Nokia 105 Rm 908 Keypad Ways High Quality Review

Troubleshooting the keypad on a Nokia 105 (RM-908) typically involves identifying broken circuit paths ("ways") on the PCB and applying jumper wires to restore connectivity. Hardware Repair Guide (Keypad Ways & Jumpers)

If specific keys are not responding, the internal track or a series resistor on the PCB is likely damaged.

Tools Needed: A multimeter, soldering iron, thin jumper wire, and tweezers.

Testing Connectivity: Set your multimeter to Continuity/Buzzer mode. Place one probe on the non-working key's center or outer ring and the other on its corresponding resistor or IC pin.

Common Key Groupings: Keys on the RM-908 are often grouped in rows or columns. If a whole row is dead, check the common track leading to the CPU/Power IC. Applying Jumpers:

Find the break in the line by following the color-coded paths on a schematic diagram. nokia 105 rm 908 keypad ways

If a series resistor is found to have no continuity on one side, you can sometimes bypass it by shorting the two pads together to restore the signal.

For the Power Key, the center point provides the signal while the outer ring is ground. If it won't turn on, run a jumper from the power section's designated point directly to the center pad of the power key. Software & Basic Troubleshooting

If the hardware tracks are intact, the issue might be software-related or a simple settings lock.

Factory Reset: If the keypad is acting erratically, try a hard reset by typing *#7370# on the home screen. Use the default security code 12345 when prompted.

Security Lock: If you are locked out, you can try resetting the code by removing the battery to drain residual power, then powering it back on without touching any buttons for 15 minutes. Troubleshooting the keypad on a Nokia 105 (RM-908)

Keypad Sounds: To adjust or mute the tones, go to Menu > Settings > Tone settings > Keypad tones.

For detailed PCB layouts and specific point-to-point jumper diagrams, you can find visual guides on Pinterest or search for "RM-908 keypad jumper solution" on YouTube for step-by-step video walkthroughs.

Are you dealing with all keys not working, or just one specific row or button?

For repairing the Nokia 105 RM-908 keypad , common issues often involve specific keys failing due to broken circuit tracks or water damage. Technical solutions typically involve jumper wires to bypass damaged sections of the motherboard Common Keypad Jumper Solutions

Repair guides often focus on grouping non-working keys to identify the broken "way" or track: Power Button Issues Phase 2: Trace Repair (Jumping) If specific keys

: If the phone won't turn on, you may need a jumper from the power key contact point to a specific capacitor on the board. Specific Key Failures

**Keys 1, 4, 7, ***: Often share a common track that may require a jumper if the entire column fails. Keys 2, 5, 8, 0

: These keys are typically linked on a separate vertical way. Keys 3, 6, 9, # : Another common group for circuit failures. Keypad Backlight

: If keys work but don't light up, the issue is usually related to the keypad light IC or specific LEDs that need a jumper solution. Repair Visuals & Resources

For precise jumper placement, referring to a hardware schematic or visual diagram is essential to avoid short-circuiting the board.

Phase 2: Trace Repair (Jumping)

If specific keys remain dead after cleaning:

1. Locate the start point (Key Dome contact) on the PCB.
2. Locate the endpoint (Input pin on the Keypad Filter IC or CPU).
3. Check continuity with a multimeter. If open (no beep), the track is broken.
4. Jumper Method: Solder a thin wire from the Key Dome contact directly to the corresponding pin on the Keypad IC.

2. Keypad matrix and PCB layout (assumption)

• The keypad uses a matrix of rows and columns on the PCB; each key bridges a row to a column when pressed.
• Typical small feature phones have 4–6 column traces and 4–6 row traces depending on number of keys. For RM-908, assume a 5x4 (example) matrix covering numeric keys, navigation, and function buttons.
• Key components:
  • Elastomer conductive pads
  • Keypad PCB traces (ways)
  • Flexible connectors / FFC to mainboard (if separate)
  • Ground plane and vias
  • Contact pads for micrcontacts

Why Jumpers Fail (Pro Tips)

If you installed a jumper and the key still doesn't work, check these:

1. Wrong Polarity of Diode: Some keypad lines have ESD protection diodes. If the diode is shorted, the key will remain pressed or dead. Remove the diode and jumper past it.
2. Carbon Pad Wear: The black conductive pill on the rubber mat can wear out. Fix this by sticking a tiny piece of aluminum foil (from a gum wrapper) with superglue onto the rubber pad.
3. Soldering Temperature: The PCB of the RM-908 is low-grade phenolic. If you use 400°C heat, you will lift the pads. Stick to 330°C with leaded solder.
4. Track Hidden Under CPU: If an entire side of the keypad fails (e.g., left side buttons 1,4,7,*), the break is likely under the CPU (BGA). This requires reballing the CPU, which costs more than the phone's value. Advise the customer to buy a new phone.

4. Safety and preparation

1. Power off device and remove battery before any work.
2. Work in ESD-safe area.
3. Carefully remove back cover, battery, screws, and separate housing to access keypad PCB and mainboard.