Backlight - Nokia NHL-2NA Series Troubleshooting Instructions

NHL-2NA

Backlight

There are basically two kind of problems with the keyboard backlight. The backlight may
be dim or there there may be no backlight at all. The following flowchart describes how
these two problems can be detected and solved.
Repair, and change if
necessary, connectors
and Flex cable.
no
Check
Connectors and flex
cable that their
contacts are ok
and retest,
OK?
yes
yes Change UEM
and retest,
OK?
no
Beyond of
economical repair
Problem solved
Page 2
Backlight
malfunction
Check and measure
that R013 and R014 are
on their places and
parallel resistance is
~21.4 Ω.
OK?
yes
Measure that
the voltage over N320
pin 8 is 4.1V only when
backlight is activated.
OK?
no
Measure from J021
no that voltage is ~Vbat
when the keyboard
backlight is turned on.
OK?
yes
Change N320 to a new
one and retest.
yes Does backlight
work?
¤Nokia Corporation
CCS Technical Documentation
no Change resistors
and retest
Check LEDs
yes that they are
properly assembled
(anode / cathode).
OK?
no
Reassemble them
and retest.
Beyond of
economical repair
no Change
the whole grip-PWB
and retest
yes
Change the
no whole grip-PWB
and retest,
OK?
yes
Problem solved
Issue 1 07/02