RCA SelectaVision VideoDisc SFT 100 Service Data page 81

СЕО-1 Аддепдит-2
ELECTRICAL ADJUSTMENTS
(continued)
R.F. Output Channel Oscillator Adjust
і;
5.
With power applied to player, place Channel Switch, $3501. in
Channel 3 position (Figs. 4-9 & 5-2). Connect player to TV ог
75 ohm toad.
Connect marker generator (R. F. input) to TP 3501 and adjust
for 61.25 MHz output.
Adjust L3501 for zero beat.
Place Channel Switch, 53501, in Channel 4 position.
Connect marker generator (R. F. input) to TP 3502 and adjust
for 67.25 MHz output.
Adjust 13502 for zero beat.
TRAP ADJUST —
7.
9.
10.
11.
Turn player power off and connect marker generator output to
TP 3501 marker generator set at 56.75 MHz (Fig. 5-2).
Connect quadrupler detector (Fig. 4-10) to J3502. Connect
oscilloscope (or О.С. Voltmeter) to quadrupler detector and
set oscilloscope on DC @ 10 mV/Div.
10K 1460 100pf 330pf
В212124:1
Fig. 4-10. — Quadrupler Detector
Adjust 13504 (Fig. 4-9) for null (minimum deflection).
Connect marker generator output to TP 3502, marker
generator set at 62.75 MHz.
Adjust 1.3503 (Fig. 4-9) for null (minimum deflection).
BANDPASS ADJUST —
12,
13.
14.
15.
16.
Connect quadrupler detector and oscilloscope as in step 8.
Connect marker generator to junction of R3514 and R3516
(Fig. 5-2).
Set marker generator to 65.75 MHz and adjust 1.3505 (Fig.
4-9) for peak output (maximum deflection).
Set marker generator to 61.25 MHz and adjust 1.3506 (Fig.
4-9) for peak output (maximum deflection).
Turn player power on and check operation. Repeat steps 13
thru 16 if necessary.
4.5 MHz Osc. Adjust
1.
2.
3.
Connect player to TV, player ín load mode.
Monitor a suitable point in TV IF to pick-up 4.5 MHz sound
carrier with a frequency counter.
Adjust L3509 (Fig. 4-9) for 4.5 MHz +1 kHz.
3.58 MHz Reference Oscillator Adjust
1.
Connect player to TV, insert Test disc and place player in play
mode.
2. Use full field color bar signal (Segment D) and monitor а
Suitable point in the TV 3.58 MHz oscillator circuit with а іге-
quency counter.
3. Adjust C3406 (Fig. 4-9) for 3.579545 +10Hz.
Alternate Method —
1. Connect frequency counter via X10 probe to TP 3413 (Fig.
5-2).
2. With player in load mode adjust C3406 (Fig. 4-9) for 3.579485
MHz.
(This method allows approximately 60 Hz variance as compensa-
tion for loading effect of the frequency counter).
Note: Typical capacity of X10 probe and counter is approx-
imately 20-25pi. A X1 probe (typical capacity of approx-
imately 100pf) may be used with a 33pf capacitor is placed
in series with probe. This will place a load on the VCO of
approximately 25рі.
Video Modulation Depth Adjust
1. Connect player to TV.
2. Use Test disc 120 IRE White field signal (Segment G).
3. Adjust R3402 (Fig. 4-9) Clockwise till a buzz is heard in TV
audio, then turn R3402 counterclockwise to just eliminate the
buzz.
Audio Level Adjust
1. Use Test disc signal with 480 Hz, 100% audio modulation
(Segment Е}.
2. Connect oscilloscope to TP 3601 (Fig. 5-2).
3. Adjust R3609 (Fig. 4-9) for 1.2V р-р output.
VCXO Adjustment
3.58 MHz Reference Oscillator Adjustment should be checked,
and if necessary performed. prior to making this adjustment.
Step A. Determining VCXO Frequency Limits
1. Connect DVM from TP 3406 to ground (Fig. 5-2).
2. Use Test Disc (Stock No. 149235) signal Segment І.
3. Connect 1.5 megohm resistor from TP 3412 to +15V source.
4. With player in play mode, record voltage measured on DVM
as V1. (example V1 = 8.66V)
5. Remove 1.5 megohm resistor end from +15\ source and con-
nect it to ground.
6. Record voltage measured on DVM as V2. (example: V2 —
7.090). Remove grounded end of 1.5 megohm resistor. leave
one end connected to TP 3412.
7. Using the formula AF = 3/2 (V1-V2-.177) kHz, calculate AF.
(The result should be between 1.90 and 2.52 kHz.)
EXAMPLE:
AF = 3/2 (8.66V - 7.09V - 177) kHz
AF = 3/2 (1.393) kHz
AF = 1.5 x 1,393 kHz
AF = 2.09 kHz