User Guide

PAMS
Technical Documentation
NHD–4
Disassembly & Troubleshooting
Page 9
Original 11/97
Phone takes all available current
If phone takes all available current, the problem can be caused by bad
solder joints in PSL_+3V(N500), components around it and bottom
connector(X701).
Phone does not take current at all
If phone does not take current at all, check the following things:
– solder joints in PSL_+3V(N500)
– VBATT voltage should be available in pins 5 and 20 of PSL_+3V(N500),
if connections of PSL_+3V(N500) are OK and VBATT in pins 5 and 20 are
OK, change PSL_+3V(N500).
Current consumption OK during power–up, then fail
If the phone starts almost normally, but after few seconds all circuits are
powered down, the power–down, could be caused by lack of watchdog
signal from MCU(D706) to PSL_+3V(N500) . There are three major things
to be checked in this type of situation. First, check power distribution to all
baseband–main components. Then check that clocks are delivered to
CDRFI(N700), ASIC(D704), DSP(D705) and MCU(D706). If everything is
OK, check RESET status of circuitry mentioned above.
Checking the baseband power distribution
Before voltage measurements, power–down of PSL_+3V(N500) must be
prevented. This is done by shorting the watch–dog timing capacitor C507
with a wire soldered from one end of the capacitor to the other.
1.Check PSL_+3V(N500) output voltages pins 4, 21,16, 2, 24 and 1.
Expected value is around 3.15V. Also, check voltage in pin 12 (DETIN) to
be between 1.46V and 1.72V.
2.Check MCU(D706) supply voltage VL1(3.15V) on pins 5 and 42. Check
VREF (3.15V) voltage on MCU(D706) pin 60. Check voltages of
MCU(D706) related memory components: FLASH(D709) pins 30, 31 and
11; RAM(D700) pin 28; and EEPROM(D703) pin 7.
3.Check ASIC(D704) supply voltage VL1(3.15V) on pins 13, 22, 27, 44,
60, 65, 74, 88,103, 109, 117, 132, 146, 151, 161, and 176.
4.Check DSP(D705) supply voltage VL2(3.15V) on pins 8, 11, 36, 39, 49,
64, 76, 87 and 90. VL2(3.15V) is also fed to DSP RAM (D707) to pin 11
and 33.
5.Check CDRFI(N700) supply voltage VL3(3.15V) on pins 32, 33, 60, 62,
2, 6, 8 and 19.
6.Check supply voltages of audio CODEC(N600). VA2(3.15V) is fed to
pins 2 and 3. VL1(3.15V) is connected to pin 15.