Nokia 105 Rm 908 Keypad Ways Access

Important: Keep jumper wires as short as possible to prevent signal interference or ghost touches.

Understanding the matrix helps you quickly diagnose which row or column has failed. Below is the standard mapping for the Nokia 105 RM-908:

| | KBR0 (Col 0) | KBR1 (Col 1) | KBR2 (Col 2) | KBR3 (Col 3) | |--------|------------------|------------------|------------------|------------------| | KBT0 (Row 0) | 4 | 1 | Left | End/Power | | KBT1 (Row 1) | 5 | 2 | Up | Cancel/Back | | KBT2 (Row 2) | 6 | 3 | Down | - | | KBT3 (Row 3) | * | # | Right | - |

This report outlines the diagnostic and repair procedures for keypad failures in the Nokia 105 RM-908. Keypad issues in this model typically stem from one of three causes: physical damage (liquid/carbon wear), keypad filter IC failure, or PDSA/CPU disconnection. The "Keypad Ways" refer to the trace routes connecting the keypad membrane to the main logic board. nokia 105 rm 908 keypad ways

Tools needed:

Steps:

Example:

Key | Row pad | Column pad 1 | R1 | C1 2 | R1 | C2 3 | R1 | C3 4 | R2 | C1 5 | R2 | C2 6 | R2 | C3 7 | R3 | C1 8 | R3 | C2 9 | R3 | C3

Technicians should use a multimeter in continuity mode to trace connections. If a track is broken, use insulated jumper wire (0.10mm) to bridge the gap.

| Key | Connection Point A | Connection Point B | | :--- | :--- | :--- | | Call (Green) | Row 1 | Col 1 | | End (Red) | Row 5 | Col 1 | | D-Pad Up | Row 1 | Col 2 | | D-Pad Down | Row 2 | Col 2 | | D-Pad Left | Row 3 | Col 2 | | D-Pad Right | Row 4 | Col 2 | | D-Pad Center | Row 5 | Col 2 | | Soft Keys (L/R) | Row 1/2 | Col 3 | | Digit 1 | Row 1 | Col 4 | | Digit 2 | Row 1 | Col 5 | | Digit 3 | Row 1 | Col 6 | | Digit 4 | Row 2 | Col 4 | | ... | ... | ... | Important: Keep jumper wires as short as possible

(Note: Exact column/row assignments may vary slightly by PCB revision; always verify with a schematic diagram if available).

| Test Point Label | Signal | Location on PCB | |----------------|--------|------------------| | TP201 | COL0 | Near SIM holder | | TP202 | COL1 | Under keypad shield edge | | TP203 | COL2 | Adjacent to vibrator | | TP204 | COL3 | Near CPU pin 48 | | TP205 | ROW0 | Close to battery connector (-) | | TP206 | ROW1 | Below LCD connector | | TP207 | ROW2 | By microphone pads | | TP208 | ROW3 | Next to charging IC |

Continuity map (CPU to keypad pad):
Trace each from CPU ball (e.g., MT6250 balls: A5=ROW0, B5=COL0, etc.) to the physical keypad contact. Steps:

Set your multimeter to continuity (beep mode).