Fostex CR200 Service Manual page 18

CR200
4.2.2 Coarse Focus Offset Adjustment
• Objective
• Symptom when out of adjustment
• Measurement instrument connections Osciloscope to CN204, Pin-1 (RF) (SERVO UCOM BOARDassy)
• Disc
• Player state
• Adjustment location
[ Procedures ]
(1) Press the FINALIZE key and the PLAY key in the order to close the focus servo and then the spindle servo.
(2) Adjust VR105 (FE. OFS) so that the amplitude of waveform at CN204 (TP201), Pin-1 (RF) is maximum.
NOTE: The oscilloscope displays a moving image, not a ÒSTILLÓ image as shown below. In order to verify that the focus
servo is on, tap on the machine gently and listen to the sound indicating the servo operation.
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To coarse adjust the DC offset voltage of the focus servo circuit to perform the
tracking and slider adjustments correctly.
The unit does not focus in, sound is cracking and the RF signal is dirty.
GND probe can be connected to CN204, Pin-4 (AGND).
[ Settings ]: 20 mV/div., 2 mS/div., DC mode
TCD-785
Test mode, focus and spindle servos: closed, tracking servo: open
VR105 (FE. OFS) (HEAD BOARD assy)
Out of adjustment
Optimum adjustment
(Waveform amplitude is at maximum.)
Fig. 10