Ericsson T18s Trouble-Shooting Instruction page 33

• If the PWM0 and PWM1 signals are missing, check the resistances of C634 and
C636 (both of class A and in fig. 5.2) to see if there's a short circuit in one or
both of them.
* If there is a short circuit, replace the corresponding capacitor.
* If there is no short circuit in any of the capacitors there's probably D600
(class B, fig. 5.2) that is faulty. Replace it.
If VLCD voltage is more than 6V, replace V608 (class A, fig. 5.2).
If VLCD voltage is less than 2.5V, check if the V608 and V611 (class A, fig. 5.2)
diodes are faulty (by measuring the voltage drop with a multimeter).
• If the diodes aren't faulty, replace C634 and C636 (class A, fig. 5.2).
If VLCD is ~4.9V, measure the voltage at pin 2 of V611.
• If it is ~3.7V, replace C634 (class A).
• If it is ~5.8V, replace C636 (class A).
* If VLCD still is incorrect, measure the resistance from VLCD to V608 pin
2 (~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.
4/00021-2/FEA 209 544/12.B
T18s, T18sc Standard Electrical Repairs
33
(60)