Sony CA-550, Maintenance Manual, Page: 36 / 114

3-8 (E)
CA-550
CA-550P
3-3-9. PGM Demodulation Adjustment
Note :
• This adjustment is necessary only when replacing T200
or T201 on the TR-90 board.
• Use a plastic core driver to adjust
1
T.
Equipment : Oscilloscope Audio generator
Distortion meter
Preparations :
• PGM level control/at the right-rear
→
2
fully clockwise
• CCU-700/700P/700A/700AP setting
Extend the AT-88 board of the CCU.
S2081 (PGM IN 0 dB/-20 dB)/AT-88 (D-5)
→
0dB
S2082 (PGM MIX ON/OFF)/AT-88 (F-5)
→
OFF
Test Point :
Pin 5 (X), Pin 3 (G)/
INCOM connector
Adjustment Procedures:
1. Feed an 1.0-kHz sine wave signal from the audio
generator to pins D68 (X), A69 (Y), and B69 (GND)
on the extension board (extending AT-88) referring to
Section 3-1-3 “Connection — For audio adjustments”.
2. Adjust the audio generator so that the level at TP44
(GND:E1)/AT-88 (L-7) is 200 mVp-p.
3. Connect the oscilloscope to TP203 (GND:E1)/TR-90
(B-3).
4. Slowly turn
1
T200 (B-2) until a sign wave appears
around 5.0 Vdc. Adjust
1
T200 (B-2) for the following
specifications.
Adjustment Point :
1
T200/TR-90 (A-2)
Specifications :
C = 5.0
±
0.1 Vdc
5.
Adjustment Point :
1
T201/TR-90 (B-2)
Specifications :
The distortion is 0.3% or less
and minimum.
Note :
• After the adjustment is complete, be sure to return S2081
and S2082/AT-88 to their customer-set positions.
TR-90 BOARD (COMPONENT SIDE)
3-3. TR-90 Board Adjustment
A
1 2 3 4
B
C
D
E
F
G
TR
T200 T201
TP203
E1