Ericsson T28S Troubleshooting Manual page 19

Trouble Shooting Guide, Standard
Fig. 5.1
Power up the board start and it up.
±
Measure the voltage at pin 10 of N750 (3.7 0.05 V).
If the voltage is incorrect, measure the resistances of L750 (7 ohms), C751 (>1 Mohm) and
the resistance from L750, at the pin close to C667, to VBATT (0 ohms).
If any of the L750 or C751 resistances are incorrect, replace the corresponding component.
If the resistance from L750 to VBATT is incorrect there is a foil damage, send the unit on
according to the local company directives.
If the voltage at pin 10 of N750 is correct, measure the voltage at pin 5 of N750 (2.70–
2.85V).
If the voltage at pin 5 of N750 is correct, replace C752.
If the voltage at pin 5 of N750 is incorrect, measure the resistance from C703, at the pin close
to C834, to pin 5 of N750 (0 ohm).
If the resistance is incorrect there is a foil damage, send the unit on according to the local
company directives.
Measure the resistance of R750 (18 kohms at board revision up to R1D, 22 kohms at board
revision R1E and later).
If the resistance is incorrect, replace R750.
If the resistance is correct, replace N750.
If the fault remains, send the unit on according to the local company directives.
4/00021-2/FEA 209 544/19 E 19(29)