Section V Model 3300A
jumper location). If 3300A operation is normal with this
plug mated with J6, the trouble is in the plug-in unit.
Figure 5-7. Malfunction Isolating Plug
5-56. PRECAUTIONS.
5-57. In the event the -20 volt supply is inoperative, the
oven heater should be disabled while troubleshooting. A
point to disable the oven is to disconnect the smaller
diameter red wire (26 gage) from XA12 Pin 1. The larger
diameter redwire (22 gage) should be left connected to
XA12 Pin 1. When the -20 volt power supply is left out,
the oven remains in full heat condition. Thermal fuse
A11F1 will melt and open if this heat condition exists for
any extended period.
5-58. When troubleshooting Power Supply Assembly,
remove the Output Amplifier Assemblies A15 and A16.
5-59. TROUBLESHOOTING TREE.
5-60. In the event of a malfunction which causes the
oscillatory system to cease functioning; the output of the
triangle integrator emitter follower would most likely
stabilize at either one of voltages as indicated in Figure
5-8. Approximately +25 volts is the upper limit of the
positive slope, and -2.5 volts is the lower
Table 5-4. Troubleshooting Aid
SYMPTOM POSSIBLE CAUSE
No output either channel. Power Lamp lit. Use Figure 5-8 Troubleshooting Tree.
Output on only one channel. Check applicable amplifier board A15
CHANNEL A or A16 CHANNEL B.
Frequency incorrect. Specific range. Check feedback capacitor of effected
range on Triangle Integrator A12; for
example, Range X100 check C10, C11,
and C12.
Two of the three functions normal, only Check input resistor of missing function;
one channel effected. on amplifier assembly; for example, no
SINE on CHANNEL A. Check A15R1.
Frequency and symmetry incorrect at Check oven heating voltage J6 pin 42
low end of dial, all ranges. 20 volts.
Frequency will not vary with FREQ dial. Check Freq shorting bar rear chassis;
A11Q5 and associated circuit parameters.
No sync output. Check A14C7, A14R46 and A14R48.
Power supply voltage incorrect. Begin troubleshooting by substituting a
well-regulated 12.1 volt source for A11CR1.
Remove Output Amplifiers when trouble-
shooting Power Supply.
Frequency out of tolerance on 1 or 2 Change A11Q8. Use caution in soldering
ranges which are not adjacent. and use a clip-on heat sink.
Distortion at 100 kHz. Check A13Q1.
Dc level off on square wave. Check A14CR18 for open.
Symmetry erratic at low frequencies. Check A14Q8.
Lower half of sine wave clipped on one Check A15Q5 or A16Q5.
channel only.
Will not oscillate. Check Triangle Integrator A13Q1 thru
A13Q3.
5-8
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