Display Backlight Troubleshooting - Nokia 3155i Troubleshooting Manual

Nokia Customer Care
Secondary display connection

Display Backlight Troubleshooting

When troubleshooting the display backlight, make these common checks (see
• Perform visual inspection of LCD connector and LED Driver circuitry
• If the display backlight does not turn on, check VLED +(~12V) for the main
display; VLED 2+ for the secondary display and VLED – (~.5V) on display
connector for both
• If there, then you can assume the driver is working properly and the LED inside
the display might be faulty. Change display.
• Check VLED + and VLED – on Display Driver circuitry
• Check Dlight is enabled high (~4V) for secondary LCD. If not correct, check
UEMEK.
ISSUE 1 07/2005
Figure 19: Display Chips and Frequency
©2005 Nokia Corporation
3155/3155i (RM-41), 3152 (RM-61)
Baseband Description and Troubleshooting
V Flash 1
DIFF_ DA3
DIF_WRX
DIF_RDX
DIF_CLK
VIO
Main display connection
Company Confidential
LCD_CSX
LCD_CLK
LCD_ DA
Figure 20):
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