Agilent Technologies 16900A, Service Manual

Page: 115 / 130

Theory of Operation
8
16900A, 16902A, and 16903A Service Guide 115
configured when the keypad board is assembled. Connector
P1 routes the RS232 microcontroller data to the front panel
interface board.
The front panel interface board provides a connection point
for the three subsystems of the front panel assembly. All
front panel connections are routed to the Module Interface
Board through the one connector J1 that includes keypad
board communication, flat- panel display communication, and
touch screen communication. If the cable to J1 is
unconnected the system will automatically know there is no
front panel assembly and will disable circuitry.
The connector J2 is used as the connection to the keypad
board
The connectors J3 and J4 are connected to a Mitsubishi
12.1” SVGA AA121LS01 TFT- LCD 800x600 display.
Connector J3 provides the data path back to a Chips and
Technologies 65550 Video Adapter. Connector J4 is used to
provide the high- voltage needed to light the display
backlight. This high- voltage is generated using a power
inverter board, which is mounted on the front panel
interface board. This power inverter board is a Taiyo Yuden
LS720A DC- AC 1500 VRMS.
The connector J5 is used to connect to a touch screen
controller board. This touch screen controller board is
mounted on the front panel interface board and is a 3M
SC4. Mounted in front of the flat panel display is a touch
screen grid connected directly to the touch screen controller.
This controller interprets touch presses and communicates
back the host CPU via +15 V RS232.
16900A/16902A/16903A Power Up Routine
The power up routing includes the following:
• Boot sequence (more on page 115 )
• Product install (more on page 118 )
• Software recovery methods (more on page 119 )
• Self test (more on page 119 )
Boot sequence
The 16900A/16902A systems ship with the Windows XP
Professional operating system. After power is applied to the
frame, the basic input/output system (BIOS) is the first thing
to run. Among other things, the BIOS is responsible for