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8. Offset adjustment in drop-out
Shee
. After the above-mentioned adjustment, remove the short lead in step 3.
. Maximize VR501 by turning it fully clockwise.
. Place the disc on turntable and press Play button. (Play mode).
. In play mode, connect TJ501 on 01 P.C.B. to GND.
. In the same
oscilloscope mode as in step 2, adjust VR501
so that the oscilloscope wave is formed shown below.
. Connect the oscilloscope to the points specified below.
TJ101 (03 P.C.B.)
TJ103 (03 P.C.B.)
TJ401 (01 P.C.B.)
Oscilloscope setting:
VOLT
1V (both channel), SWEEP 0.5ms, Input AC,
Trigger EXT. NORM
ee
. Play band 13 (0.5 mm black spot) of the test disc.
. Watching
the waveform
of CH1
of.the oscilloscope,
adjust VR103
so that the waveform amplitude near the
trigger point is minimized.
If not minimized, adjust so
:
EXT].
that the waveform top and bottom are nearly symmetrical.
-
. Watching the waveform of CH2 of the oscilloscope, adjust VR106 so that the waveform amplitude near the
trigger point is minimized.
If not minimized adjust so that the waveform top and bottom are nearly
symmetrical.
. Best eye adjustment
.
Match the negative edges of both waveforms.
. Connect
CH1
of oscilloscope to TJ402 on main P.C.B..
Oscilloscope setting:
VOLT 1V, SWEEP 0.5ys, tnput AC
:
> Insert dise and place unit in play mode,
*
O
——,
pearenas
11. Check of play operation after adjustment
. Adjust VR102 so that the eye pattern of RF signal is
- |
é
ee
widest open.
:
ee
Ge ey
em ae ak
Check of skip search
,
i e
a l
oP
A y
1. Play an ordinary disc.
2. Press the skip button and check to see that skip search is given.
(Forward and reverse)
Check of manual search
1. Play an ordinary disc
2. Press the manual search button and check to see that smooth manual search can be done at low and high
;
speeds.
(Forward and reverse)
10. PLL adjustment
Check for defects
1. Play the band 12 of test disc, and check to see that there is no sound skip or noise.
(Black spot)
2. Play the band 14 of test disc, and check to see that there is no sound skip or noise.
(Fingle print)
. Place the unit in the Eject mode. (tray open)
. Connect CH1 and CH2 of the oscilloscope to test points TJ701 "'FCLK" and TJ702 ""CLDCK" on 01 P.C.B.
Oscilloscope setting:
,
VOLT 2V (both channels), SWEEP 20us, Input AC, Trigger CH1
+ CH2 (NORM) ©
slope, Mode ALT.
. Connect 1C301 pin 13 on 01 P.C.B. to GND.
. Adjust L301 so that the timing waveform appears as shown below.
Match the centers of both waveforms.
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