Service manual

Principles of Operation
Error amplifier AMP3 operates as follows. The negative terminal of AMP 3
receives Vref (5 V) and the voltage applied to the positive terminal is adjusted to
5 V. As shown in Figure 2-22, the output voltage is:
~(Rl14+R115) =
2 4z Jhms (9.1 K ohms + 2.4K ohms) = 23.96 V
Figure 2-22. Constant Voltage Control (+24 KDC)
AMP 2 controls over current as follows.
+24 V is applied to the negative terminal.
The positive terminal receives an equal voltage when a negative current of the
following value flows:
OutPit ylltage R 124/Rl27 =
+24 ’
11K ohms
560 ohms / 0.22 ohms =5.55 A
2-22
LQ-200/AP3000