Sharp SD-EX200 (serv.man9) Service Manual ▷ View online
– 9 –
SD-EX200H
Figure 9-2
ADJUSTMENT
Figure 9-1 OUTPUT OFFSET LEVEL
1-bit amplifier's output offset voltage adjustment
Adjust VRA100 and VRA101 so that the DC voltage between
speaker terminals + and - is set to 0
speaker terminals + and - is set to 0
±
5 mV at AC 230 V.
Electronic
Voltage
SO421
AC 230 V
Set
Output:
Speaker Terminal
Speaker Terminal
+
-
VR : 0
Input : AUX
Input : AUX
DESCRIPTION OF CIRCUIT FOR 1-BIT UNIT
(SEE THE WIRING DIAGRAMS ON PAGES 26 AND 27.)
L-CH Output
Offset Adjustment
Offset Adjustment
R-CH Output
Offset Adjustment
Offset Adjustment
VRA101
VRA100
1-BIT AMP. PWB
1-BIT AMP. SECTION
CD SECTION
Adjustment
Input section
Signals from CNA101 are coupled by CA100 and CA101 and
then sent into the A/D converter IC (ICA100).
Signals from CNA101 are coupled by CA100 and CA101 and
then sent into the A/D converter IC (ICA100).
modulation 1-bit converter
Signals from the A/D converter IC (ICA100) are converted to
1-bit signals and sent differentially. Refer to the technical
manual of SM-SX100 for the details of conversion to 1-bit
signals.
Signals from the A/D converter IC (ICA100) are converted to
1-bit signals and sent differentially. Refer to the technical
manual of SM-SX100 for the details of conversion to 1-bit
signals.
Low pass filter circuit
1-bit signals switched by the output IC (ICA101 and ICA102)
are converted to analog signals through the lowpass filter
consisting of LA101 ~ LA107. The low pass filter functions
when a frequency exceeds 20 kHz, and reduces it by approx.
3 dB when it reaches approx. 40 kHz.
1-bit signals switched by the output IC (ICA101 and ICA102)
are converted to analog signals through the lowpass filter
consisting of LA101 ~ LA107. The low pass filter functions
when a frequency exceeds 20 kHz, and reduces it by approx.
3 dB when it reaches approx. 40 kHz.
Dynamic feedback circuit
The 1-bit signals switched by the output IC (ICA101 and
ICA102) oscillate between positive and negative voltage.
After resistance-division, the signals are fed back to the A/D
converter IC (ICA100) through NF resistance 75 kohms (RA155
~ RA158). The peak-to-peak voltage reaches approx. 5 V.
The 1-bit signals switched by the output IC (ICA101 and
ICA102) oscillate between positive and negative voltage.
After resistance-division, the signals are fed back to the A/D
converter IC (ICA100) through NF resistance 75 kohms (RA155
~ RA158). The peak-to-peak voltage reaches approx. 5 V.
Display
