Service manual

S0740 800 179/E071123/P64
-- 2 8 --
ct33_20
The voltage on terminal PS4 is normally about 24 V, when this drops below
20 V, pin 14 of IC6 goes low, providing the processor with a low power supply
voltage signal. The processor then stores current data and generates fault
code E4. When the 5 and 2.
5 V voltages are passing below their treshold
values, the processor receives a reset signal from IC16.
Fault code E4 is not displayed at normal power off
+15V and +20V
Voltage regulator VR2 produces an output voltage of +20 ±1.0 V, which
supplies the pulse width modulator output stage.
Potential divider R70/R75 supplies 2.6 V to the processor. This provides a
signal that the power supply is available.
Voltage regulator VR1 produces an output voltage of +15 V, and this, together
with the -- 15 V supply, powers the analogue circuits.
--15V
The --15 V power supply is monitored by the processor.
+12 V_CAN
The +13VB from 2AP1 is used to supply the CAN circuits of the equipment.
This supply is referred to as + 12V_CAN, its neutral point, 0V_CAN, is
separated from the electronic neutral (0 V).
The tolerance of the voltage is 11.5 to 14.5 V.