Mitsubishi V19-V21, Tehnical Manual

Page: 56 / 71

8-4
HV 12 Volt Supply
Figure 8-3 shows the HV 12V supply circuitry. The
source of the supply is the 24 Supply from the Main
Power Supply, applied to the collector of Q5A08. A
10 volt reference, from IC5A03 is applied to the in-
verting input of an Op-amp in IC5A01. A sample of
the voltage at the emitter of Q5A08 is applied to the
non-inverting input.
The output of the Op-amp controls the conduction
of Q5A08. Conduction increases if the voltage at
the emitter drops below 12 volts, and decreases if
the voltage exceeds 12 volts. The HV 12V supply is
routed through a jumper in the DK connector to
IC5A00.
The DK connector is connected to the ground re-
turns of the HV Block. If the set is operational with
the DK connector unplugged, excessive HV would
be generated causing damage to the TV. The jumper
in the DK connector insures that the HV is disabled
when the connector is unplugged.