Pioneer tuning fork Service Manual page 19

®. Color Bars
Color bar pattern is composed of color bars in order of
luminance.
Upper pattern: From left — White, yellow, cyan,
Lower pattern: From left — Q, - I , * white and black
This signal is for chrominance (chroma) circuit adjustment.
•Refer to p-13.
Example
V C R Adjusting luminance and chroma levels
Adjusting A u t o Colour Control (ACC)
Balancing chroma level
Setting burst gate — phase and am­
plitude
Measuring moire
TV receiver Adjusting chroma circuit
Adjusting A C C circuit
The white level of upper color bars is 7 5 % in amplitude.
W h e n 100% white is required, use the white signal of the
lower pattern.
®. IQW Off
Upper bars can be displayed on full screen with this switch
depressed. When 100% white is required, turn the IQW on.
*IQ signal: In NTSC system, the color information is
broadcast on I and Q signals. These signals are on the
orange-cyan and green-magenta axes respectively for ef­
fective broadcasting. The axes have a 90° phase difference
each other. P A L system uses U and V axes. Ref. P I 3 .
®. Chroma Off
The color bars can be m a d e colorless by depressing this
switch. This gray pattern is used to adjust the linearity of
picture amplifier circuit, white balance, etc.
green, magenta, red, blue
and black
White Yellow Cyan
Green Magenta
(75%)
Q -S White (100%)
Fig 2 Color Bar Pattern
Yellow
Cyan Green
White
Color
burst
- I
Q
Weighted: The amplitude is reduced to meet the sensitivity of
our eyes and t o avoid oversaturation.
Fig. 3 Color Bar Signal with 7 . 5 % Setup
Upper -
pattern
H Sync
Fig. 4 Luminance Signal of Color Bar Pattern
Red Blue
Black
Black
Magenta
Red Blue
Black
- Lower pattern
Black level
Pedestal level
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