Ericsson I 888 Trouble-Shooting Instruction page 11

3.2 Visual check.
Make an outer visual check. Make sure the battery screws are fine and fully
attached, the isolation plate by the battery screw is mounted, the volume buttons are
mounted and the system connector isn´t dirty or liquid damaged. Proceed to section
3.3.
3.3 Current consumption with the On/Off-but-
ton pressed.
Attach a dummy battery and start the phone using the On/Off-button while you
measure the current consumption.
• If the phone doesn´t use any current while pressing the On/Off-button, proceed
to section 3.4.5.
• If the phone uses more than 200 mA, remove the IRDA module and the gold
colored metal plate. Try to start the phone again. If the current consumption got
lower it was either the IRDA-module or the plate that was faulty. If the current
consumption still is too high proceed to section 3.4.3.
• If the phone uses between 1 and 200 mA, starts (asks about a SIM card, search-
ing for a net or something like that) and works as long as the On/Off-button is
being pressed, proceedto section 3.4.4.
• If the phone doesn´t start, try to program it in the flash programmer.
* If the phone doesn´t start in the flash programmer, proceed to section 3.4.1.
* If the phone doesn´t start after programing it or if it is troublesome in the
flash programmer, proceed to section 3.4.2.
* If the phone starts after programming it the fault is probably fixed, but to
eliminate the possibility of intermittent faults, check the board for liquid
damages or bad solderings at D600 and D610 (Fig 3.1).
3.4 Measuring at a powered circuit board.
3.4.1 Doesn´t start in the flash programmer.
Open the phone and check for liquid damages. Make sure the system connector pads
are not burned or damaged. Measure the resistance of R421 (0,1 Ohm, class B, fig
3.1). After every repair of the charging function, you have to verify the function
using the method mentioned in section 6.1.1. Attach the board to the fixture. Keep
the board powered up with high DCIO. 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, fig 3.1). If the resistance is too
low, send the phone to the next repair level. If any of the voltages are too high,
replace the corresponding circuit. Check Powerreset (PWRRST) at C710 (>3 V, Fig
3.1). If it is lower, measure the resistance of R725 (100 kOhm, class A, fig 3.1). Is
the resistance correct, replace C710 and N703, (both class A, fig 3.1.) Measure the
voltages on VRAD, VVCO and VRPAD (3.8 V, fig 3.1). If one or more voltages are
incorrect, measure the resistance to ground (>50 kOhm). If the resistance is correct,
4-00021-2/FEA 209 544/5.C
I888, Standard Electrical Repairs
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