Ericsson GF 768 Troubleshooting Manual page 48

Troubleshooting guide
• If the resistance increased, replace D600 (class B, fig. 9.2).
• 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. 9.8).
• If the resistance is too low, wash carefully and measure again.
• If the resistance still is too low, remove R605 (class A, fig. 9.5) and measure again.
• If the resistance increased, replace D600 (class B, fig. 9.2).
• 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. 9.5.
• If the voltages at R601 and R605 are correct, connect a handsfree to the system connector.
Measure the voltage at both sides of R601 (~0V, fig. 9.4) and at D600 pin 70 (~0V).
• If the voltage isn't correct, check the soldering at D600 pin 70 (fig. 9.2).
• If the soldering is correct, measure the resistance of R601 (table 9.1, class A).
• If the resistance is correct, replace D600 (class B).
Board
2/ROA 119 3283/7
2/ROA 117 3632/1
2/ROA 117 3748
2/ROA 117 3748
Table 9.1
• If the voltage is correct, check the solderings of N800 and D600 (fig. 9.2).
If the fault remains, send the phone to the next level.
9.5 Handsfree microphone out of order.
The fault occurs when there's an interrupt in the audiopath between the handsfree microphone (connected through
the system connector) and the N800. The audio path is shown in fig. 9.9.
Open the phone and check for water damages, especially around the system connector pads (X602) 1, 2 and 4 (fig.
9.8).
Measure the resistance of C850 and C851 (both >100 kohms, fig. 9.4, class A).
Make sure all the components in fig. 9.9 (R830, R825, R802, R805, C835, C810 and C812) are mounted on the
48
Revision Resistance of R601/R605
All 1 kohms
All 47 kohms
Up to R1C 47 kohms
R1C and above 100 kohms
Fig. 9.9
4/00021-2/FEA 209 544/6 C