Ericsson I 888 Trouble-Shooting Instruction page 13

3.4.3 Uses more than 200 mA.
Open te phone and check for liquid damages. Make sure the system connector pads
are not damaged or burned. Attach the board to the fixture. Keep it powered up with
DCIO high. Check the current consumption again, if it uses less than 200 mA, make
sure the gasket in the frame is fine, if it is change the display and the elastomer.
Measure the resistance between VBATT and ground. It should be larger than
1MOhm, if it is lower send the phone to the next repair level. Check VDIG and
VDSP (3.2 V, fig 3.1). If any of the voltages are too low, measure the resistance to
ground (VDIG >500 Ohm, VDSP >25 kOhm). If the resistance is correct, replace
the corresponding circuit (VDIG - N702 (class A) and VDSP - N701 (class A)). If
the resistance is too low, send the phone to the next repair level. If any of the volt-
ages are to high, replace the corresponding circuit. Measure the voltages on VRAD,
VVCO and VRPAD (3.8 V, fig 3.1). If one or more of the voltages are incorrect,
measure the resistance to ground (>50 kOhm). If the resistance is correct, replace
the corresponding regulator (fig 3.1, all are class A). If the resistance is too low,
send the phone to the next repair level.
3.4.4 The phone works as long as the On/Off-button is
pressed.
Open the phone and check for liquid damages. Make sure the system connector pads
are not damaged or burned. Attach the board to the fixture. Keep it powered up with
DCIO high. Measure the voltage on C692 (>3.0 V, fig 3.1). If there is a volt-
age,check the soldering at D600:119(fig 3.1). If there isn´t a voltage, check the
resistance of C692 (>200 kOhm, class A). If the resistance is correct, measure the
input voltage on N706:2 (VBATT, fig 3.2) and the output voltage N706:3 (3.5 V).
Make sure the ground of the regulator exist on N706:1. If VBATT or ground is miss-
ing, the board has to be discarded. If they are correct, replace N706 (class A). If the
output voltage is correct, measure the voltage to ground on the backup capacitors
plus side C720 (3.1 V, class A, fig 3.2). If there are no voltage, measure the resist-
ances over R720 (180 kOhm, class A,fig 3.2) and R719 (47 kOhm, class A,fig
3.2). Are they correct, replace V711 (class A,fig 3.2). If the output voltage is cor-
rect, measure the resistance between the plus side of C720 (fig 3.2) and C692 (fig
3.1), it should be approximately 0 Ohm. If the resistance is too high, is there a foil
damage and the phone has to be discarded. If the fault still remains, send the phone
to the next repair level.
3.4.5 The phone uses no current while the On/Off-but-
ton is being pressed.
Open the phone and check for liquid damages. Make sure the system connector pads
are not damaged or burned. Make sure the keyboard and the keyboard pads are clean
and not damaged, especially the On/Off-button (fig 3.3).
4-00021-2/FEA 209 544/5.C
I888, Standard Electrical Repairs
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