JVC RC-X3 - Page 18

RC-X3 B/E/G
(3) Tracking gain adjustment
Hi Adjustment tools: 2-needle vacuum tube voltmeter, oscillator, measuring jig, normal disc
1) There is a pattern cut round between TP3 (IC501 0 terminal) and TP10 R613. Remove the solder and connect the
measuring jig to both ends. Cut Round
2) Set the oscillator’s output at 1.1 kHz, 180 mVRMS. sae
3) Playback a normal disc. [tPs@ Lp 3
4) Adjust VR505 so that it matches the output level of the measuring jig. R613
If proper adjustment cannot be made (with the jig or measuring instrument, etc.), center VR505 mechanically.
CD pickup maintenance
(1) Check the service life of the laser diode. Pickup replacement procedure.
a. Insert the disc and turn on the power.
b. Press the PLAY button (S601) to playback a track. Set to unit mode, and check if the power is not on.
c. Use an oscilloscope to measure the RF output. If it is
0.6 VP-P or lower, wipe the objective lens with a cotton
swab. Do the measurement again. If the RF output is Remove the CD mechanism from the CD board.
0.6 VP-P or lower, the laser diode needs to be replaced. =
Replace tt wen Replacing she pienie: Loosen the screws securing the pickup holder and shaft,
d. If the RF output is higher than the above values, measure and remove the old pickup
the voltage of both ends of R507 (10 2) mounted on the L_ :
board. If it is 1.2 V or higher, replace the pickup. |
* To obtain a diagnosis, do steps c and d. Remove the solder from the pickup board's laser protec-
tion short land.
(2) Semi-fixed resistor on the APC board ae
The semi-fixed resistor on the APC board mounted on
the pickup is for adjusting the laser power. This adjust- Mount a new pickup, and connect the connector secure-
ment is done in pairs according to the optical block ly. Then mount the CD mechanism on the CD board.
characteristics. Therefore, do not touch the semi-fixed |
resistor.
Turn on the power without inserting a disc. When the
laser emits, check if the lens is able to move up and
down.
(Caution: Do not look at the laser directly.)
ae
Do VCO free run adjustment.
If the laser power is low, it is due to the laser diode.
Pickup replacement will be necessary. If a semi-fixed
resistor of a normal pickup is turned, the pickup may
be damaged due to excessive voltage.
(3) Grading adjustment
Grading adjustment is done part-by-part to obtain the
best adjustment. Ey
If the adjustment is off, playback will be impossible Preset VR501 and VR505, which are for tracking adjust-
because the laser beam will go to incorrect tracks. ment, to the center position.
Playback the disc, and check if the disc spins properly.
Sn
Do tracking offset adjustment.
Do tracking gain adjustment.
Are PLAY
and SKIP operations\_NO
working properly?
Refer to the repair guide.
YES
Replacement is complete
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