78
18. RA-5A Deflection Circuit Troubleshooting
IC8005
H DRIVE
CTL
2
3
6
14
T8003
HOT
1
4
3
2
1
H OUT
H RET
1
4
2
1
3
5
H OUT
H RET
1
4
H OUT
H RET
1
4
T8002
HDT
Q8020
Q8016
Q8004
Q8030
Q8023
Q8024
H OUT
Q8031
Q8101
H PULSE
TO A BOARD
Q8039
IC8012
IC8019
HLC
C8137
D8032
D8045
DYB
DYR
DYG
H CENT.
+
-
+
-
Q8027
135V
200V TO
DF CIRCUITS
FROM
E-W
IC3006
PIN 47
A BOARD
12V
D8033
FROM
H DRIVE
IC3006
PIN 40
A BOARD
IC8009
112VDC
+
FIGURE 18-1 - HORIZONTAL DEFLECTION RA-5A CHASSIS
18.1TVP14 1468
7/10/02
Vertical Deflection Troubleshooting
No Vertical Deflection: The first instinct of the technician is to go after the vertical output IC5004 and understandably
so. It is a drive component with heavy current usage and heat dissipation, and it is usually the cause of the
failure.
The first check that you should do (and this applies to all Sony televisions of the last seven years) is to check the
voltage level of the clock and data lines on the I
2
C bus. They are conveniently labeled SCLK and SDAT. The DC
voltage should not be lower than 4.6 volts. If either of these lines is loaded down, the vertical oscillator will not
start. This is the number one cause of multiple component replacement for a simple vertical problem. You
should always check the clock and data level whenever you have a strange problem and, particularly, if it appears
that you more than one problem. Although most television chassis’ will not produce vertical deflection, some will
generate other symptoms. As an example: The AA-2W used in Sony’s KV32/36XBR200 sets will display a
magenta colored raster with no video and insufficient vertical height. Assuming the bus is okay, move onto the
next step.
Since this chassis will go into protect mode and shut the unit down, certain measurements must be taken and
watched for during the time the unit powers up and shuts down. Unlike previous designs, the V stop feature
cannot be overridden since pin 35 of IC3006 is looking for vertical feedback ramp pulses from the yoke return.
Always remove the C boards from the tubes when servicing a no vertical sweep condition.
The ± 15V lines are the first to check. If OK, place a scope probe and watch for a moment of vertical sawtooth
signal at pin 1 or 7 of IC5004. Any presence of drive signal here indicates IC3006 is generating V drive and
isolates the problem to the output circuits. Verify vertical ramp signal on the high side of R8036 or R8039 in the
return circuit. The circuit could be running and Q8001 is not sending the V signal to IC3006.