Ap1:3 Remote Control Input - ESAB Caddyt Arc 150i Service Manual

20AP1:3 Remote control input
If the remote control input is activated, but there is no reference signal, resistor
R54 holds the reference input low. This results in a welding current of 3 A for
TIG welding and 4 A for MMA welding. The remote control input can be tested
by a service function:
Circuit board version 1, see service function no. 22 on page 39.
Circuit board version 2, see service function no. 16 on page 42.
20AP1:4 Pulse width modulator
The pulse width modulator determines the frequency and pulse time of the
switching transistors' control pulses. IC3 controls the pulse frequency, the
pulse time and inhibition of pulses.
The pulse frequency is 65 kHz +/-- 1kHz, with a maximum pulse width of 43 --
44 % of the cycle width. See page 49 for screen traces of waveforms and
measurement instructions.
Transistor Q5 controls the primary winding of the pulse transformer on circuit
board 15AP1.
20AP1:5 Temperature monitoring
Version 1 of circuit board 20AP1
The thermal overload switches, 15ST1 and 15ST2, are normally closed.
Terminal T2 of circuit board version 1 is at 10 V.
Terminal T2 of circuit board version 2 is at 0 V.
ct27d_20
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S0740 800 161/E061205/P66