Circuit Explanation - Haier 21FA18-T Service Manual

7. Circuit Explanation

1、Microprocessor and Small signal processing: super monolithic integrated circuits ：
Haier8873
Haier8873CSN is super large integrated circuit decoder, containing intermediate image
amplifying, intermediate sound amplifying, horizontal and vertical scan, small signal
processing, color decoding, hi-pressure tracing and over-load protection, I
Information introducing functions and testing data for maintenance is listed in Table 1.
Table 1
Step
1
U/V
2
L/H
3
KEY INPUT
4
DIGITAL GND
5
CPU RESET
6
X.TAL
7
X.TAL
8
TEST
9
+5 VCC
10
GND
11
SIGNAL GND
12
HORIZONTAL SYNC SIGNAL INPUT
13
HORIZONTAL RETURN PULSE
SIGNAL INPUT CHARACTER
HORIZONTAL LOCATION
14
HORIZONTAL AFC
15
VERTICAL SIGNAL PRODUCE
LOCATION
16
VERTICAL RETURN PULSE SIGNAL
INPUT CHARACTER VERTICAL
LOCATION
17 HORIZONTAL VCC
18 GND
19 Cb SIGNAL INPUT
20 Y SIGNAL INPUT
21 Cr SIGNAL INPUT
22 EXT AUDIO
23 COLOR SIGNAL INPUT
24
EXTERIOR VEDIO SIGNAL INPUT2
ALL FILTER
25
26
VEDIO SIGNAL INPUT
27
ABCL-IN
28
AUDIO OUTPUT 1
Function
Working Ground Resistance (R)
Voltage
Positive
(V)
(Ω)
0 600
1.8 600
5 600
0
5 600
2.3 600
2.0
0
5 400
0
0
1 750
1.7 500
6.3 750
4.3 750
5.3 750
8.7 100
0 700
2.4 750
2.4 750
2.4 700
0
0
2.4 700
3.4 320
2.6 750
4.5 750
3.5 750
19
2
C bus control.
Negative
(Ω)
5000
5000
15000
0 0
10000
1000
600 15000
0 0
4500
0 0
0 0
150
550
1400
1500
1300
100
900
5000
5000
4500
0 0
0 0
4500
300
5000
5000
1400