Manufacturing faults do (very occasionally) occur, usually in new equipment. If there is a fault in a new transistor, it will often show up in the first few hours of use. If it operates correctly for this period then the chances are that it will continue to do so.
Some of the key points to note and hints and tips for testing and fault-finding a transistor circuit such as a transistor radio with a multimeter.
Such details provide a deeper understanding and appreciation for Transistor Fault Diagnosis.
