Pgm Demodulation Adjustment - Sony CA-550 Maintenance Manual

3-3. TR-90 Board Adjustment

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 1T.
Equipment : Oscilloscope Audio generator
Distortion meter
Preparations :
• PGM level control/at the right-rear→ 2fully 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 1T200 (B-2) until a sign wave appears
around 5.0 Vdc. Adjust 1T200 (B-2) for the following
specifications.
Adjustment Point : 1T200/TR-90 (A-2)
: C = 5.0 ±0.1 Vdc
Specifications
3-8 (E)
5. Adjustment Point : 1T201/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.
4
TR
A
TP203
B
C
D
E
F
G
TR-90 BOARD (COMPONENT SIDE)
3 2 1
T200 T201
E1
CA-550
CA-550P