The Red output from Pin 40 of 7600 is buffered by 7700 and 7701. The R-BIAS controls the gain of
the circuit.
The drive of the Red and Green outputs are compared with the Blue drive by 7900-A. The difference
signal is fed back to 7600 via the ABL line. If the Blue CRT is driven harder than the Green and Red
CRTs, the inverting input on Pin 2 will become greater than the non-inverting input on Pin 3, resulting
in the output on Pin 1 to go Low. The ABL line will go Low, causing 7600 to reduce the drive to all of
the CRTs. This circuit prevents the Blue tube from being over driven.
HOP Analog Control
Figure 26
IC 7800 develops the analog control voltage for the HOP panel. The I2C bus controls the IC. This IC
is located on the HOP panel. The Microprocessor that controls this IC is located on the ACS module.