cxa1202q-z Sony Electronics, cxa1202q-z Datasheet - Page 21

• Manufacturer Part Number: cxa1202q-z
• Description: Rec/pb Amplifier For Vcr
• Manufacturer: Sony Electronics

Precautions
1. Do not connect parasite capacitance to REC AMP dumping.
2. Do not bring Head AMP input near PB output.
3. Use 150k for RF AGC time constant, Resistance
4. Watch the time constant of dropout detection.
5. Take AFM PB output from V RF OUT (Pin 20)
6. Adjust tape path by mixing V RE OUT signal and PCM RF OUT signal. In the absence of a signal before
Normally, there is a gain of 67dB between Head Amp input (Pins 29, 30) and RFOUT (Pin 16). During no
signal, the gain is 74dB (as AGC reaches maximum gain). Bringing those closer on the pattern may cause
oscillations in the vicinity of 6 to 7MHz.
Because a change in this R causes a change in the AGC output level, change the time constant using the
value of capacitance.
Passing AFM signal through RF AGC causes AGC to reach maximum gain when playing back a virgin tape.
As a result MUTE may not apply to AFM IC (CX20137, CX20037).
switching, observe the envelope comprising the combination of the VIDEO area and the PCM area by
mixing outputs from V RF OUT (Pin 20) and PCM RF OUT (Pin 8).
DOC TC
28
15
C
PCM RF OUT
1
V
After mixing
REC AMP
CC
V RF OUT
RF SWP
C
R1
R2
2
C
C
1
25
– 21 –
Time constant: t = C
C: over 150pF
R1, R2: 5
Oscillations may occur unless this condition is satisfied.
Effect of C
R1 + R2
R2
Frequency
1
(R1//R2)
= 1.2 to 2.0V
Effect of C
CXA1202Q-Z/CXA1202R
2