Out; Overview; Protect - Sony TVP-08 Training Manual

Overview

The main purpose of the V Out circuit is to amplify the V Drive signal and
apply it to the yoke. There is also a V protect circuit that senses the loss
of V Output operation and sends a HIGH to the IC1009 and the latch
circuit to alert the Self-Diagnostics circuit and shut down the set.
V Out
The V Drive signal is sent from the VDSP on the A board to the D board
through CN5004/2. This goes through R5021 and R5043, and enters
IC5004/1 Inverting Input. IC5004/7 Non-Inverting Input has a DC refer-
ence voltage of 1.25 Vdc input to it. This DC voltage effects the vertical
centering position. IC5004 V Out amplifies the input signal and outputs at
pin 5. The signal output is approximately 55 Vpp. This is possible even
though the difference in supply voltage is only 30 volts because of the
voltage boost circuit inside IC5004. This circuit outputs a pulse that boosts
the positive supply voltage by increasing the charge of C5037 during re-
trace. The time at which this occurs is evident by looking at the output
waveform.
IC5004/5 outputs a signal that is applied to the vertical yokes, which are in
series through L5009 and R5076. C5048, C5047 and R5077 act as a
damper circuit. C5089, C5040 and R5059 are used for protection pur-
poses. R5047 is the main feedback component. R5071, R5067 and
TH5001 also have an effect on the gain of the amplifier. TH5001 is used
for temperature compensation. As the circuit operates, the vertical yokes
become hot and their resistance increases. When this occurs, R5067
and R5071 become hotter. When they heat up, the resistance of TH5001
is lowered because it is located in close proximity to these resistors. This
allows more current for the yokes so that the picture is not effected. C5028
is there to prevent oscillation.
V Out
91
V Protect
The voltage boost pulse from IC5004/3 is applied to a peak detect circuit
consisting of C5034, D5010, R5040 and C5023. As long as these pulses
are present, they cause C5023 to hold a charge. This charge causes .6
volts to be present at Q5005/B. This voltage keeps Q5005/C to be LOW.
If the pulses should disappear, C5023 would not charge due to the block-
ing action of C5034. This would cause Q5005 to turn OFF and allow 5
volts to be present at Q5005/C. This would activate the protect latch and
also inform IC1009 that a failure has occurred.
V Protect Delay
Q5010 is the V Protect Delay and delays the operation of the V Protect
circuit until C5013 charges. When the set is turned ON, current flows to
ground through Q5010 B-E junction and C5013. This allows for .6 volts to
be present at Q5005/B until C5013 charges. The voltage boost pulse
should be present at this time. If it is not, the V Protect line will go HIGH
and the set will shutdown.
CN5004/2
V Drive
2V 5ms
IC5004/3
Boost Pulse
10V 5ms
IC5004/5
V Out
10V 5ms