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DC Standby supplies are generated in the secondary
circuits of T9A20, these include STBY 6V, STBY
12V and STBY 32V. STBY 5V supplies are de-
rived from the STBY 12V, and STBY 28V from the
STBY 32V.
The STBY 12V and STBY 32V supplies are gener-
ated by rectifying the same secondary winding sig-
nal.
Figure 5-2 illustrates how this is accomplished. The
positive part of the signal from the secondary wind-
ing is rectified by D9A30 to generate the STBY 12V
supply. The same signal is directed through C9A32
to the anode of D9A32. The anode of D9A32 is
clamped at 12 volts by D9A31 and the 12 volt sup-
ply. The combination of the clamping action and
rectification of the signal from C9A32 generates the
STBY 32V Supply.
CAUTION: The primary section of the regulator is
referenced to a Hot Ground. Use an Isolation
Transformer when working in the Primary circuitry.
Note in Figure 5-1, that voltage sources rectified by
D9A01, and D9A27 are both directed to the Switch
Mode Regulator for the Switched Supplies .
Switched Supplies Regulator
Figure 5-3 shows the Switched Supplies Switch Mode
Regulator. Except for component nomenclature its'
operation is the same as the Standby Regulator.:
1) Startup and the oscillators DC supply are input
at pin 4 of IC9A50.
2) The SW 110V supply is monitored for
regulation and is directed via IC9A51 and
PC9A51 to pin 1 of IC9A50.
3) Switched supplies are generated by rectifying
secondary winding signals.
On/Off Circuitry
Due to the V19/V21 Time r Recording feature, two On/
Off commands are required. Time Shift Recording en-
ables using the TV's Tuner as the signal source for a
VCR pre-programmed recording, without switching the
TV completely On.
The On/Off circuitry is also shown in Figure 5-3.
There are two Power On commands, P-ON1 and P-
ON2. P-ON1 activates the Standby Regulator,
IC9A50. IC9A50 generates 220V, AUDIO (17V),
+24V, -24V and 110V Switched Supplies. P-ON2
activates the 12V and 5V Switched Supplies, which
supply power to the signal processing circuitry.
5-3
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