Check The Solderings Of N800 (Fig - Ericsson PF 768 Troubleshooting Instructions

PF768, Standard Electrical Repairs
* If the resistance is correct, replace D600 (class B).
• If the voltage is correct, check the solderings of N800 and D600 (fig. 4.3 and
4.2).
If the fault remains, send the phone to the next level.
4.5 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. 4.7.
Open the phone and check for liquid damages, especially around the system connec-
tor pads (X602) 1, 2 and 4 (fig. 4.6).
Measure the resistance of C850 and C851 (both >100 kohms, fig. 4.3, class A).
Make sure all the components in fig. 4.7 (R830, R825, R802, R805, C835, C810
and C812) are mounted on the circuit board (fig. 4.3).
Check the solderings of N800 (fig. 4.3).
Give the board power and start it up by pressing the On/Off key without the system
cable connected.
Measure the voltage at the marked side of R825 (~3.1V, fig. 4.3).
• If there isn't any voltage or if it is incorrect, check the VANA voltage at the
marked side of R830 (fig. 4.4).
* If the VANA voltage is incorrect, proceed to chapter 3 ("Doesn´t start"-
fault).
* If VANA is correct, check the resistances of R830 (~470 ohms), R825 (3.3
kohms) and C835 (>1 kohms, all of class A and in fig. 4.3).
4/00021-2/FEA 209 544/11.C
Fig. 4.7
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