Nokia 105 Rm 908 Keypad Ways [repack] -

For the Nokia 105 (RM-908), "keypad ways" refers to the hardware trace paths and repair solutions for non-functional keys. Technical troubleshooting for this model typically focuses on identifying broken tracks or faulty components that connect the keypad pads to the main CPU/Power IC. Hardware Repair & Jumper Solutions

Repairing the keypad usually involves tracing the connection between the inner (signal) and outer (ground/common) circles of each key pad.

Common Trace Failures: Keypad issues are often caused by corrosion or physical damage to the delicate copper tracks on the PCB. If a specific row or column of keys fails, it indicates a break in a shared supply line.

Jumper Technique: Technicians use a multimeter (set to "Buzzer" or "Continuity" mode) to test for Ground Resistance (GR) on the center points of the keys. If a point shows no reading, a thin copper "jumper" wire can be soldered from the non-working pad to a corresponding component or test point that still has a valid signal. nokia 105 rm 908 keypad ways

Series Resistors: The keypad lines often pass through small series resistors. If a line is dead on one side of a resistor but live on the other, the resistor can be bypassed (shorted) to restore the connection.

Power Key: The "On/Off" key has its own dedicated track leading directly to the power section of the IC. If the phone won't turn on but the battery is good, a jumper from the power key's middle point to its specific test point is often required. Keypad Software & Codes

If the hardware is intact but the phone is unresponsive or locked, specific keypad codes are used for maintenance: For the Nokia 105 (RM-908) , "keypad ways"

Security Lock: The default factory security code for the Nokia 105 is 12345.

Hard Reset: To erase all data and restore factory settings, enter *#7370# on the home screen.

Soft Reset: To restore settings without losing personal data, use *#7780#. General Keypad Usage For standard operation of the RM-908 keypad: Nokia 105 user guide: Keys and parts - HMD Phase 2: Trace Repair (Jumping) If specific keys

Note: You can set the phone to ask for a security code to protect your privacy and personal data. The pre-set code is 12345. Nokia 105 User Guide: Keypad - HMD

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.

Diagnosis Example:

  • If buttons 1, 2, 3, and # are dead: Check KBR1 (Column 1). That entire column trace is likely broken.
  • If buttons 4, 5, 6, and * are dead: Check KBR0 (Column 0).
  • If buttons 1, 4, Left, and End/Power are dead: Check KBT0 (Row 0).

This pattern allows you to isolate the faulty "way" to a single line rather than individual buttons.

1. Executive Summary

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.

Appendix B — Quick checklist for technicians

  • Backup mapping before repairs
  • Inspect for liquid damage first
  • Clean, then test, then repair
  • Reinforce repaired traces and provide strain relief
  • Test thoroughly before full reassembly

If you want, I can convert this into a printable one-page sheet or provide a diagram of the PCB keypad traces—tell me which format (PDF, A4 printable, or image).

5. Step-by-Step Repair Workflow

  1. Disassemble the phone completely. Separate the keypad membrane from the main PCB.
  2. Visual Inspection: Look for blackened/burnt contacts, corrosion (white/ green residue), or cracked solder joints on the UEM IC.
  3. Clean PCB Contacts: Use fiberglass pen or soft eraser, then IPA.
  4. Test Continuity (Diode Mode):
    • Identify which keys fail.
    • Refer to matrix map to determine if it's a Row issue (all keys in that row dead) or Column issue (all keys in that column dead).
    • Trace the faulty row/column from the keypad contact pad to the UEM.
  5. Bypass Broken Way:
    • If a trace is broken, scrape solder mask off a clean section of the trace near the keypad and near the UEM.
    • Solder a thin enameled copper wire (e.g., 0.1mm) between the two points.
  6. Test Keypad Membrane: Use multimeter probes on the carbon pills – resistance should drop to near 0 ohms when a key is pressed. If >500 ohms, replace membrane.

1. Device overview

  • Model: Nokia 105 (RM-908).
  • Keypad type: Elastomer (rubber) keypad with conductive pads interfacing a PCB keypad matrix.
  • Common fault modes: Non-responsive keys, intermittent keys, stuck keys, or multiple keys registering.