HP ProBook 4525s Maintenance And Service Manual page 22

Component
(2) RJ-11 (modem) jack (select models only)
(3) Optical drive (select models only)
(4) Optical drive light (select models only)
(5) AC adapter light
(6) Power connector
14 Chapter 2 External component identification
Description
Connects a modem cable.
Reads optical discs and, on select models, also writes to optical
discs.
Blinking: The optical drive is being accessed.
● On: The computer is connected to external power and the
battery is charging.
●
Off: The computer is not connected to external power.
Connects an AC adapter.