Keyboard - Ericsson I 888 Trouble-Shooting Instruction

I888, Standard Electrical Repairs

8 Keyboard

8.1 Type of keyboard fault.
Put in a Sim card and a fully charged battery. Start the phone with the On/Off but-
ton. If it doesn´t start, proceed to chapter 3 ("Doesn´t start"-fault). Press all buttons
(remember the volume buttons) and verify which doesn´t work. This is an easy way
to do the verification: go to Menu/Settings/Key sound and choose Click. press the
buttons 1,2,3.. ...*,0,#. You should hear a click sound and the corresponding figure
shown in the display when you press each button. Then press Yes, No, Clr, "<" and
">". When pressing "Yes" the phone tries to make a call, press "No" and the phone
should disconnect the call, press "<" or ">" and you scroll the menues and "clr"
clears the display from the figures that came up. Press the two volume buttons, you
should hear a click sound each time. If one or both volume buttons are faulty, pro-
ceed to section 8.2. Close the flip over the keyboard, you should hear a click sound
just before it is fully closed. If there is no click sound when you close the flip, pro-
ceed to section 8.3. If one or more of the buttons are faulty, proceed to section 8.4.
8.2 The volume buttons are faulty.
Open the phone and check for liquid damages, especially around X820 (Fig 8.1).
Change the flex film for the volume buttons, put the phone together and try again.
C658
C687
X820
C688
3
C659 2 1
C689
C657
Fig 8.1
Measure the resistance between the pads on X820 to ground. All three should have a
resistance larger than 1 MOhm. If the resistance is lower, proceed to point 1 other-
wise proceed to point 2.
1. If the resistances are too low replace as follow; X820:1 replace C659 and C689;
X820:2 replace C658 and C688; X820:3 replace C657 and C687. (all capacitors are
class A, Fig 8.1). If the fault remains, replace D600 (class B, Fig 8.2).
2. Check the solderings on D600:122-123 (Fig 8.2) and D600:128. Measure the
resistance on the foil between X820:1-D600:122, X820:2-D600:128 and X820:3-
D600:123. If there is a damage in the foil the board has to be discarded.If no fault is
found replace D600 (class B).
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