If the entire top numeric row goes dark, the trace connecting them has severed. The inner points of are chained together. If Key 1 is dead but Key 2 works, run a thin jumper wire from the inner pad of Key 2 to the inner pad of Key 1. Column-Based Failure (e.g., 1, 4, 7,
Some key points to note when working with the keypad on a Nokia 105 (RM-908):
| | | 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 | - | nokia 105 rm 908 keypad ways
Because the RM-908 utilizes a highly integrated single-chip PMIC/CPU layout, these tracks run directly through small surface-mount resistors (filters) straight beneath the main chip. If an entire line of keys fails (e.g.,
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 If the entire top numeric row goes dark,
Repair Application: If keys 1 , 2 , and 3 fail together but the Call Key works, scrape the trace line coming out of the Call Key and solder a jumper wire directly to the inner pad of key 1 . The Vertical Ring Tracks (Outer Rings) Left Selection ↔left-right arrow Call Key ↔left-right arrow 1 ↔left-right arrow 4 ↔left-right arrow 7 ↔left-right arrow * Column 2: Up Navigation ↔left-right arrow Down Navigation ↔left-right arrow 2 ↔left-right arrow 5 ↔left-right arrow 8 ↔left-right arrow 0 Column 3: Right Selection ↔left-right arrow End/Power Key ↔left-right arrow 3 ↔left-right arrow 6 ↔left-right arrow 9 ↔left-right arrow #
Both the row and column lines run directly through small surface-mount series resistors located right next to the central CPU. Column-Based Failure (e
Wipe away excess flux residue using IPA. Use a tiny droplet of UV-curable solder mask resin over the wire to hold it in place and prevent short circuits. Testing and Reassembly Nokia 105 - Legacy Portable Computing Wiki
A common failure pattern on the RM-908 motherboard involves the entire lower section going dead.
The black carbon pads under the rubber sheet or the metal domes become oxidized and dirty, blocking electrical contact.
operates on a matrix configuration split into inner dots (positive/signal) and outer rings (negative/ground loop). When a specific line on the motherboard fractures, it usually deactivates a cluster of keys instead of just one. Row / Column Group Associated Buttons sharing the same Track / Jumper Way Left Selection Key, Up Navigation, Right Selection Key Row 2 Call/Dial Key, Center/Down Navigation, End/Power Key Row 3 Key 1, Key 2, Key 3 Row 4 Key 4, Key 5, Key 6 Row 5 Key 7, Key 8, Key 9 Row 6 ), Key 0, Hash ( Step-by-Step Diagnostic Routine