Selco Genesis 240 TLH, Repair Manual

Page: 16 / 82

98 Description of machine operation
The connector for connection of the RC16 and RC12 remote
controls is also provided.
For operation in MMA, see previous directions.
With the selector set to TIG H.F., operation is as follows.
With the selector set to TIG 2-strokes, the sequence is as fol-
lows:
• 1st stroke - Torch button pressed: opening of gas solenoid
valve and, after a settable pre-gas time, triggering of H.F. (if
the arc is not sparked, the H.F. is maintained for approxima-
tely 1.5 sec) and power command (possible slope-up).
• 2nd stroke - Torch button released: current descent ramp
followed by inverter switch-off while the solenoid valve is
kept open for a variable time (post-gas time).
With the selector set to TIG 4-strokes, we have the following
sequence:
• 1st stroke - Torch button pressed: gas solenoid valve opens.
• 2nd stroke - Torch button released: H.F. triggered (if the arc is
not sparked, the H.F. is maintained for approximately 1.5
sec.) and power command (possible slope-up).
• 3rd stroke - Torch button pressed: current descent ramp fol-
lowed by inverter switch-off while the solenoid valve is kept
open.
• 4th stroke - Torch button released: the solenoid valve is kept
open for a variable time (post-gas time).
With the selector set to TIG bilevel the sequence is as follows:
• 1st stroke - Torch button pressed: opening of gas solenoid
valve and, after a settable pre-gas time, triggering of H.F. (if
the arc is not sparked, the H.F. is maintained for approxima-
tely 1.5 sec) and power command with welding current level
equal to initial current (= % of welding current).
• 2nd stroke - Torch button released: welding current level
equal to level set I (possible slope-up).
• Bilevel - Torch button pressed and immediately released: wel-
ding current level equal to I2 (without slope).
• Bilevel - Torch button pressed and immediately released: wel-
ding current level equal to I (without slope).
• .
• 3rd stroke - Torch button pressed: current slope down. At the
end of slope down, the current is maintained equal to the
final current If.
• 4th stroke - Torch button released: the inverter switches off
and the solenoid valve is kept open for a variable time (post-
gas time).
With the selector set to TIG LIFT, operation is the same as TIG
H.F. with the following variations in the initial triggering phase.
With the selector set to TIG 2-strokes:
• 1st stroke - Torch button pressed and torch in contact with piece:
opening of gas solenoid valve and, after a settable pre-gas time,
power command with current limited to approximately 30A (the
current reaches the set level when the electrode is lifted).
With the selector set to TIG 4-strokes:
• 1st stroke - Torch button pressed and torch in contact with
piece: opening of gas solenoid valve.
• 2nd stroke - Torch button released: power command with
current limited to approximately 30A (the current reaches the
set level, possibly with slope up, when the electrode is lifted).
With the selector set to TIG bilevel the sequence is as follows:
• 1st stroke - Torch button pressed and torch in contact with the
piece: opening of gas solenoid valve and, after a settable pre-gas
time, power command with current limited to approximately
30A.
When the torch is raised the welding current reaches the
initial current value (=% of welding current).
On board 15.14.236, but accessible only with the machine
open, there is also a welding current maximum calibration
potentiometer with reference provided by the remote control.
The torch button command arrives at the same board
(15.14.236). This command is electrically disconnected by relay
from the electronic control and adjustment circuits.
The board generates the following voltages inside (referring to
different grounds):
• +5 Vdc (command circuits power supply)
• +24 Vdc (torch button insulation relay power supply)
• +5 Vdc (remote controls RC12 and RC16 power supply)
converting the input voltages supplied by the auxiliary transformer (l):
• 9 Vac
• 24 Vac
It also receives the voltages (ground with same +5 Vdc power
supply as above command circuits) :
• +15 Vdc
• -15 Vdc
from board 15.14.254 .