Ericsson T18s Trouble-Shooting Instruction page 20

* If it isn't, replace D600 (class B, fig. 3.2).
• If the voltage is correct, measure the resistance of C692 (>200 kohms, fig. 3.4).
* If it's incorrect, replace C692 (class A).
* If the resistance is correct, check the voltages at N706 (pin 1 – GND, pin2 –
VBATT, pin 3 - ~3V output voltage, fig. 3.4).
* If VBATT or GND is missing there's a foil damage and the phone is to
be discarded.
* If the output voltage is incorrect, replace N706 (class A).
* If all the voltages are correct, measure the VRTC voltage at the positive
side of C720 (class A, fig. 3.6, ~3V).
* If the voltage is missing, replace V711 (class A, fig. 3.6).
* If the voltage is correct, measure the resistance from the positive side
of C720 (fig. 3.6) to the marked side of C692 (fig. 3.4, ~0 ohms).
* If the resistance is too high there's a foil damage and the phone is
to be discarded.
If the fault remains, send the phone to Advanced electrical repairs.
3.4.5 Doesn't start in the flash programmer.
Open the phone and check for liquid damages.
Make sure the pads for the battery connector and system connector aren't dirty, oxi-
dised or liquid damaged.
Put the board in the fixture, start it up and keep it running by keeping DCIO high.
Check the VDIG (~3.2V) and VCORE (~2.5V) voltages (fig. 3.3).
• If any of the resistances are too low, measure the resistance from it to ground
(VDIG>48 kohms, VCORE>40 kohms).
* If the resistance is correct, replace the corresponding regulator (VDIG –
N702, VCORE – N700, both of class A).
• If the resistances are correct, check the power reset voltage at C710 (fig. 3.4,
>3V).
* If the voltage is incorrect, replace C710 (class A).
* If it is correct, make sure there are no faulty solderings at D600 (fig. 3.2).
* If the solderings are correct, measure the amplitude (>0.6V p-p) of the
MCLK signal (master clock, 13MHz)at C680 (Fig. 3.4) using an oscillo-
scope or a diode probe (if possible).
* If the amplitude is correct, replace D600 (class B, fig. 3.2).
* If the amplitude is too low, replace C680 (class A, fig. 3.4).
4/00021-2/FEA 209 544/12.B
T18s, T18sc Standard Electrical Repairs
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