ESAB LAW 510 Service Manual page 20

3
MACHINE TYPE / TEST INPUT
J3 and J4 must be linked in the LAW 500/510: if the link is removed, the machine
will operate as an LAW 400. But never link J3 and J4 in an LAW 400/410.
Test input
Use the test inputs to test the performance of several input and output signals on the
circuit board. See the description on page 31.
4
FIXED / CONTROLLED FIRING ANGLE
When K2 and K3 are linked, the machine operates with a fixed thyristor firing
angle. When K1 and K2 are linked, the machine operates with a controlled
(variable) thyristor firing angle.
A fixed thyristor firing angle means that the thyristor output is affected only by the
setting of the voltage control potentiometer.
A controlled (variable) thyristor firing angle means that the thyristor output is also
affected by the actual value of the arc voltage (arc voltage control). This means that
the machine compensates for variations in mains supply voltage.
It is only possible to change between controlled and fixed thyristor firing angle
when the machine is switched off.
Circuit board 0486 220 880 must be used only with fixed thyristor firing angle.
Circuit boards 0486 291 880 and 0486 480 880 are to be used with controlled
thyristor firing angle.
LAW machines with serial numbers of 512 . . . . . . . and above are supplied with
controlled thyristor firing angle.
For machines with circuit board 0486 220 880 there is an exchange circuit board
with controlled thyristor firing angle.
The ordering number for the exchange board is: E486 220 882.
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