Mitsubishi V19-V21, Tehnical Manual

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7-8
CRT Drive & Protect Circuitry
Figure 7-7 illustrates the CRT Drive and CRT Protect
circuitry. The CRT Drive circuitry is the same as that in
the V17, except that the three discrete component tran-
sistor amplifiers on each PCB-CRT are replaced with a
single IC, IC6B01, IC6G01 or IC6R01. Only the PCB-
CRT(B) is shown in
Figure 7-7 .
Transistors Q2W05, Q2W08 and Q2W11 are part
of the CRT Protect circuitry. When these transistors
conduct it removes the drive to the CRTs. Q2W03
controls the conduction of all three of CRT Protect
transistors.
The conduction of Q2W03 is controlled by the
VBLNK and BLANK CRT lines. The BLANK-CRT
line momentarily goes Low during a channel or input
change, momentarily blanking the CRTs.
The VBLNK line goes High if deflection is lost. The
High turn Q2W03 On, blanking all three CRTs to
prevent possible CRT phosphor damage.
In the V17 Spot Killer circuitry was also part of the
CRT Protect circuitry. This circuit has been replaced
by Flash Protect circuitry. The Flash Protect circuit
and Deflection Detection Loss circuitry are described
in
Chapter 8.
Monitor Out Signal Path
The Video/Color Monitor Signal Path is shown in Fig-
ure 7-8 . NTSC signal for the Monitor Outputs is de-
rived from the C output of the 3DYC Comb Filter, and