Philips PM 5509 Bedienungsanleitung Seite 21

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2.@ Animpression of the horizontal and vertical linearity of the deflection can be obtained 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 intensity 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 service notes of the relevant receiver.
D. PATTERN 4
"Dots"
1. a Check and, if necessary, re-adjust the static convergence in the centre of the screen at low ambient
brightness. This should be done according to the instructions of the manufacturer of the receiver.
Fig. 14 shows a detail of an incorrectly converged picture.
E. PATTERN 5
| "Definition lines and a 8-step grey scale combined"
Definition lines (see Fig. 16)
1.2 The top two-thirds of this pattern contains 8 sets of definition lines ranging from 0.6 MHz to 5 MHz.
The definition lines are for measuring the bandwidth of a video- or luminance amplifier of a TV/C.T.V.
This part of the pattern can also be used for checking the resolution of the black and white part of a
video recorder. The resolution must be adjusted to an optimum because the bandwidth for black and
white signals is already limited. A difficulty for the adjustment of a V.C.R. is that the resolution, and
hence the bandwidth, must be sufficient and without intermodulation with the colour signal.
Grey scale (bottom third) See Fig. 16
This greyscale signal is a linear staircase signal.
It has not been derived from the colour bar signal by removing its chroma-information.
i
J 1.@ Check the proper functioning and the range of the brightness- and contrast controls of the receiver.
In some receivers the black level is kept constant and is not effected by operation of the contrast
while each of the 6 steps in between should show an equal increase of grey from left (black) to the
right (white)
Check the proper greyscale setting of the colour receiver. The various greybars should not contain
any colour (if the greyscale setting is not correct, the ratio between the beam current and the contr ol-
grid curves of the three guns of the picture tube is not constant; re-adjust according to the
instructions in the Service Notes of the relevant receiver).
Sy ere U n e e s e
N
a
3.@ The following check with this pattern requires the aid of the oscilloscope.
Check the non-linearity of the video amplifier of the receiver with the contrast control at maximum.
Check that each step of this greyscale signa! at the output of the video amplifier is equal. This can
easily be measured by comparing it on the dual trace oscilloscope PHILIPS PM 3110 with the sigra§ on
socket VIDEO.
4.0 Checking the linearity of the video amplifier and the FM-demodulator of a V.C.R.
F. PATTERN 6
"Red"
This pattern has a 50 % saturated red signal (see Fig. 17)
1.™
Set the brightness and saturation controls of the receiver so that a red pattern with a good intensiy
appears.
|
2. Check the purity of red (this pattern offers the adventage that the green and blue guns need not
switched off). Larger convergence errors may have an effect on this check.