Nokia 105 Rm 908 Keypad Ways Best

Here’s an informative guide regarding the Nokia 105 (RM-908) keypad ways — a term commonly used in mobile hardware repairing to refer to the track paths (circuit traces) and testing points for the keypad buttons on the phone’s PCB (printed circuit board).

Solution B: Jumper to CPU/Filter

Often, the trace breaks between the keypad contact and the protective filter. nokia 105 rm 908 keypad ways

1. Identify the specific button that isn't working (e.g., the "Call" button).
2. Find the schematic point for the Call button (e.g., it connects to Row 1 and Col 1).
3. If Row 1 is broken, find any other working point on Row 1.
4. Solder a thin wire from the non-working contact point to the identified Row/Col test point on the motherboard.

Row lines (example – not official, but typical for similar models)

• ROW1 → Keypad row 1 (keys: 1, 2, 3)
• ROW2 → Keypad row 2 (keys: 4, 5, 6)
• ROW3 → Keypad row 3 (keys: 7, 8, 9)
• ROW4 → Keypad row 4 (keys: *, 0, #)
• ROW5 → Navigation + soft keys

Step 2: Hardware Inspection & Jumper Solutions

If cleaning didn't help, you likely have a broken trace on the motherboard. Here’s an informative guide regarding the Nokia 105

Tools Needed:

• Multimeter
• Soldering iron (fine tip)
• Jumper wire (very thin insulated wire)
• Flux and Solder
• Schematic Diagram (for reference)

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.