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The PWM signals look like in the Fig. 23.3. below.
Notice that the PWM signals for a phone with signal program and a phone with test program
does not look the same.
A fault in the PWM signals is usually due to incorrect soldering at D600, a short circuit in the
capacitors between the PWM generators and the diodes and sometimes on just a faulty D600.
If the VLCD voltage is within the limits in Table.19, but VLCD-meas is not within the limits,
the fault can be due to VDIG, a short circuit in C824 or the voltage divider R807 or R808.
If VLCD-meas and VLCD, is within the limits, the fault can be due to one of the DC voltage or
digital signals at the pads of the display (H623) is missing.
Table.23.3. show the voltage at the pads of the display.
Pin 1
Pin 2
Pin 3
Pin 4
Pin 5
Pin 6
Pin 7
If I2C-DATA and/or I2C-CLOCK are missing, the fault can be due to R614, R615, R619 or
R620.
The fault can also be due to incorrect soldering at D600 pin 3,4 or a fault in D600.
Sometimes the fault can be due to the feed voltage VDIG.
If VLCD is incorrect, go back to the beginning of this section.
If VLCD is missing, the fault can be due to incorrect soldering at D600 pin 45; D600, C615,
C674 or an incorrect feed voltage VDIG.
Measure the resistance between GND at H623 and the negative batter connection.
If the resistance is larger than 1 ohm, there might be a foil damage.
4/00021-3/FEA 209 544/18 B
Fig. 23.3
Signals and levels at
H623
RESETO
I2C-CLOCK
GND
VDLCD
VLCD
I2C-DATA
Not in use
Table.23.3
Trouble Shooting Guide, Advanced
~3.2 V
~3.2 V
zero V
~3.2 V
~-2.8 V
~3.2 V
zero V
104(121)
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