Agilent Technologies 8590 Series Service Manual page 275

Table 5-6 A15 Motherboard Mnemonic Descriptions (Continued)
Mnemonic
LOG_LIN Log Linear
LPWRON Low Power On
LTIO Low Top-box
Input/Output
REF_CAL Reference Cal
SWEEP_RAMP Sweep Ramp
VIDEO_IF Video IF
VTO_TUNE Voltage-Tuned
Oscillator Tune
Chapter 5
Full Name
Controls switching between log and linear modes on
the A14 Log Amplifier assembly.
The front-panel line switch provides a TTL low
when the switch is depressed. This initiates
start-up of the A8 Power Supply and A16
Processor/Video assemblies.
Strobe line for Input/Output (I/O) data transfers.
A DAC on the A7 Analog Interface assembly adjusts
the gain of the A9 Third Converter assembly
through REF_CAL.
A 0 to +10 V ramp signal that corresponds to signal
sweep across the display. The signal is sent to J14,
SWEEP OUTPUT, on the rear frame.
The detected 21.4 MHz IF signal from the detector
on the A14 Log Amplifier assembly to the input
multiplexer on the A16 Processor/Video assembly.
A tuning voltage from the A25 Counter-Lock
assembly to A9 Third Converter assembly. It locks
the 600 MHz oscillator on the A9 assembly to the
frequency reference.
Troubleshooting the IF Section
Troubleshooting the A15 Motherboard Assembly
Description
275