SECTION IV CALIBRATION PROCESS

SECTION IV.

CALIBRATION PROCESS

minimum chroma (signal level) on 0.5-volt pedestal of

waveform.

NOTE

Unless otherwise specified, verify the

(14) Connect oscilloscope probe to TP4539 (fig.

results of each test and, whenever the test

3). Adjust L4460 and L4456 (fig. 3) for optimum peak

requirement is not met, take corrective

response of the demodulated VIR signal and chroma.

action before continuing with the

(15) Adjust video signal source (A6) for 10

calibration.

percent APL (average picture level) flat field output. If

APL, as indicated on oscilloscope is not zero, perform

8. Timing Circuits. a. Performance Check.

b(8) below.

(16) Adjust TI PEDESTAL DELAY control for

(1) Connect the oscilloscope (A4) to TI TP3308

minimum aberration on waveform approximately 62

(fig. 3), using probe (B2).

microseconds from leading edge of horizontal sync

(2) If dc level indicated on oscilloscope exceeds

pulse.

+20 millivolts, perform b(l) below.

(17) Adjust TI PEDESTAL START control for

(3) Connect oscilloscope probe to TP3250 (fig.

minimum aberration on waveform approximately 11

3).

microseconds from leading edge of horizontal sync

If width of displayed pulse is not 4 +0.2 microseconds,

pulse.

perform b(2) below.

(18) Adjust video signal source for 0 APL flat

(4) Turn TI PEDESTAL DELAY and START

field output. If APL, as indicated on oscilloscope, is not

controls to midrange.

zero, perform b(8) below.

(5) Connect oscilloscope probe to TP3385 (fig.

3).If width of displayed pulse is not 11 +1 microseconds,

b. Adjustments (1) Adjust L3400 (fig. 3) for oscilloscope

perform b(3) below.

indication of zero volt dc (R).

(6) Connect oscilloscope probe to P3912-3 (fig.

3) (7) Adjust oscilloscope to display horizontal sync pulse

(2) Adjust R3624 (fig. 3) for 4-microsecond

and position leading edge of pulse at second vertical

pulse width (R).

graticule line.

(3) Adjust R3156 (fig. 3) for 11-microsecond

(8) Connect oscilloscope probe to TP3876 (fig.

pulse width (R).

3).If trailing edge of displayed pulse is not 8.5 +0.5

(4) Adjust R3282 (fig. 3) until trailing edge of

microseconds from second vertical graticule line,

displayed pulse is 8 microseconds from second vertical

perform b(4) below.

graticule line (R).

(9) Repeat (6) and (7) above.

(5) Adjust R3534 (fig. 3) until leading edge of

(10) Connect oscilloscope probe to TP4141 (fig.

displayed pulse is 17 microseconds from second vertical

3). If leading edge of displayed pulse is not 17 +0.5

graticule line (R).

microseconds from second vertical graticule, perform

(6) Adjust R3438 (fig. 3) until trailing edge of

b(5) below; if trailing edge is not 32 +0.5 microseconds

displayed pulse is 32 microseconds from second vertical

from second vertical graticule, perform b(6) below.

graticule line (R).

(11) Connect oscilloscope probe to TP4139 (fig.

(7) Adjust R3540 (fig. 3) until trailing edge of

3). f trailing edge of displayed pulse is not 46 +1

displayed pulse is 46 microseconds from second vertical

microseconds from second vertical graticule line,

graticule line (R).

perform b(7) below.

(8) Adjust R5404 (fig. 4) for zero APL indication

(12) Connect oscilloscope probe to TP4505 (fig.

on oscilloscope (R).

3).

(13) Adjust oscilloscope to display VIR (vertical

interval reference) signal. Adjust L4378 (fig. 3) for