Ericsson SH 888 Trouble-Shooting Instruction page 13

3.4 Measuring at a powered circuit board.
3.4.1 Doesn't start in flash programmer.
Open the phone and check for liquid damages.
Make sure the system connector pads aren't damaged or burnt.
Measure the resistance of R421 (0.1 ohms, class B, fig. 3.1).
• If R421 is replaced, the charging function have to be verified using the method
mentioned in section 6.1.1.
* If it still is incorrect, send the phone to the next level.
Mount the board in the fixture. Start it up and keep it running by keeping DCIO
high.
Check VDIG and VDSP voltages (3.2V, fig. 3.1).
• If any of the voltages are too low, measure the resistance from it to ground
(VDIG >500 ohms, VDSP >25 kohms).
* If the resistance is correct, replace the corresponding circuit, VDIG - N702
(class A), VDSP - N701 (class A, both in fig. 3.1).
* If the resistance is too low, send the phone to the next level.
• If any of the voltages are too high, replace the corresponding circuit.
Check the powerreset (PWRRST) voltage at C710 (>3V, fig. 3.1).
• If it's lower, check R704 (~0 ohms, class A, fig. 3.1) and R725 (~100 kohms,
class A, fig. 3.1).
* If they are ok, first replace C710 and if it doesn't help, replace N703 (both
class A and in fig. 3.1).
Measure the voltages at VRAD, VVCO and VRPAD (~3.8V, fig. 3.1).
• If any of the voltages are incorrect, measure the resistance from it to ground (>50
kohms).
* If it's correct, replace the corresponding transistor (see fig. 3.1, all of them
class A).
* If the resistance is too low, send the phone to the next level.
4/00021-2/FEA 209 544/3.D
SH888, S868, Standare Electrical Repair
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