RCA SelectaVision VideoDisc SFT 100 Service Data page 24

CED-1
ELECTRICAL ADJUSTMENTS
(continued)
Servo Position Adjust (R520)
1. Short TP 510 (arm output) to TP 521 (Ground)
2. Connect DVM from TP 513 to TP 514 (Fig. 4-1).
3. Adjust R520 for less than 5 millivolts.
4, Remove short from TP 510 to ground.
SERVO
POSITION — resi
ADJUST 510 ТР521
| ЙТР 514 ТР 513
Fig. 4-1. — Servo Position Adjust
МАС Adjust (R713 and C710)
Use test disc Stock No. 149235 on Band L (20 IRE Gray Field with
480 Hz, 100% modulation on audio carrier).
1. Place player in "pause" mode.
Connect DC voltmeter to test stake PW 700-CV (Fig. 4-2).
Adjust R713 to produce 9.5V D.C. reading.
Connect D.C. voltmeter to test stake ТР 701.
Short wiper of R713 to ground with cliplead.
ә m» won
Place player in "play" mode and check that Band L is being
played.
~ Adjust 2710 for minimum voltage at TP 701.
Remove cliplead.
R713 C710
=
PW 700-CV
Fig. 4-2. — NLAC Adjust
Arm Servo Balance Adjust (R917)
Player should be in normal play mode with a standard disc at ap-
proximately 30 minutes play time (30 showing on readout indica-
tor). when making this adjustment.
1. Connect oscilloscope, to TP 532 (scope set to .1т5/0іу. 2V p-
p) Fig. 4-3.
2. Alternately press Visual Search "FWD" and Visual Search
"REV" buttons for several seconds.
ARM |
SERVO —
BALANCE ^
ADJUST
R917
Fig. 4-3. — Servo Balance Adjust
3. Adjust arm servo balance control (R917 on pick-up arm as-
sembly) until width of kick pulse is approximately the same in
both Visual Search "FWD" and "REV" modes (approximately
450 to 750 uS width negative pulse). (See Fig. 4-4)
Note: Misadjustment of arm servo balance adjustment (R917) ог
Servo Position Adjust (R520) could result in loss of Visuai
Search in one direction.
Fig. 4-4. — Servo Balance Adjust Pulse
Video Demodulator VCO Adjust
1. Disconnect interconnect plug P3002 (Fig. 5-2).
2. Short the two pins of J3002 together.
3. Connect Frequency Counter via X10 probe (see note) to TP
3202,
4. Adjust C3215 for 5.25 MHz +50 kHz.
5. Remove short from the two pins of J3002 and reconnect
P3002.
Note: Typical capacity of X10 probe and counter is approx-
imately 20-25pf. A X1 probe (typical capacity of approx-
imately 100pf) may be used with а 33pf capacitor is placed
in series with probe. This will place a load on the VCO of
approximately 25pf.
Audio Demodulator VCO Adjust
1. Disconnect interconnect plug P3002 (Fig. 5-2).
2. Short the two pins of J3002 together.
3. Connect frequency counter via X10 probe (see note) to TP
3602.
4. Adjust C3607 for 716 kHz +2 kHz.
5. Remove short from the two pins of J3002 and reconnect
P3002.
Note: Typical capacity of X10 probe and counter is approx-
imately 20-25pf. A X1 probe (typical capacity of approx-
imately 100pf) may be used with a 33pf capacitor is piaced
in series with probe. This will place a toad on the VCO of
approximately 25pf.