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22.2 How to find the fault
Start the phone in the test program.
Go to MMI/Keyboard.
Press all keys to find which one that is faulty.
If one or more of the keys at the keyboard is faulty, go to section 22.2.1.
If any of the volume keys is faulty, go to section 22.2.2.
If the PTT button is faulty, go to 22.2.3
If the Alert button is faulty, go to 22.2.4
If the Speakerphone slide switch is faulty, go to 22.2.5
22.2.1 One or more of the keys is faulty
Open the phone; remove the dome foil according to mechanical repair guide and check for
liquid damage especially around the faulty keys.
No further action should be taken for a liquid damaged telephone.
Clean the pads of the keyboard thoroughly using alcohol.
Give the board power and start the board in the test program.
Try the function of the keyboard.
If the fault is okay, it was due to the dome foil.
Mount a new dome foil according to mechanical repair guide.
If the fault remains, check in the schematics how the faulty keys are connected, i.e. if there is a
connection in a row or a column between the faulty keys.
If all keys are faulty:
In EFRA is one button shown as pressed all the time and the rest as faulty, the fault usually is
due to a short circuit, caused by dirt of the faulty button, according to EFRA.
If all keys of a column are faulty:
The fault is due to D600, the soldering at D600 or a foil damage.
If one or more keys, but not all, of a row or a column is faulty:
The fault usually is due to a foil damage.
You can verify this by measuring the foil between the faulty key and the pin at the processor
corresponding to the row or the column of the faulty key.
You can also measure between the foil and a working key in the same row/column.
If only the NO key is faulty, the fault can be due to V701.
4/00021-3/FEA 209 544/18 B
Trouble Shooting Guide, Advanced
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