5700A/5720A Series II Calibrator
Service Manual
5-48
1 V
10 ms
F5-6.EPS
Figure 5-6. Waveform at Pin 11 of K2
4. Check the 220 µA range of the 220 µA/2.2 mA AMP circuit. Set the Calibrator to
200 µA, standby. Set the external ac reference to 6.4V(±0.1V) at 1 kHz. Using a
DMM, measure the ac voltage at the collector of Q4 and verify it is 2.0V ac ±10%. If
a failure is detected, first verify that the 10 kΩ shunt on HR2 is correct and that it is
connected to SCOM thought relays K5C, K5D, K10, K13 and the 1.2Ω load resistor
R14 as in Figure 5-8. If the shunt and output switching is correct check Q4, Q5, K3,
and the associated components in the 220 µA/2.2 mA AMP circuit.