No Turn On - Debug Procedure; Internal Charger Test Debugging - Motorola V120e Service Manual

120e
TROUBLESHOOTING
The goal in trouble shooting is to quickly nar-
row down the possibilities to isolate a failure
to a single faulty component. This is espe-
cially important before deciding to replace a
large IC, filter or any component that is diffi-
culty or risky to replace. Sometimes the prob-
lem will be visually obvious. For example: a
cold solder joint, cracked chip, tombstone
parts etc., other times it will be necessary to
take some measurements.
NO TURN ON – DEBUG PROCEDURE
• Visual check – look for any damaged parts,
unsolder, Cold solder or missing parts
• Checking for short circuits – apply 4.4V
power supply with a 1A current limit through
the external connector. If the phone draws
more than 0.5A, check all the regulators sig-
nals for short to ground
• Check for the power B+ at C3803 or C3804,
if no B+ present replace U3800
• Place a zero ohm resistor at R3000
• Check the regulated output voltages
•.if the voltages on the regulators are not correct
Table 7:
Linear Regula- Nomi-
tor nal Volt-
age
VREG_MSMP 2.83V
VREG_MSMC 2.86V
VREG_MSMA 2.65V
VREG_IF 2.90V
VREG_TCXO 2.75V
reflow or replace U3000
• Check the RTC clock Y3000: check the
clock for 32.768 Khz signal if not present
check C3000,C3001, C3002 and C3011, then
replace Y3000
• Check the 19.2 Mhz clock signal at C3012 if
Remember to remove R3000 – zero ohm resistor
after the trouble shooting process.

Internal Charger Test Debugging

Phone must be in Phone T mode to analyze
charger.
In DMSS mode, the default state of the
charger is off unless a valid charger (fast or
mid rate) and battery (EPROM and Ther-
mistor present) are detected by software.
Charging circuitry (except for PM1000) is next
to battery contact block and not under any
shields.
When charger is disabled, the EXT_B+ current
should be ~150mA +/- 50mA. Otherwise battery
charge test current limits will be exceeded. This
failure may not be caused by the charger circuit.
When charger is enabled (using set DVT Option
command) with 3.6V battery connected,
EXT_B+ current should be at 1A for high current
test, and ~370 for mid rate current test. If not,
verify that EXT_B+ is >4.4V at CEBUS connec-
tor and battery voltage is 3.6V at the battery con-
tact block.
Location to
When charger is enabled, battery charge current
check
will be 1A – EXT_B+_Current for high rate, and
370mA – EXT_B+_Current for mid rate current
C3200
settings.
C3150
When charger is enabled, voltage on R3800
C3100
(side connected to U3800) should be at 1.5V.
This voltage is proportional to the EXT_B+ cur-
C3250
rent and is calculated by (EXT_B+_CURRENT/
C3450
CURRENT_LIMIT) * 1.5 where current limit is
either 1A or 0.370A.
61
Product Support Tools
not present check L650 and replace Y650
3/1/02