  • NPN transistor
  • Varicap
  • N-channel JFET
  • Digital transistor ×2
  • 3.6 V voltage detector

When more than one is left

Tap Help me choose. Up to 4 quick answers: whether the part has failed, then what separates the parts left. Those get ranked with the reasoning and a test that settles it. That uses one identification: 2 a month are free without an account, and 3 with a free account.

When you cannot read it

Tap the camera in the field. We read the characters, keep the ones we are unsure of, and search every reading. A photo too soft to read is turned back on your phone first; if it is the only one you can get, you can still send it.