Nokia 301 Service Manual page 132

RM-839; RM-840; RM-841
Camera Module Troubleshooting
move onto the image sensor active surface, for example, when the phone is dropped. Thus it is also possible
that the problem will disappear before the phone is brought to service. The camera should be replaced if the
problem is present when the service technician analyses the phone.
If a dust particle is lying on the infrared filter surface on either side, they are hard to locate because they are
out of focus, and appear in the image as large, grayish and fading-edge 'blobs'. Sometimes they are invisible
to the eye, and thus the user probably does not notice them at all. However, it is possible that a larger particle
disturbs the user, causing need for service.
Figure 36 Effects of dust on optical path
If large dust particles get trapped on top of the lens surface in the cavity between camera window and lens,
they will cause image blurring and poor contrast. The dust gasket between the window and lens should
prevent any particles from getting into the cavity after the manufacturing phase. Dust in this position should
be blown away by using compressed air.
Unauthorized disassembling of the product can also be the root of the problem. However, in most cases it
should be possible to remove the particle(s) by using clean compressed air. Never wipe the lens surface before
trying compressed air; the possibility of damaging the lens is substantial. Always check the image sharpness
after removing dust.
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