Pioneer RS-A9/EW, Service Manual

Page: 90 / 128

RS-A7/EW
90
1 2 3 4
1 2 3 4
C
D
F
A
B
E
6.2 AUDIO UNIT ADJUSTMENT
(The measuring points for adjusting master clock)
TP3001 or its equivalent land and TP3002 or its equivalent GND
(Waveform Confirmation for Adjustment)
Waveform confirmation is required since the waveform may be deformed according to the
type of probe to be used when adjusting master clock.
The waveform is basically a rectangular wave of 0 --- 3.3V (24.576MHz).
Sensing pin land of AL2 : its equivalent land and GND
Sensing pin land of AR2 : its equivalent land and GND
Sensing pin land of BL2 : its equivalent land and GND
Sensing pin land of BR2 : its equivalent land and GND
(Adjustment Requirements)
Operate the product in the following requirements and make adjustment within 2 or 3 minutes from the start of
such operation.
(Measuring instruments to be used)
For adjusting offset voltage: Voltage measuring device such as a multi-meter
For adjusting master clock: Frequency counter or high-frequency probe
* For adjusting each of RS- A7, use RS- A9.
The items for adjusting audio unit are:
1
Offset voltage
2 Master clock
The adjustment for service should be served in the product condition, instead of in the unit condition.
(Otherwise, it would require jigs.)
Both adjustments are capable by removing the bottom plate of product, the sealed case of Control Assy and
black panel (IN/OUT-signal printed side) to expose the face A of audio unit.
Adjustment is done by using the following half-fixed resistance and the trimmer capacitor:
For adjusting offset voltage --- VR2241, VR2271, VR2341, VR2371
For adjusting master clock --- TC3001
Offset Voltage
Item No.
Set volume value of Main Unit to - 72dB and
reproduce CD without recording. *1
Requirements
0 Below 10mV
Master clock
1
2 Set volume value of Main Unit to - 72dB and
reproduce CD without recording. *1
Rated Value
24.576MHz 20Hz
*1 : 23 tracks of test disc(YEDS-7)