Ericsson GF 768 Troubleshooting Manual page 32

Troubleshooting guide
• If there's voltage at one of the measuring points, replace the corresponding regulator. VDIG – N702, VANA
– N700, VDSP – N701, VRAD – N453, VVCO – N451 and VRPAD – N452 (all of them class A).
• If there's voltage at all of the measuring points, measure REGON at V702 pin 2 and 3 (fig. 6.3, ~0 V).
• If there's no voltage at V702 pin 2 it means that the REGON signal comes from one of the regulators or
from V704, V708 or V709 (fig. 6.6). V708 and V709 aren't used in the 2/ROA 117 3748/2 boards (all revi-
sions) and aren't mounted. Replace one component at a time and check after every switch.
• If there's voltage at both the pins measured (2 and 3) of V702 there's a short circuit at the On/Off pads. It's
almost always crumbs from the dome foil which is easily washed away with alcohol and a brush.
If the fault remains, send the phone to the next level.
32
Fig. 6.8
Fig. 6.9
4/00021-2/FEA 209 544/6 C