.:')eellon
v
k. Observe 652A monitor indication; if more than
± 0.2% from zero reference, change value of A3Rl *
slightly. Increase the value of A3Rl * if the monitor
indication is more than
+
0.2%; decrease · the value of
A3Rl * if the monitor indication is more than - 0.2%.
5-44. After Calibration.
5-45. After completing the ADJUSTMENT AND CALi
BRATION PROCEDURE, repeat PERFORMANCE TESTS
(paragraphs 5-7 through 5-20) to assure that the 652A is
within specifications listed in Table 1 - 1 .
5-46. TROUBLESHOOTING PROCEOURE.
SA7. Th.is section contains information and procedures
designed to aid in the process of isolating malfunctions.
Troubleshooting should be undertaken only after it has
been determined that the malfunction cannot be corrected
by performing the adjustment and calibration procedures.
5A8. \Vhen a malfunction occurs, first ensure that the
trouble is not caused by conditions external to the
lVlOUCI
0:) LA.
instrument, then make the front panel tests shown in Table
5- 8. These tests assume that the LiNE ON lamp is glowing.
If the symptoms outlined are observed, troubleshoot the
area indicated; refer to the Troubleshooting Tree (Figure
5- 1 1 ) and to Paragraph 5-52 for additional information .
5-49. The Troubleshooting Tree in Figure 5 - 1 1 illustrates a
systematic method of elimination used to locate a faulty
circuit or component. The tree does not include specific
troubles and problems; it presents a list of key pOints to be
checked for normal circuit indications or conditions, which
can be used to eliminate the properly operating circuits
from the troubleshooting path. The tests outlined in the
troubleshooting tree were not devised to measure all circuit
parameters, but to localize the malfunction. Therefore,
additional checks and measurements (including visual
inspection) will probably be required to completely isolate
the faulty component.
5-50. The Block Diagram (Figure 6-1) shows that the
instrument can be considered as five basic blocks; the
Oscillator Circuit, the Power Amplifier, the Normal Moni
tor Circuit, the Expand Monitor Circuit and the Regulated
Table 5-8. Front Panel Troubleshooting Tests.
(Set Output Monitor to Normal, Amplitude fully clockwise)
OPERATION
I . Switch OUTPUT ATTENUATOR
through all positions
2. Sweep FREQUENCY dial slowly
over its whole range for each
position of FREQUENCY
RANGE switch
3. Observe Monitor in both NORMAL
and EXPAND positions of the
OUTPUT MONITOR switch
(Signal must be present at the
50 ohm and 600 ohm jacks.)
4. Other troubles
5-1 6
SYMPTOM
No output at any position of
attenuator switch, monitor
indicates.
a.
Output only on XIOOK and
X I M ranges.
b. No output on any one range.
c. Output dies at one position of
the dial on all ranges.
d. Output twice normal level.
e. No output or monitor indication
on any range or dial setting.
a. No indication in NORMAL
mode only.
b. No indication in EXPAND
mode only.
c. No indication in both modes.
a. Dial Accuracy out of spec and/or
flatness out of spec
b. Incorrect meter indication
(particularly at high frequencies)
PROBABLE TROUBLE AREA
Output Attenuator or A2C22
a. A2QI
b. FREQUENCY RANGE switch
and associated components for
that range ;
frequency calibration:
c. Tuner capacitor (CI ) , shorting
or frequency calibration.
d. Peak Detector circuit (A2Q7)open.
e. Proceed to troubleshooting tree.
a. Normal monitor circuit (AI),
A2R41 or A2C25*.
b. Expand monitor circuit (A3).
M l or S4.
a. Frequency calibration, Peak
Detector A2Q7 ot A2CR6 and
A2CR7.
b. Monitor calibration.
