Theory of operation fluke 900 service manual – Fluke 900 User Manual
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Theory of Operation
FLUKE 900 SERVICE MANUAL
debouncing and repeating key actions. The
itest
)
and
inext
)
keys found on the Interface Buffer
are routed through the HSB and optocoupled on the MB to connect to the keyboard CIO. The
chip size LEDs are driven by a latch controlled by this CIO.
The dual UART located at Ull is used for two functions. First, the serial RS232 interface is
connected through a DTE/DCE selectable routing circuit so it can interface to various computers
and printers. Second, various standard frequencies are generated to drive a speaker providing
audible beep tones. The socket at U62 contains the battery and circuit for the real time clock
function.
2-4