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b.
Use signature analysis to verify that the input port is
being addressed and enabled.
c.
If both the above are correct, the input port I.C. is
probably bad.
To check output ports:
a.
Switch unit to LED test mode.
b.
Check the output port of any malfunctioning LED
with a logic probe (the signature analyzer probe also
operates as a iogic probe).
c.
The output port should be low (ground) when the
LED should be on, and high (+ 5 volts) when the
LED should be off.
d.
If the logic levels are correct, check the LED.
e.
If the logic levels are incorrect, use signature analysis
to verify that, the output port is being addressed and
enabled.
f, if more than one LED on a given IX. does not light,
either the I.C. or its enable input is probably bad.
5-100
After troubleshooting be certain to restore to normal
operating condition any of the following that may have been
changed.
1.
Sensing and other rear-panel connections.
2.
TP1
to TP2 or TP3 on HP IB/microcomputer
assembly (grounds '\1/ and\^7).
3.
TP11 to TPM on HP IB/microcomputer assembly
(signature analysis interrupt).
4.
Signature analysis free-run jumper pack.
5.
Bias power supply jumpers J2 (5 jumpers), and J5 (3
jumpers) on HP-1 B/microcomputer assembly.
Table 5-6. HP-IB/Microcomputer Bias Supply Voltages
Unregulated*
Test
Minimum
Maximum
Nomina!
Point
Valley
Peak
HP-IB BIAS VOLTAGES
4 5
A5-W/YEL
11.4V
18.0 V
4-12
A4F1
17.5 V
27.0 V
Regulated (+5%)
A5-W/BLU
0.75 A
asured at
rmally 0 V
1 Api
+ 5
4 12
+
15
-
15
A5-W/ORN
A4CR7Cath
A4CR7Cath
A4CR6 Ano
11.4 V
17.5 V
17.5 V
.17.5 V
19.0 V
2.7.0 V
27.0 V
.27.0 V
A5W/RED
1 A
60 mA
60 mA
60 ntA
A4J2
PON2, Measured at A4B.75 Normally 0 V
SJ/TP2 and TP3
* Observe unregulated voltages with an oscilloscope.
HP-IB common (\T ) is isolated from microcomputer and power mesh/control board common <\2/). A potential across
A4R65 (PON 1) or A4R75 (PON 2) indicates low bias voltages. A problem with unregulated voltages on either side of isolation
will cause the PON signal on both sides to go low. The two PON signals communicate with each other through
photo isolators A41J88 and A4U89. These signals protect the 6034A from trying to operate with low bias voltages.
The blue A4J2 and A4J5 jumpers should be removed to disconnect the bias voltages while troubleshooting the HP-IB or
microcomputer bias supplies. In this way the user can determine if the bias voltages are being pulled down by a short circuit.
To ensure that the bias supplies can operate under load, use the current values listed to select a resistor of the proper value to
simulate full load. Connect the load resistor to the bias supply output with the output jumper removed to check that the bias
voltage remains within regulation under load.
Remember to reconnect the J2 and J5 jumpers after correct operation of the bias supplies has been verified.
5 2.2
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