G2 Control And Spot Killer - Sony CPD-420GS Training Manual

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G2 control and Spot Killer

The G2 source voltage from the D board enters the A board via CN301/1
via R048 and R064. The node between R048 and R064 is connected to
the CUTOFF CTRL circuit comprised of IC005 and Q001. The G2 adjust-
ment can only be performed using the DAS/CATS Software or the Color
Restoration function (explained later). The Micro IC1001 (N Board) via
the I 2 C bus instructs IC001 to vary the DC level of pin 6 (G2). This volt-
age is routed to the non-inverting input of IC005/5 (CUTOFF CTRL). The
DC output from pin 7 (OUT) is input to Q001/E and output at Q001/C
configured as a common base amplifier. Q001/C is connected to the
node between R048 and R064. By varying the DC voltage at this node,
the DC level at J001/10 G2 of the CRT can be adjusted. C028 provides
bias to Spot Killer Q001/B during power OFF, reducing the G2 voltage to
minimum.