Sony TVP-08, Training Manual

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17
Converter
Overview
Simply put, the converter circuit switches the DC Switching Supply B+ ON
and OFF to create an AC signal. The converter in this set consists of two
Driver ICs that drive two sets of N-channel MOSFET transistors. The
drivers use the output signal from the oscillator to switch the transistors.
These transistors are switched 180 degrees out of phase and are parallel
with the two Power Input Transformers.
Operation
Two signals 180 degrees out of phase are applied to the Hi and Lo side
inputs. The Hi side input of IC6002/10 is the same phase as the Lo side
input at IC6004/12. The Low side input at IC6002/12 is the same phase
as the Hi side input at IC6004/10. These signals are amplified and output
in phase with their inputs.
The Hi side of each of these drivers has a floating power supply that
boosts the output level of the signal. The input to this supply is at IC6002/
6 and IC6004/6. The return is at pin 5 of IC6002 and IC6004. This float-
ing supply allows a 130 Vpp signal to be output for each Hi side driver.
If IC6002/7 is outputting a High signal, then Q6008 turns ON. When
Q6008 is ON, it allows the 130-volt Switching B+ to be present at Q6008/
S. This voltage is applied to IC6002/6, the floating supply input, and also
to C6022 and C6023. The signal seeks ground through Q6009, which is
always ON when Q6008 is ON. Current flows through the transformers
T602 and T601 while C6022 and C6023 are charging. At the same time,
the signal outside of IC6002/1 Lo side output is Low. When the signal at
Q6008/G goes Low, the signal at Q6007/G goes High. This causes C6022
and C6023 to be connected to ground. At the same time, Q6010 is turned
ON and Q6009 is turned OFF. This causes current to flow through the
transformers T601 and T602 and capacitors C6022 and C6023. This
cycle continues while the set is running and causes sine waves to be
seen at T601/1 and T602/4. This signal is induced into the secondary of
the transformers to produce the power supply output.