A27 Mass Storage Disk Drive; A28 Fdd (Floppy Disk Drive); A51 Lcd (Liquid Crystal Display); A52 Inverter Board - Agilent Technologies E4991A Service Manual

Theory of Operation
Digital Section

A27 Mass Storage Disk Drive

A27 mass storage disk drive is a 2.5 inches hard disk drive. The disk drive is used to store
the operating system, firmware, and user's measurement data. The drive is mounted with
shockresistance, but be careful for the mechanical handling.

A28 FDD (Floppy Disk Drive)

A28 FDD is a 1.44 MBytes, 3.5 inches, MSDOS compatible, and it is located on the front
panel. The FDD is used to store the measurement data and the instrument setup data.

A51 LCD (Liquid Crystal Display)

A51 is an 8.4 inch color TFT LCD. It consists of the LCD display and the backlight. Video
signal is provided from A26 Display Board through a flat cable.
A high voltage is supplied from A52 Inverter to the LCD's backlight. The backlight
determines the brightness of the LCD screen.

A52 Inverter Board

A52 generates a high ac voltage required to drive LCD's backlight.
224 Chapter 5