Selco Genesis 90, Repair Manual

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Unless specified otherwise, all the measurements must be taken with the boards fitted, together with their connections!
10) DESCRIPTION, TESTING AND REPLACEMENT OF THE ELECTRONIC BOARDS, CURRENT CALIBRATION
Introduction
Malfunctioning of a machine can be due to various causes.
Firstly you should check that the machine has been correctly installed and connected to the power supply (use of motor genera-
tor, extensions, plugs, presence of other large-size equipment that can interfere with the electrical power supply, etc.).
Secondly, you should check correct use of the power source according to the type and whether the problem could be due to causes
outside the power source (gas, pressure reducers, torches, expendable materials, earth clamps, welding cables, remote controls etc.).
You should then assess whether the problem could be due to incorrect setting of the welding parameters.
Only after you have carried out the above checks should you look at the power source itself, opening the covers and performing
an initial visual inspection. If necessary, carry out routine maintenance (blow-clean the power source).
Sometimes a fault in a machine can be due to loose contacts in the wiring and in the internal connections and these should the-
refore be inspected, at least visually.
In other cases the problem may be due to a faulty electronic board.
To speed up troubleshooting and optimise repair times, you are advised to proceed as follows:
1. visual inspection and checking of connections
2. with the machine switched off: instrumental check on power parts and any boards that may be faulty; if faults are found, repla-
ce the parts with equivalent spares (be careful of any configurations/calibrations to be performed on multi-purpose spares);
instrumental re-check with the machine switched off
3. with the machine on: instrumental check on power parts and any parts that have been replaced
4. power source test to check that the fault is no longer present
5. if an electronic board has been replaced, it may be advisable to perform the following check:
remove the board you have just fitted and replace it with the board previously removed, then re-test the machine to check
that the fault re-appears:
- if the original problem does not reappear when the original board is re-installed, then the problem is not due to that
board and you must continue the troubleshooting procedure;
- if the original problem re-appears, then the fault is due to that board; re-install the spare part and perform a final test on
the power source.
Caution! Performance of the check in point 5 above requires particular care and is not necessary when the board
shows signs of burning or evident faults (in this case re-installation of the faulty board can cause further damage
to the remaining parts of the power source).
In accordance with the above procedure, the following sections illustrate the normal working conditions of the power source
boards and provide the standard electrical values at the main points of the boards, both with the machine off and with the machi-
ne on.
All the measurements indicated can be performed with a digital multimeter.
26 Description, testing and replacement of the electronic boards, current calibration