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Tune to a TV station having teletext signals; the signal must be
sufficiently strong (>lmV) and free of reflections and
interferences of a certain intensity.
Select a teletext page with continuous data renewal and damp
signal until a few errors appear.
Adjust L4T so as to make character errors disappear or for the
least number of them.
Use a teletext generator having a pseudo-random sequence.
Connect the oscilloscope's probe to pin 18 of SAA 5030 (CLOCK
output) and synchronize it externally with clock signal of
teletext generator.
Adjust L4T for a stable clock signal.
Final check.
page III; check for completeness and exactness of the
Select
heading line and of page characters.
Check functions of TELETEXT transmitter.
Testing of teletext p.c.b.
1) Check supplies:
Test transcoder and transmitter
Depress in TV mode some programme selecting controls and check
exactness on display.
Always in TV mode visually check efficiency of analogical controls
(brightness, colour, volume muting, normal setting).
Check in text mode efficiency of all controls.
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