ESAB Origo Arc 410c, Service Manual

Page: 16 / 40

15
CH21 Control circuit board
Welding current setting circuit
Reference voltage of 5.1V from the A2 integrated circuit is the source of the reference voltage for the
setting circuit. In order to obtain the reference voltage required for setting the current – the 5.1V
voltage is separated in the follower circuit consisting of the following elements: A13a, R
137
, C
51
and
R
138
.The R01 local setting potentiometer is connected in parallel to the C
51
capacitor. The voltage of
+10V on the A13b operational amplifier output is the reference voltage for the remote wire current
setting in this circuit. The system of three keys of the A17 integrated system makes up an electronic
switch which switches on the remote or local welding current setting. When the local setting is on, the
welding current setting signal is transmitted from the R01 potentiometer slide via the R
142
resistor and
the shorted A17c key onto the input of the separating follower, made on the A13d operating amplifier.