Dynamic Gamma; High Voltage Frequency Adjustment; Video Level Alignment - Philips PTV500 series Service Manual

Dynamic Gamma (this adjustment requires the use of equip-
ment not normally carried into the home)
1 .Apply a Crosshatch pattern utilizing 1001RE (100% white) to
the antenna terminals (Very important step, anything less
than 1001RE will not work correctly).
2. Tune set to this signal and adjust the Customer Brightness
and Picture Controls to maximum.
3. Set the Gamma Adjust Control (R603) to its full counter-
clockwise (CCW) position.
4. Display the main customer menu on the screen. Note the
blue bleeding at the blanked boarder area on the left-hand
edge of the menu.
5. Rotate the Gamma Control (R603) slowly clockwise (CW) to
just eliminate the blue bleeding in to the menu area.
High Voltage Frequency Adjustment (this adjustment requires
the use of equipment not normally carried into the home)
1. Turn the set Off and disconnect power supplied to the chas-
sis.
2. Undo cable restraints and fold the chassis down (in order to
gain access to the copper side of the module).
3. Locate the copper pad for TP67 and solder a short piece of
wire onto it.
4. Connect a jumper lead to this test point and connect the
other end to ground.
5. Connect a Frequency Counter to Test Point TP38.
6. Turn On the set and adjust R902 to obtain a reading of
15.734kHz on the counter.
7. Disconnect test equipment and remove the short from TP67.
Note: Some Frequency Counters may be too sensitive at one
attenuation level and not sensitive enough at the other level. In
this case, an oscilloscope may be used. Adjust R902 to obtain
a 63.5uSec delay from the leading edge of the first main vertical
pulse to the leading edge of the second main vertical pulse.
Video Level Alignment (this adjustment requires the use of
equipment not normally carried into the home)
1. Apply an NTSC Color Bar Pattern Signal to the antenna ter-
minals.
2. Tune the receiver to the applied signal in step 1.
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