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MAINTENANCE
MODEL 148 NANOVOLTMETER
NOTE
If
transistors
42.1, 922 or Q23 are replaced,
it my be necessary
to
change resistor
R307.
A 27-kilohm
resistor
should provide
the proper
bias
for 422 and 423.
The wave form at point
F should resemble Figure
16.
If it
does not but resembles
Figure
17, use a 15-kilohm
resistor
for R307.
Fl
in Oscillator
Circui:t.
2 msec/cm horizontal.
Scale is 2 v/cm &rtIcal,
FIGURE 17.
Improper
Wave Forms at Point
F (Figure
21) in Oscillator
Circuit.
Wave A indicates
the wrong bias;
wave B is distorted.
Scale for both is 2 v/cm
vertical,
2 mseclcm horizontal.
32
0664
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