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Chapter 2—Functional Description
Model 330, 340SC and 370SC Service Manual 2-53
High Voltage Power Supply
Outputs
Description
VDFOCUS
Parabolic waveform of vertical frequency.
HDFOCUS
Parabolic waveform of horizontal frequency modulated by the
VDFOCUS waveform.
/HVEN
Enable signal for HVPS, used to shut down HVPS for CRT
protection.
System Power Supply
Inputs
Description
+5V
Power supply to digital components.
GND
Return from digital components.
+15V
Power supply to analog components.
-15V
Power supply to analog components.
GND (TP 0)
Return from analog components.
Interlocks and Protection
Input
/SWEEPOK
TTL high indicates that one or more of the sweeps, either horizontal or
vertical is not at or above the minimum amplitude and frequency. This will
cause a cutoff so that RVOUT, GVOUT, and BVOUT will be pulled low.
Additionally, /RENABLE, /GENABLE, and /BENABLE will be pulled high
resulting in shutdown of grid bias at the Video Output Boards. Also, the
SWEEPOK status bit will be transmitted to the SCB.
RBEAM
Signal representing average red CRT beam current at 1mV/1uA. At greater
than 0.7V, causes contrast and overlay intensity on all three colors to be
reduced.
GBEAM
Similar to RBEAM.
BBEAM
Similar to RBEAM.
/RVIDOK
High indicates low voltage at the +100V supply on the red Video Output
Board. This causes a low at the VIDOK status bit sent to the SCB over the IIC.
The /HVEN signal is allowed to go high shutting down the HVPS.
Additionally, a high cutoff signal is sent so RVOUT, GVOUT, and BVOUT
will be pulled low. /RENABLE, /GENABLE, and /BENABLE are also pulled