Block Diagrams
Theory of Operation
2 - 66
0070-00-0420
Passport 5-Lead, 5L, LT, XG Service Manual
Alarm LED
The Alarm LED is a high intensity red LED. It is driven by a FET, a 2N7000 which is controlled
by the signal LED0 from the CPU.
Speaker Interconnections
The EL/LCD Panel Board provides connection from the CPU board to the speakers.
Keyboard Interconnections
The four input lines KI0 through KI3 and the eight output lines KD0 through KD7 provide
interconnection between the CPU board and the 8 by 4 matrix keyboard. A jumper on line
KI3 to KD3 and KD4 is used to indicate which display is being used.
DC/DC Converter
The power supply on the Panel Board is a DC/DC converter. The input voltages to the power
supply is from the Line Battery Board which improves the power management of the system.
The input voltage range for the DC/DC converter is 9 to 18 Volts. The power supply provides
a +12V @ 1.250 Amps Max. for the monochrome EL display.
2.2.11
Termination Board
Overview
The Termination Board’s function is to help reduce emissions from high speed EL/LCD display
signal outputs and 5 VDC power from the CPU board (P/N 0670-00-0651) in the Passport.
The Termination board is inserted between the output connector J68 on the CPU board and
the ribbon cable (P/N 0012-00-0744) that connects to the EL/LCD Panel board (P/N 0670-
00-0617).
Common Mode Choke
The common mode choke is a ferrite device that reduces conducted emissions on signal or
power lines without affecting transmission. The ferrite acts as an attenuator to high frequency
signals by absorbing extraneous and unwanted energy. Low frequency and DC signals see
only the conductor and are unimpeded without any loss. High frequency signals encounter
inductive resistance due to the ferrite providing the insertion loss for dissipating EMI. Since
this choke is common mode it attenuates unwanted common signals on both the power and
digital ground.
FIGURE 2-29
Termination Board Choke Assembly
31
32
33
34
31
32
33
34
40
5 VDC
DGND
5 VDC
DGND
SHIELD
P68
J71
Summary of Contents for Passport 5-Lead
Page 1: ...Service Manual 5 Lead 5L LT XG Datascope Passport 0070 01 0420 indd 1 4 11 11 4 45 PM...
Page 2: ...5 Lead 5L LT XG Service Manual Datascope Passport 0070 02 0420 indd 1 4 11 11 4 45 PM...
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