Ericsson T18s Trouble-Shooting Instruction page 30

Clean the marked area using a brush and alcohol.
Measure the resistance from pad 3 of J602 to unmarked side of R635 (~0 ohms,
fig. 4.4 and 4.1).
Measure the resistance from pad 5 of J602 to unmarked side of R636 (~0 ohms,
fig. 4.4 and 4.1).
• If any of the resistances are incorrect there's a foil damage and the phone is to be
discarded.
Measure the resistances of R601 and R605 (both are ~1 kohms, of class A and in
fig. 4.2).
• If all the resistances are correct, check the solderings of N800 and D600 (fig.
4.2).
If the fault remains, send the phone to Advanced electrical repairs.
4.8 Mute fault.
Connect a call and measure the voltage between pin 4 (AGND) and pin 6 (Mute) of
J602 (~3.2V when a call is in progress, Fig. 4.4).
• If the mute voltage is correct the fault probably lies in the handsfree unit.
• If there's no mute voltage, open the phone and check for liquid damages, espe-
cially around the system connector pads.
Measure the resistance from pad 6 of J602 to ground (>100 kohms, fig. 4.4).
• If the resistance is too low, replace F605 (class A, fig. 4.7).
* If the resistance still is incorrect, replace D600 (class B, fig. 4.2).
Measure the resistance from pad 6 of J602 to pin 92 of D600 (~470 ohms).
• If the resistance is incorrect, replace R602 (class A, fig. 4.2).
* If the resistance still is incorrect there's probably a foil damage and the
phone is to be discarded.
• If the resistance is correct but the fault remains, replace D600 (class B, fig. 4.2).
4/00021-2/FEA 209 544/12.B
T18s, T18sc Standard Electrical Repairs
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