Pioneer CDX-M12 Service Manual page 19

9 Focus Servo Loop Gain Adjustment-1
* Focus Servo Loop Gain Adjustment-1 may be per-
formed in Focus Servo Loop Gain Adjustment-2. ~
.© Purpose: . 3 :
To adjust the focus servo loop gain to an optimum val-
ue. aa
* Maladjustment symptoms:
Poor playability, reduced resistance to vibration, fo-
cus closure fails readily.
* Measuring equipment / jigs:
Oscillator, gain adjustment filter (GGF-065),
oscilloscope, dual meter milli-voltmeter,
volume adjustment driver
¢ Measuring point:
FEX, FEY
* Test disc and setting:
SONY TYPE 4 (or ABEX TCD-782) Normal mode
* Adjustment position:
VR355
Oscillator Oscilloscope
1mS / div.
50mV / div.
AC mode
Dual meter
milli-voltmeter
Gain Adj.
ally z
-065 ve
foc —
Note : Leave the negative
side of the other oscilloscope
channel open.
Connect the negative millivoltmeter
lead to REFOUT, and do not connect
REFOUT to the power supply ground.
MAIN UNIT
Adjustment Procedure
1. After checking that the power is OFF, connect the
gain adjustment filter and measuring equipment as
shown in the above diagram.
. Play tune TNO 12 in normal mode.(ABEX TCD-782
:TNO 19)
. Set the oscillator to 1kHz,and observe the FEX/FEY
output in the oscilloscope. Adjust the oscillator out-
put to obtain a FEX/FEY output of 100mVp-p.
. Adjust VR355 to obtain a milli-voltmeter difference of
0+0.5dB.
CoxX-Mi2
10 Focus Servo Loop Gain Adjustment-2
¢ Purpose:
To adjust the focus servo loop gain to an optimum
value.
¢ Maladjustment symptoms:
Poor playabillity, reduced resistance to vibration, fo-
cus closure fails readily.
¢ Measuring equipment / jigs:
Oscillator, gain adjustment filter, oscilloscope
¢ Measuring point:
FEX, FEY
* Test disc and setting
SONY TYPE 4 (or ABEX TCD-782) Normal mode
« Adjustment position:
VR355
Oscilloscope
MAIN UNIT X-¥ mode
Adjustment Procedure
1. After checking that the power is OFF, connect the
gain adjustment filter and measuring equipment as
shown in the above diagram.
. Play tuneTNO 12 in normal mode.(ABEX TCD-782:TNO
19)
. Set the oscillator at 1kHz and adjust the output of
the oscillator to 2Vp-p.
. Adjust VR355 to make the Lissajou's figure of wave-
form symmetrical about X and Y axes respectively.
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