Agilent Technologies 89410A Service Manual page 99

2
Check the channel 1 auto-range signals.
a
Place the analyzer on the side closest to the display.
b Remove the bottom cover.
c
Press the following keys:
0
[ dBm ]
[ ]
Marker/Entry
d Using a BNC cable, connect the SOURCE output to CHANNEL 1
input.
e
Using a logic probe, check the TTL signals listed in the following
table. Rotate the RPG knob to change the source's amplitude to
an under-range and over-range condition.
Signal
Test
Name
Location
A91 P1 pin 47 nOVRRNG1
A91 P1 pin 48 nHLFRNG1
A91 J2 pin 11B nADCOVR1
f
Press the following keys:
]
[
Range
[
ch1 autorange up-down
[ ]
Source
g
Rotate the RPG knob until the analyzer changes its range.
When the analyzer changes its range, the signals in the above table
should toggle.
h If the analyzer does not have the optional second channel and the
signals are correct, the A30 Digital Source assembly is probably
faulty.
To troubleshoot auto-range failures
Input Input Under Input Over
Range Range Range
Correc (<-10 dBm) (>+6 dBm)
t
High High Low
Low High Low
High High Toggling
]
Troubleshooting the Analyzer
Probable
Faulty
Assembly
A36 Trigger
A36 Trigger
A21 A/D Converter
1-81