Nokia NHL-4 7210 Service Manual page 170

NHL-4/4U
Troubleshooting Instructions
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Start
Is the power key
working?
Yes
Is the volume
UP key working?
Yes
Is the volume
Down key
working?
Yes
Continue
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Measure voltage
No
from S302. Is it
HIGH?
Yes
Measure voltage
from S302 when
pressed. Is it
HIGH?
No
Phone is
jammed
Measure ROW0
No
line from S300.
Is it ~1.8V?
Yes
Measure COL0
from S300 when
pressed. Is there
50us pulse?
Measure ROW1
No
line from S301.
Is it ~1.8V?
Yes
Measure COL0
from S301 when
pressed. Is there
50us pulse?
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Check
R306,C310,S30
No
2 and line. If OK,
change UEM
Check S302. Is
Yes
it OK?
No
Check S300 and line.
If OK, change Z300.If
No
still FAIL, change
UPP
Check S300 and
COL0 line. If OK,
No
change Z300.If still
FAIL, change UPP
Yes
Change UPP
Check S301 and line.
If OK, change Z300.If
No
still FAIL, change
UPP
Check S301 and
COL0 line. If OK,
No
change Z300.If still
FAIL, change UPP
Yes
Change UPP
Phone is
Yes
dead
Change S302
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