ESAB Caddy Tig 1500i TA34, Service Manual

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DESCRIPTION OF OPERATION
0740 800 186 - 29 - © ESAB AB 2016
Communication interruptions
If the CAN bus fails, the control panel will normally generate a fault message. Check the
following points in the event of problems with CAN communications:
• The terminating resistor. The CAN bus resistance must lie in the range 50-130 ohm: the
optimum value is 60 ohm. To check the resistance, turn off the power source and
measure the resistance between pins L and K in connector socket XS25.
• All screen connections must be sound. Check the screen connections of the CAN
cabling.
• Good contact with the chassis connections from/to the circuit boards and suppressor
capacitors. See the main circuit diagram.
• The connection cable between units. Check that the correct type of cable is being used.
Check that each signal is being carried by the correct core. CAN H and CAN L must be
carried by the twinned pair.
Terminating resistors
In order to avoid communication interference, the ends of the CAN bus must be terminated
by resistive loads.
20AP1:3 Control panel interface circuits
See the service manual for the TA33 and TA34 control panels, filename: 0740 800 180.
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.