Ericsson PF 768 Troubleshooting Instructions page 13

PF768, Standard Electrical Repairs
Give the board power and start it up by pressing the On/Off key (in the fixture or in
the back cover with a dummy battery inserted, mount system connector to make the
board lie steady in the back cover).
* If the phone still doesn't consume any current when the On/Off key is
pressed, proceed to section 3.4.2.
• If the phone consumes more than 200mA, remove the display and try again.
* If the consumption decreased it was the display that was faulty.
* If the consumption still is high, proceed to section 3.4.3.
• If the phone consumes 1-200mA, starts (asks for SIM, seeks net...) and runs as
long as you keep the On/Off key pressed but dies when you release the key, pro-
ceed to section 3.4.4.
• If the phone doesn't start, try to program it in the flash programmer.
* If the phone doesn't start in the flash programmer, proceed to section 3.4.5.
* If you can program the phone but it doesn't start afterwards or if the phone
is troublesome in the flash programmer, proceed to section 3.4.6
* If the phone starts once it's programmed in the flash programmer it proba-
bly isn't a faulty phone. To eliminate intermittent faults, check the board for
liquid damages and check if the D600, D610 and D620 (fig. 3.2) chips are
correctly soldered.
3.4 Measuring a powered board.
3.4.1 Consumes power immediately when battery is
inserted.
Open the phone and check for liquid damages.
Make sure the battery and system connector pads aren't liquid damaged, dirty or
oxidised.
Remove the dome switches. Clean the keypads using alcohol and a brush.
Put the board in the fixture without starting it up.
Measure the VDIG, VANA, VDSP, VRAD, VVCO and VRPAD feed voltages
(~0V).
Fig. 3.1 shows the measuring point for VRAD (P501) and fig. 3.3 show the measur-
ing point for VDIG.
4/00021-2/FEA 209 544/11.C
13
(68)