This post explains for the SCR.
The Part Number is C107.
The function of this semiconductor is Silicon Controlled Rectifier.
Manufacturer: Digitron Electronic
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Description
C107 is a kind of SCR ( Silicon Controlled Rectifier). Flat Pack Design, Up to 600 Volts 4 Amperes (RMS).
SCRs are widely used in power control and regulation applications, such as lighting and heating control, motor control, battery chargers, and AC-to-DC power conversion, due to their high voltage and current handling capabilities, fast switching speeds, and high reliability.