Philips PM 5508 Operating Manual page 34

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2. •
Check the focussing of the picture (adjustment of the d.c. level on
the third grid of the picture tube). At the same time, an impression
can be obtained of the horizontal and vertical linearity of the deflec-
tion, as the horizontal and vertical white lines should form squares.
Moreover, it can also be determined if the receiver's amplitude
response is correct. The vertical white lines have a width of 200 ns.
If these lines appear "unsharp" and show considerably less inten-
sity than the horizontal ones, the amplitude response of the receiver
is insufficient. If the vertical white lines appear "double", the circuits
of the receiver cause ringing.
3. •
Check the pin-cushion correction of the receiver. This correction
requires readjustment if the white lines, horizontal as well as vertical,
do not seem to be straight and parallel at normal viewing distance.
See the Services Notes of the relevant receiver.