Note
When measuring voltages or waveforms, make ground connections to
A2TP3.
The metal board-standoffs are not grounded and should not be used when
taking measurements.
Troubleshooting Using the TAM
Refer to Chapter 7, “General Troubleshooting,” for information on enabling the TAM for use
with the HP 85623 Spectrum Analyzer.
Table 10-l lists assembly test connectors associated with each Manual Probe Troubleshooting
test. Figure 10-l illustrates the location of the A2 test connectors.
IC
onnector
A2Jll
Blank Display
Measured Sienal Lines
MSl,
MS3 through MS6, MS8
MS2.
MS7.
OS1
Table 10-l. TAM Tests versus Test Connectors
Manual Probe Troubleshooting Test
ADC/MUX Test
DAC test
10 volt reference test
Switch drive test
Buffered X
&
Y DAC outputs
X line gen test
Y line gen test
Intensity offset output
Revision
X, Y,
&
Z Output Offset
X output amplifier
Y output amplifier
Blanking test
Focus DAC test
MS4
MS8
MS2, MS7
MS6
MS1
MS3
MS1
MS3, MS4, MS7
MS7
MS3
MS8
MS2
Use the following procedure if the instrument display is blank. This procedure substitutes an
HP-IB printer for the display.
1. Connect the printer to the spectrum analyzer and set the printer address to the value
required by the TAM. This is usually 1.
2. All of the power-supply indicator LEDs along the edge of the A2 controller assembly
should be lit.
3. The rear-panel CRT
fll0
VDC ON indicator might not be lit, even if the
-t-110
V is
present.
4. Connect the TAM probe cable to
A2Jll.
5. Press
(-1,
SDFT
KEY
#3,
a,
SQFT
FFY
#I
. (The top
softkey
is
#l.)
6. The yellow LED next to
A2Jll
should blink approximately ten times. If the LED fails to
blink correctly, troubleshoot the digital section of the A2 controller assembly.
1 O-2
Controller Section