SMD with 43 printed on it need help identifying

[DarkZero]

Hello all!

i think this part is transistor with built in resistors but i cant seem to find data sheet and i have few questions about this kind of transistors mainly hop to decide on replacement of such and how to test them.

in circuit base of the transistor goes to micro controller and what i think is collector goes to Z3M triac, triac is in short circuit but before i change it i measured base to gnd and +5v no shorts there so i guess micro is alive. now i need to make sure transistor is working and if its not what replacement to use if anyone could help my friend would be one happy person if we fix it.

[fra.gherard]

hi, look here: http://www.s-manuals.com/smd/43
it's a SOT23 package, all results for SOT23 are BAS40 schottky diodes.
put your DMM in diode test and try to measure the component how indicated in page 2, pin 1 anode-pin 3 katode. pin 2 not connected. if you read about 0.2 - 0.3V maybe is a BAS40

[Brumby]

If you're right about the BAS40 - then all you then need to do is figure out which configuration is inside:


I couldn't see it, but I didn't check all the datasheets.

[Back2Volts]

That list of 43s has a digital transistor in UMT3F package, which I wonder how close it is to the SOT23.  The transistor is a DTC143XUB from ROHM.

But the Z3M TRIAC has a 3mA sensitivity, so it could possibly be driven directly by the MCU.

[Brumby]

That list of 43s has a digital transistor in UMT3F package, which I wonder how close it is to the SOT23.

The UMT3F package body is 2.0mm long, the SOT23 is 3.0mm.

[fra.gherard]

if it is a BAS40, is only a BAS40, the other types haven't 43 marking (44-45-46).
but can be a npn digital transistor DTC143 series. here's datasheet http://rohmfs.rohm.com/en/products/databook/datasheet/discrete/transistor/digital/dtc143x.pdf
try to take the measures of the component and compare it with the dimensions indicated in datasheet. so, you will find how package it is, and which inner circuit do you have