Testing procedures for the 2N4124 NPN transistor.
1. Using the HP 34401 multimeter press the "Cont" button to place the unit in Continuity mode.
2. Test the Base – Collector forward junction.
a. Multimeter Lead configuration.
b. Positive: Base “center pin”
c. Negative: Collector “right pin with markings facing up.”
d. Passing result ~730Ω
3. Test the Base – Emitter forward junction.
a. Multimeter Lead configuration.
b. Positive: Base “center pin”
c. Negative: Collector “left pin with markings facing up.”
d. Passing result ~730Ω
4. Test the Base – Collector reverse junction.
a. Multimeter Lead configuration.
b. Negative: Base “center pin”
c. Positive: Collector “right pin with markings facing up.”
d. Passing result OPEN
5. Test the Base – Emitter reverse junction.
a. Multimeter Lead configuration.
b. Negative: Base “center pin”
c. Positive: Collector “left pin with markings facing up.”
d. Passing result OPEN
6. Steps 2-5 must have a passing result to qualify a passing transistor.