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Model 5065A
Circuit Diagrams, Theory, and Maintenance
A7 Test Setup
HP204C
osc
I37HZ
IOM
- W V -
L
I
MOUNTED
IN A
SHIELDED
CAN
A7JI
3)
Connect oscilloscope to A7TP2.
Output
should be about 1V peak-to-peak.
4)
Connect oscilloscope to A7TP1.
Signal
should be about 0.5 V peak-to-peak.
5)
Connect oscilloscope to A7 output (yellow
lead). Signal gain at this point with respect
to the signal level at A7TP1 can be varied
from zero to approximately 100 by R32. With
R32 set for proper loop gain, the A7 output
signal will be roughly 10 to 40 times the sig
nal atA7TP1.
7)
Remove the test setup and oscilloscope con
nections. Using the Micon-to-BNC test cable
provided, connect a dc voltmeter to A7J1.
DC voltage at this point should not exceed
±5 mV.
Excessive dc voltage at this point
will result in a noisy solar cell (A12 RVFR
Assembly) output. Adjust A7R3 to bring this
voltage below ±5 mV if required.
8)
Remove test cable and dc voltmeter. Recon
nect cable from A12 Assembly to A7J1.
TROUBLESHOOTING AND REPAIR
a.
If any components in the preamplifier circuit
are replaced, connect a voltmeter to A7Q1 base and
adjust A7R3 for less than 0.5 mV at this point.
b. After
any
repairs to A7 Assembly,
adjust
A7R32 as described in Section 5-30, LOOP GAIN
ADJUSTMENT.
MODULE REPLACEMENT
6)
Set CIRCUIT CHECK meter switch to 2ND
HARMONIC.
Reduce oscillator output and
allowing for a time lag, note the CIRCUIT
CHECK meter response.
Meter should fol
low oscillator level setting.
This procedure
checks the second harmonic detector circuit
of the A7 Assembly.
If the A7 Assembly is replaced with either a repaired
or new Assembly, set A7R3 as described in the pre-
ceeding section TROUBLESHOOTING AND REPAIR.
Also A7R32, the loop gain adjustment, should be ad
justed as described in Section 5-30, LOOP GAIN
ADJUSTMENT. Perform adjustments outlined in Para
graphs 5-27 to 5-31.
7-31
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