Ericsson PF 768 Troubleshooting Instructions page 44

PF768, Standard Electrical Repairs
* If the VRPAD voltage is faulty or missing, proceed to chapter 3
("Doesn´t start"-fault).
* If it's correct, check the resistance from pin 2 of N452 to pin 1 of V706
(~0 ohms).
* If the resistance is too high it's probably the L450 (~0 ohms, class A,
fig. 8.3) that's faulty.
* If L450 isn't faulty or incorrectly soldered there's a foil damage
and the phone is to be discarded.
* If the VRPAD voltage at V706 is correct, measure the resistance from
VBATT to V706 pin 3 (~4.7 ohms, fig. 8.3 and 8.2).
* If the resistance is too high it's probably R652 (~4.7 ohms, class A, fig.
8.2) that's faulty.
* If the resistor isn't faulty or incorrectly soldered there's a foil damage
and the phone is to be discarded.
* If the resistance from VBATT to V706 is correct, replace V706 (class
A).
• If the voltage at pad 4 of H600 is correct, measure the resistance from H600 pad
1 to V606 pin 3 (~0 ohms, fig. 8.2).
* If the resistance is too high it's probably R653 (~0 ohms, class A, fig. 8.2)
that's faulty.
* If R653 isn't faulty or incorrectly soldered there's a foil damage and the
phone is to be discarded.
* If the resistance is correct, make sure pin 91 of D600 (fig. 8.3) is correctly
soldered.
* If it is correctly soldered, replace R651 (class A, fig. 8.3) and V606
(class A, fig. 8.2).
* If that doesn't help, replace D600 (class B, fig. 8.3).
4/00021-2/FEA 209 544/11.C
Fig. 8.3
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