Ap1:6 Shunt And Current Control Amplifier - ESAB Caddyt Arc 150i Service Manual

Version 2 of circuit board 20AP1
15ST2, which is fitted on the heat sink, opens at 85 _C. 15ST1, which is fitted
in the winding of the main transformer, 15TM1, opens at 130 _C.
If either of the switches operates, the power source is stopped, a fault code is
displayed and the temperature indication LED on the control panel lights.
Circuit board version 1 displays fault code E13.
Circuit board version 2 displays fault code E06.
The power source cannot be restarted until it has cooled sufficiently for the
switch(es) to reclose.
The state of the thermal switches and the overload indication can be tested by
service functions, see pages 38 to 43.
Version 1 of circuit board 20AP1: Sometimes the temperature indication LED
may gleam weak when it is off, this is no fault. When the LED is activated, it
lights with a clear light at the same time as the fault code is displayed.
20AP1:6 Shunt and current control amplifier
The shunt produces 60 mV at a welding current of 100 A. The shunt response
is linear to the welding current.
If the shunt is not connected to the circuit board, resistor R2 supplies about
1.4 to 1.9 V to the shunt input. This blocks the current control amplifier, i.e. the
machine does not deliver any welding current.
S0740 800 161/E061205/P66
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