Ericsson PF 768 Troubleshooting Instructions page 25

PF768, Standard Electrical Repairs
• If the resistance is too low, wash carefully and measure again.
* If the resistance still is too low, remove R601 (class A, fig. 4.3) and measure
again.
* If the resistance increased, replace D600 (class B, fig. 4.2).
* If the resistance didn't increase when removing the R601 resistor or if it
didn't help to replace D600, send the phone to the next level.
Measure the resistance from X602 pad 3 to ground (>100 kohms). Make sure there's
no dirt or oxide between the components at the marked area (fig. 4.8).
• If the resistance is too low, wash carefully and measure again.
* If the resistance still is too low, remove R605 (class A, fig. 4.5) and measure
again.
* If the resistance increased, replace D600 (class B, fig. 4.2).
* If the resistance didn't increase or if it didn't help to replace D600, send
the phone to the next level.
If all of the above measured resistances are correct but anyone of the voltages at
R601 or R605 are too low anyway, it usually is because of a short circuit caused by
dirt between the components in fig. 4.5.
If the voltages at R601 and R605 are correct, connect a handsfree to the system con-
nector.
Measure the voltage at both sides of R601 (~0V, fig. 4.3) and at D600 pin 70 (~0V,
fig. 4.2).
• If the voltage isn't correct, check the soldering at D600 pin 70 (fig. 4.2).
* If the soldering is correct, measure the resistance of R601 (~1 kohms, class
A).
4/00021-2/FEA 209 544/11.C
Fig. 4.6
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