Philips DPTV305, User Manual

Page: 88 / 1848

Intellisense Sensing Circuit
Figure 35
The output of the four sensing Solar Cells are fed to IC 7141 located on the ACS module. Inputs
TBU0, TBU1, and TBU2 from the Convergence Microprocessor are fed to the Decoder which selects
the Solar Cell to be read. The output on Pin 3 is fed to Pin 2 of 7140-A. 7140-A matches the low
impedance output of 7141 to the high impedance input of 7140-B. Amplifier 7140-B charges capacitor
2253 with the sample voltage. Due to the high input impedance of 7140-C, 2253 will hold the sample
voltage until it is cleared by transistor 7540. The output of 7140-C is fed to 7101 which is an Analog to
Digital converter. The Digital reference voltage is fed to the ACS microprocessor where the data is
processed and recorded. When the next location requires sampling, a High is output on Pin 100 of
7100. This turns Transistor 7540 On discharging capacitor 2253.
The Basic version of the HDRPTV does not have the Sensors installed in the set. However, the
Sensor Test is in the Service Convergence menu. When the Convergence alignments are stored, the
Microprocessor will attempt to read the Sensors. If the Sensor test is selected in the Convergence
Alignment menu, the message will read “Sensors not verified at locations: 1234.” This will not affect
the Convergence alignments.