First, identify the keypad connector on the motherboard (usually a small ZIF connector or soldered flex cable interface). On the RM-908, the connector is a 16-pin surface-mount component.
Here is the factory Keypad to CPU mapping:
| Pin No. | Signal Name | Goes To (Component) | Function | |---------|-------------|---------------------|-----------| | 1 | KBR0 (Column 0) | CPU (Row Sense) | Keys: 4, 5, 6, * | | 2 | KBR1 (Column 1) | CPU | Keys: 1, 2, 3, # | | 3 | KBR2 (Column 2) | CPU | Keys: Left, Up, Down, Right, Call | | 4 | KBR3 (Column 3) | CPU | Keys: End/Power, Cancel/Back | | 5 | KBT0 (Row 0) | CPU (Column Drive) | Keys: 1, 4, Left, End | | 6 | KBT1 (Row 1) | CPU | Keys: 2, 5, Up, Cancel | | 7 | KBT2 (Row 2) | CPU | Keys: 3, 6, Down | | 8 | KBT3 (Row 3) | CPU | Keys: *, #, Right, Power | | 9 | GND | Ground | Common ground | | 10 | GND | Ground | Common ground | | 11-16 | NC / LED+ | Not connected / Backlight | Keypad backlight anode |
(Note: Actual pin numbers may vary slightly depending on board revision; always test continuity with a multimeter before jumping.)
If the motherboard trace is completely destroyed and the CPU pad is inaccessible, you can bypass the connector entirely:
Better approach: Replace the entire keypad flex if the flex itself is torn. The "ways" method is for motherboard-level faults only.
Published by: Mobile Repair Hub
Difficulty Level: Intermediate (Soldering and basic schematic reading required)
To get accurate keypad ways for Nokia 105 RM-908:
If you need a visual diagram of the keypad matrix or help mapping specific buttons, let me know — I can describe how to extract the row/column layout from your actual phone PCB step by step.
The Nokia 105 (RM-908) keypad layout works on a matrix system where keys are grouped into specific rows and columns
. When multiple keys in a single line stop working, it usually indicates a broken track or a faulty series resistor on the motherboard. Keypad Repair & Jumper Solutions nokia 105 rm 908 keypad ways
If you are troubleshooting a hardware failure, follow these steps to identify and fix the issue: Identify the Faulty Line : Use a multimeter in continuity (buzzer) mode
to check the connection between the inner and outer circles of the keys. Power Key Jumper
: The center point of the Power/End key provides the signal, while the outer ring is Ground. If the phone won't turn on, you can often find a direct jumper point near the power IC or a nearby test point. Series Resistors
: Each keypad line typically passes through a small series resistor before reaching the CPU. If you find a line with no value (open circuit), you can bypass or "short" these resistors to restore the connection. Matrix Groups
: Keys are often connected in groups (e.g., 1, 2, 3 or 4, 5, 6). If an entire row is dead, check the shared track for that specific group. Keypad Codes & Basic Functions
For software-related keypad issues or standard operations, use the following official Nokia guides and codes: Factory Reset to erase all data and restore settings. Default Security Code : The pre-set code for this model is Typing Shortcuts : Press the Special Characters : Press the Asterisk (*) Case Switch : Press the key repeatedly. Adjusting Keypad Tone Menu > Settings > Tone Settings > Keypad Tones to change the volume or mute button sounds. Common Troubleshooting
The Nokia 105 (RM-908) keypad functions through a matrix of tracks (lines) that connect to the main CPU/Power IC. When specific keys fail, it is usually due to a broken track or "way" that needs a jumper to restore the connection. Hardware Troubleshooting (Keypad Ways)
For the RM-908, the keypad is organized into "rows" and "columns." If multiple keys fail together (e.g., 1, 2, 3), it indicates a break in a shared line.
Multimeter Testing: Set your multimeter to Buzzer/Continuity mode. Test from the center point of a non-working key to the center point of another key in the same row/column to see if the track is continuous. Common Jumper Solutions:
Power Key: If the phone won't turn on, check the red-marked track for the power button. This line often runs through a small resistor near the CPU. First, identify the keypad connector on the motherboard
Shared Lines: If a group of keys like 4, 5, 6 fails, trace the common track. You may need to jump a wire from a working key in that group to the non-working ones.
IC Issues: Since the RM-908 uses a single integrated chip for keypad control, if tracing and jumping don't work, the CPU/IC may need to be re-balled or heated. Essential Keypad Shortcuts & Operations Key Combination Lock Keypad Select Go to > Lock keypad. Unlock Keypad Press the End key and select Unlock. Flashlight On From home screen, quickly press Scroll Up twice. Flashlight Off Press Scroll Up once. Switch Case Press # repeatedly to cycle through ABC, abc, and 123. Special Chars Press and hold *. Factory Reset Dial *#7370# (Default code: 12345). Nokia 105 (2023) User Guide - HMD
Repairing Nokia 105 (RM-908) Keypad Issues: A Comprehensive Jumper Guide
Is your Nokia 105 (RM-908) acting up with non-responsive keys or broken tracks? Whether it’s a single button or an entire row failing, hardware issues on this classic model are common but often repairable with the right jumper "ways".
This guide covers the essential steps for diagnosing and fixing keypad malfunctions on the RM-908. 1. Initial Troubleshooting
Before opening the device, rule out software or minor physical blocks:
Clean the Pads: Dirt or moisture often gets under the keypad membrane. Clean the gold contacts on the PCB with isopropyl alcohol.
Check Keyguard Settings: Ensure the keypad isn't simply locked by going to Menu > Settings > Security > Keyguard.
Factory Reset: If the keys work but the phone is "stuck," use the hard reset code *#7370# (default security code is 12345). 2. Identifying Hardware Failures
If cleaning doesn't work, you likely have a broken "way" or track. Technicians use a multimeter set to Buzzer/Diode mode to test continuity between the key pads and the CPU or surrounding resistors. Common Keypad Symptoms: If the motherboard trace is completely destroyed and
No Power-On: Often caused by a break in the Red Power Key line.
Partial Row Failure: If keys like 1, 2, and 3 fail simultaneously, there is a break in the common supply line for that row.
Short Circuits: When one keypress triggers multiple characters or a phone shutdown. 3. Jumper Solutions and "Ways"
The Nokia 105 RM-908 uses a series of resistors and direct lines to the main IC.
The Power Key: The center point of the power button carries the GR (Ground Resistance) value. If this track is broken, you can jump it directly from the power section components on the PCB.
Series Resistors: Each keypad line typically passes through a small series resistor. If you find a resistor with a signal on one side but not the other, you can carefully "short" (bridge) the resistor with a small wire to restore the connection.
CPU Reballing: In extreme cases where multiple lines are dead and tracks are intact up to the main IC, the chip itself may need reballing to restore contact. 4. Step-by-Step Repair Process Disassemble: Carefully remove the back cover and battery.
Test Tracks: Use a multimeter to find which specific "way" is missing its signal.
Apply Jumper: Using thin enameled copper wire, connect the dead pad to its corresponding test point or resistor.
Seal: Use a tiny bit of UV mask or tape to secure the jumper wire so it doesn't short against the metal shield.
You can find detailed visual jumper maps on tech forums or sites like Pinterest for RM-908 which often host specific track layouts. Nokia 105 (2023) User Guide - HMD
If you installed a jumper and the key still doesn't work, check these: