Ericsson T18s Trouble-Shooting Instruction page 26

Measure the voltage at both sides of R601 and at pin 70 of D600 (~3.1V, fig. 4.2,
you follow the PHFI signal).
Measure the voltage at both sides of R605 and at pin 67 of D600 (~3.1V, fig. 4.2,
you follow the EXTAUDI signal).
• If the voltage at R601 or R605 (both of class A) is too low only at one side (the
marked side), remove the resistor and measure the resistance from the marked
side to ground (fig. 4.2, >2 Mohms).
* If the resistance is correct, mount a new resistor where you removed the old
one.
* If the resistance is too low there's a short circuit in either the circuit board
or in D600. Replace D600 (class B, fig. 4.2).
* If that doesn't help there's a foil damage and the phone is to be dis-
carded,
• If the voltage is too low at both sides of R601 or R605, measure the resistances
of R635 and R636 (~22 kohms, class A, fig. 4.2).
* If the resistance of any of the resistors is incorrect, replace the correspond-
ing resistor.
4/00021-2/FEA 209 544/12.B
T18s, T18sc Standard Electrical Repairs
Fig. 4.3
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