Keithley 610C, Инструкция по эксплуатации

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Ql03 and Ql04. Check Ql03 and Ql04 by removing
them and adjusting again for null. If null is no�
reached, replace the transistor pair �ith a new pair.
3. Check the next stage by connecting the Model
153 across the emitters of Ql03 and Ql04 and adjust­
ing the COARSE and MEDIUM ZERO Controls for null.
If null is not reached, check this stage and the
base circuit of the next stage.
Check the base cir­
cuit by removing transistors Q105 and Ql06 and again
adjusting for null. If null is now reached. replace
the transistor pair �ith a new pair.
4. Check the next stage by connecting Model 153
across the collectors of QlOs and Ql06 and adjusting
the COARSE and MEDIUM ZERO Controls for null. If
null is not reached, check this stage and check for
shorts in the base circuit of Ql07 and Ql08.
5. Connect Model 153 to the collector of Q109.
Adjust the FINE ZERO Control for null. If null is
reached, the dc amplifier is operating correctly and
the trouble is in output stage or the feedback stage.
6. Check the output stage, resistors R155 through
R158 and capacitor Cl16 for possible shorts.
7. The feedback loop includes the multiplier re­
sistors, R165 through R17s. the recorder output re­
sistors, R178 on 3V position or R176 and R177 on 1
MA
position, and the meter. An opening of any of
these components prevents zeroing of the meter. An
open multiplier resistor, however, prevents zeroing
for only that particular muitiplier setting.
FIGURE 13. Chassis, Side View.
17
15