Transistor C124

Hi guys,

I´m trying to find a problem at air conditioning Fujitsu board. I´ve been testing components and it has two transistor C124 which I guess they are 2SC124. When I measure them I only get one measuring point between B-E 1,8V in diode test, 43K in ohm test. Both transistors measure the same which makes me think they are good.

I can´t find datasheet to see if they have some passive components inside which avoid a normal measurement on them. Do you have any idea about it? Thanks.

Hi 2PM,

xxxC124 is a digital NPN bipolar junction transistor (BJT) with built in base and base emitter resistors. In the case of the C124, both resistors are 22K Ohms.

It was made by various manufacturers with different prefix xxx.

You can knock up your own C124 with a BC546 NBJT and a couple of 22K resistors. Other small signal NBJTs will do depending on your maximum collector voltage which is 50V for the xxC124.

Most manufacturers, ROHM for example, only supply the xxxC124 in surface mount.

spec







DATASHEET

Thank you very much, finally I found a bad 12V relay. Solved.