Trouble Shooting Guide, Advanced
4/00021-3/FEA 209 544/25 C
Ericsson Mobile Communications AB
10(78)
3 EEPROM
3.1 Write to EEPROM
Large amount of data is stored in the RAM memory of the phone during the radio calibration
in EFRA.
This information is stored permanently in a 32 kB*8 large EEPROM after interpolation.
This is done after calibration, write Local Table to EEPROM.
ThedatatransferisdoneseriallyatanI
2
C-bus, Inter IC. The I
2
C-bus consists off two lines,
I
2
CDAT for data and I
2
CCLK for clocking.
The figure below shows a schematic over the data transfer.
DISPLAY
I
2
CCLK
I
2
CDAT
N700
D 600
D 602
EEPROM
Fig.3.1
3.2 How to find the fault
There is a possibility, in the trouble shooting part of EFRA, to test the communication and a
limited part of the function in the self-test.
The functionality test that is done is the processor writing and reading at a few addresses.
If the self-test shows ”Check EEPROM Failed”, the phone is faulty, but the self-test does not
display all faults, so there is a possibility for the self test not to detect the fault.
Open the phone and check for liquid damage.
No further action should be taken for a liquid damaged unit, send it on according to the
local company directives.
Check R801, R802.
Make sure there is not a short circuit against ground at I
2
CCLK or I
2
CDAT.
Power up the board and check VDIG.
The fault is usually due to D602.
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