Service manual

CB-7
Microprocessor Control
the corresponding tuner to allow for clearer channel reception. The ideal voltage level here should be
between +2.25 and +2.5 volts.
<<Figure CB-7>>
IC6000 provides CRT-protection for the set through pin 13. Operation of this shutdown depends on a DC
level from the CRT protection circuit off the vertical amplifier circuit. Should the vertical IC2100 fail, the
DC level will no longer be present. In this situation, the CRT-protection latch will shut the receiver down
three seconds after detecting the failure. This circuit will prevent the CRT from burning a horizontal phos-
phor line in the center of the screen or, worse yet, cutting the yoke end of the tube off completely.
The remainder of the I/O pins on IC6000 are briefly described here. Where necessary, a more detailed
description will be provided in the circuit descriptions to which they relate. Pins 10, 11, and 12 are used as
S-Video (Y/C) detection for the two Y/C jacks on the back and the Y/C jack on the front (where avail-
able). Pin 48 emits a varying DC level that changes the bias on Q2211, effecting the PiP brightness of the
RGB input to IC2200. Audio swap is accomplished by pin 44, which varies a DC level to a transistor array
in the IF section. This array allows the audio signal being heard by the user to be switched between the
primary and secondary IF. Pin 42 controls the Gemstar
®
modules reset function. Pin 41, the YUV-SW
varies a DC level on pin 36 of IC2200 to make it switch main video between separated luma and chroma
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
36
26 27
28
29
30
31
32
33
34
35
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
HSYNC
VSYNC
AFC
N/C
SD2
SD
KEY1
KEY2
AFC2
Y/C1-SENSE
Y/C2-SENSE
Y/CF-SENSE
CRT-PROT
MUTE
IR DET
N/C
N/C
AVDD
HLF
RVCO
VHOLD
CVIN
CNVSS
XIN
XOUT
VSS
R
G
B
FB
PiP-BRIGHT
N/C
N/C
N/C
AUD-SWAP
N/C
GM-RESET
YUV/SWITCH
H/T
SCL1
SCL2
SDA1
SDA2
IDENT
N/C
DEG-CTL
POWER
N/C
RESET
OSC-OUT
OSC-IN
VDD
IC6000
C6012M
C6013
L6001
+5VSBM
+5VSBF
C6017
R6037M
C6016
C6056M D6001
C6014M
R6059M
CRY6002
PROV
L6002
R6060MR6035M
C6015M
C6018M C6045M
C6046M
Deg-Ctl
Power-Ctl
C6024M
C6025M
C6033M
C6023M
R6081M
C6065MR6024M
C6067M
R6088M
C6091M
Q6003
J6001M
C6046M R6023M
C6063M
C6055M
1
2
3
R6062M
PROV
R6061M
PROV
D6004
PROV
R6071M
PROV
C6054M
C6038M
C6039M
R6040M
R6058M
C6057M
R6068
C6068M C6052M C6062M
C6053M
VCC
GND
OUT
IC6002
Power-Fail
YUV-Switch
GM-Reset
PiP-Brightness
Aud-Swap
Halftone
FB-Micro
B-Micro
G-Micro
R-Micro
FB-PiP
4Q9
IQB32B44W
IQB36B44W
ONLY