HP 8924E, Assembly

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Chapter 10, Service Screen
Troubleshooting with the Service Screen
N:\mkt\MANUALS\HP8924C\ALR\service.fb
Field Names and Descriptions
Voltmeter Connection
This field selects the desired circuit node for voltage measurements. To change
the voltmeter connection, move the cursor in front of the
Voltmeter
Connection
field and push the cursor control knob. A
Choices
menu will
appear. Move the cursor to the desired circuit node in the list and push the cursor
control knob. The reading is displayed in the
Voltage
measurement field at the
top left of the display.
Because the diagnostic MUX points being measured must be in the range of 0 to
±5 volts, the measurement of some points are scaled to that measurement range.
For example; the +12 Volt reference (
MEAS_12V_REF
should measure about
+5volts. The -12 Volt reference (
MEAS_NEG_12V_REF
should measure about -5
volts. Many of the voltage measurements are only valid after a number of
instrument settings are changed.
When run, the diagnostic routines make the necessary circuit changes and
measurements automatically, comparing the measurements to known limits for
each node.
Counter Connection
This field selects the desired circuit node to connect to the Test Set’s internal
frequency counter. The reading is displayed in the
Frequency
measurement field
at the top right of the display.
To change the counter connection, move the cursor in front of the
Counter
Connection
field and push the cursor control knob. A
Choices
menu will
appear, then move the cursor to the desired circuit node and push the cursor
control knob.
Gate Time
This field is used to adjust the Test Set’s internal frequency counter’s gate time. A
shorter gate time may enable you to see frequency fluctuations that might not be
seen using a longer gate time.
To change the gate time, move the cursor in front of the Gate Time field and push
the cursor control knob. Rotate the cursor control knob until the desired gate time
(10 to 1000
µ
in 10
µ
increments) is displayed, then press the cursor control knob.