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* If the resistance is correct, replace the corresponding regulator.
* If it's too low, send the phone to the next level.
• If any of the voltages are too high, replace the corresponding regulator.
Measure the VRAD, VVCO and VRPAD voltages (~3.8V, fig. 3.1).
• If any of the voltages are incorrect, measure the resistance from it to ground (>50
kohms).
* If the resistance is correct, replace the corresponding regulator (see fig. 3.1,
all of class A).
* If the resistance is too low, send the phone to the next level.
3.4.4 The phone runs as long as the On/Off key is
pressed.
Open the phone and check for liquid damages.
Make sure the system connector pads aren't damaged or burnt.
Mount the board in the fixture. Start it up and keep it running by keeping DCIO
high.
Measure the voltage at C692 (>3V, fig. 3.1).
• If it's correct, check the soldering at D600 pin 119 (fig. 3.1).
• If it's incorrect, measure the resistance of C692 (>200 kohms, class A)
* If the resistance is correct, measure the input voltage at N706 pin 2
(VBATT, fig. 3.2) and the output voltage at pin 3 (~3.5V). Make sure that
there's ground at N706 pin 1.
* If VBATT or ground is missing there's a foil damage and the phone is to
be discarded.
* If VBATT and ground are correct but not the output voltage, replace
N706 (class A, fig. 3.2).
* If they're all correct, measure the voltage at the positive side of the
backup capacitor, C720 (~3.2V, class A, fig. 3.2).
* If it's incorrect, measure the resistances of R720 (180 kohms, class
A, fig. 3.2) and R719 (47 kohms, class A, fig. 3.2).
* If they're correct, replace V711 (class A, fig. 3.2).
* If the voltage is correct, measure the resistance from the positive side
of C720 (fig. 3.2) to C692 (fig. 3.1, ~0 ohms).
* If it's incorrect there's a foil damage and the phone is to be dis-
carded.
If the fault remains, send the phone to the next level.
4/00021-2/FEA 209 544/3.D
SH888, S868, Standare Electrical Repair
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(66)
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