Trigger Input
Period Generator
HP 8114A Service Guide
able
5-5.
Power Supply Voltages on the Timing Board
1.
Apply a 1 MHz squarewave signal with 5 V amplitude, 0 V offset
from a 50
0
source to the trigger input.
2. At the junction of R313, and R314, or at pin 7 of
U304
a typical
voltage should read 1.75
V.
3. Program + 10 V trigger input threshold in the
TRi!T;GEF:
mode
display.
4. Check that at
U302A
pin
1
there is a typical voltage of
t
3.3
V,
and
at
U304
pin 9 a typical voltage of + 1.7 V.
Check for the supply voltages:
1.
U407
pin 1 for + 12 V, and
1J407
pin 3 for + 5
V.
2.
U402
pin 2 for -12
V,
and
U402
pin 3 for -5.2 V.
Check the current sources for the period generator:
1. Check pin 3 of
U406,
voltage regulator, for
+
12 V.
2. Check pin 2 of
U406
for
+8
V.
3. Varying the frequency from 1.01 MHz to 10.0 MHz the voltage at
pin 1 of U404A should vary from -0.5 V to -5.0 V.
4. Check for the following voltage drops across R402:
‘Ihble
5-6. Voltage Drops Across R402
Delay Generator
Check for the supply voltages:
17502 pin 2 for -12 V, and U502 pin 3 for -5.2
V.
Check the current sources for the delay generator:
1. Varying the delay from 0.00 ns to 999 ns the voltage at pin 8 of
U504C
should vary as follows:
Troubleshooting 5.13
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