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Microprocessor
Figure 23
The Microprocessor, 7064, is located on the SSB. User control of the Microprocessor is accomplished via the
Keyboard or Remote. In case of Overcurrent or a failure in the Horizontal sweep circuit, The PROT-UP line will
go High turning transistor 7276 On, placing a Low on Pin 5 of the Keyboard line. The Microprocessor will then
shut the set Off. Composite Video for Data capture, for Closed Caption or Text, is fed to the IC on Pins 32 and
31. The Microprocessor is connected to the Memory IC 7066, which stores information for Option Codes,
Geometry, Gray Scale, and Customer settings. Two I2C busses, SDA and SDA-2, communicate with the set
along with several analog outputs. The set is turned On when the STAND BY line on Pin 13 is pulled Low by
7064. Horizontal and Vertical sync for the On-Screen display is fed to the IC on Pins 53 and 55. The Reset for
the Microprocessor is located on the SSB. Transistor 7063 turns Off as 2043 charges causing Pin 73 to go High
when power is first applied to the set for Reset. When the set is operating normally, the Reset pin should
measure Low. The FRONT-DETECT line monitors the Side Jack panel for the Headphone or an SVHS
connection. It also monitors 7992 for a Power Down. A Low on Pin 6 will disable the Keyboard and IR inputs.
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