Led And Led Driver Troubleshooting - Nokia RM-555 Service Manual

RM-555
BB Troubleshooting and Manual Tuning Guide

LED and LED driver troubleshooting

Context
The device has two LED drivers that provide current for the keyboard and several LEDs (Charge, Send/end,
menu) . Brightness of backlights can be adjusted manually, and it affects the keypad. Keyboard backlights
and some LEDs can be turned ON/OFF separately but not without switching on the display lights.
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