Keyboard; Display And Keyboard Backlight - Nokia RM-57 Service Manual

RM-57/58
System Module
2 Normal Partial mode, 260k colors but only part of the display is active
The module includes:
• FPWB foil including connector and discretes and driver circuits
• display panel (glass)
• drivers including display controller and 176 x 208 x 18 bits RAM
• backlight system: lightguide, LEDs and necessary optical sheets
• supporting mechanics
• metal frame (stainless steel)
• plastic frame
The interconnection between the LCD module and the Nokia engine is implemented with a 24-pin board-to-
board connector.
Display is controlled via MeSSi-8 interface by Helen3. All MeSSi-8 signals go through the EMC filtering ASIPs.
The display module does not require any tunings in service.

Keyboard

The device keyboard is connected to the main PWB with a board-to-board connector.
The keymatrix has six rows and four columns. The voice key on the main PWB and the navigation key are
connected to the same keymatrix.
Row0
Row1
Row2
Row3
Row4
Row5
Row6

Display and keyboard backlight

The device has one Led Driver (SMPS) that is used to drive both display and keyboard LEDs.
Both display LEDs (4pcs) and keyboard LEDs (4pcs) are connected in series.
Current adjustment of the driver is done from the display LED branch, and keyboard current also depends on
the display brightness.
In a typical use case, keyboard LEDs are turned ON only in dark ambient lighting conditions.
Control signals for LED driver are:
GenOut1
GenOut2
Issue 1
Table 18 Keymatrix
Col3
Right
Down
8
6
#
4
Apps
From
TAHVO
TAHVO
Company Confidential
Copyright ©2005 Nokia. All Rights Reserved.
Col2
Left
Up
3
1
Clear
To
R2302 (10k)
R2301 (4k7)
Col1
Right soft key
Send
2
*
Voice
Edit
Voltage
0V / 1.8V
0V / 1.8V
Nokia Customer Care
Col0
Left soft key
Select
7
5
9
End
0
Function
Maximum current
control (0V ->max
curr.)
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