N.B.
fig. 3
volt
fig. 3
fig. 3
fig. B.
N.B.
fig. 4
fig. 3,
fig. C
fig. 3
N.B.
fig. 3
WARNING!
fig. 1
fig. 2B
fig.
2B
fig. 2B
N.B.
if no signal is present, it may be necessary to replace the
integrated circuit U2 (
).
D) With the multimeter set in
mode make sure that
(
):
-
the voltage between connector J9 (-) and the cathode of
diode D32 (+) is equal to +13V ± 5% (
);
-
the voltage between faston PT1 (-) and the cathode of
diode D30 (+) is equal to +12.5V ± 5%;
-
the voltage over the ends of capacitor C10 is equal to
+29V ±5%;
-
the voltage over the ends of capacitor C13 is equal to
+29V ±5%;
E) Set up the dual trace oscilloscope. Connect the probe
CH1(x100) to the Q1 collector and probe CH2(x10) to the
gate, also of Q1. The earth connections are both made to the
emitter of Q1.
F) Make sure that when the torch button is pressed the
waveform displayed on the oscilloscope resembles
G) Repeat this test on Q2 as well using the differential probe.
if the signal is not present, there may be a fault in the
IGBT driver circuit (
) or the plasma control board (
in the latter case, we recommend replacing the board).
H) Set up the dual trace oscilloscope. Connect the probe
CH1(x10) to pin 9 of J8 and the earth to connector J9.
Connect probe CH2(x100) to the Q1 collector and the earth to
the emitter, also of Q1.
I) Make sure that when the torch button is pressed the
waveform displayed on the oscilloscope resembles
and
that the output voltage over OUT and OUT + is equal to
750Vdc ±5%.
J) Switch the power source on again and make sure that,
following the brief start up time, the machine is not in alarm
status (the yellow alarm LED D26 is off,
).
K) Make sure that the solenoid valve is energised when the
torch button is pressed.
if the machine remains in alarm status (and this is not
due to a fault in the plasma control board) there could be a
fault in the photocoupler ISO1 (
).
Power the power source with a rated voltage of
115Vac. In this case the tests are just the same as for the
Tecnica Plasma 31 and can be carried out in the same way.
If the fault is in the power board remove it from the bottom as
follows:
-
with the machine disconnected from the main supply,
disconnect all the wiring connected to the board;
-
remove the current adjustment knob on the front panel of
the machine (
);
-
remove any bands constraining the board (e.g. on the
power supply cable and connections to primary);
-
from the welding side undo the two screws fastening the
dinse sockets to the printed circuit board (
).
-
undo the 2 screws fastening the board to the bottom (
).
-
undo the 2 screws fastening the board to the front and
back on the inside (
).
-
after removing the screws, lift the board upwards to
remove it from the bottom of the machine.
to re-assemble, proceed in the reverse order,
remembering to insert the toothed washers on the earth
screws.
6.3 Tests for the TECNICA PLASMA 18
7.1 Removing the power board fig. 2A
(
)
7.0 Repairs, replacing the boards
If repairing the board is complicated or impossible, it should
be completely replaced.
The board is identified by a 6-digit code (printed in white on
the component side after the initials TW). This is the reference
code for requesting a replacement: Telwin may supply boards
that are compatible but with different codes.
before inserting a new board check it carefully for
damage that may have occurred in transit. When we supply a
board it has already been tested and so if the fault is still
present after it has been replaced correctly, check the other
machine components. Unless specifically required by the
procedure, never alter the board trimmers.
WARNING!
SETTINGS
PROBE
· AMPLITUDE CH1:
· AMPLITUDE CH2:
:
· PROBE CH1 x10
· 500mV/Div;
·
CH2 x100;
· 100V/Div;
· 5 sec/Div.
TIME TOLLERANCES:
· ±20%.
VERIFY THAT:
0.8V ±10%.
320V ±10%..
µ
FIGURE C
- 13 -
TECNICA PLASMA 18 - 31
FIGURE A
SETTINGS CH1:
· PROBE x100;
· 100 V/Div;
· 10 sec/Div.
: 60KHz ±10%.
450V ±10%.
µ
VERIFY THAT
THE FREQUENCY
IS
·
· AMPLITUDE IS:
SETTINGS
TIME TOLLERANCES:
±20%.
· AMPLITUDE CH1
IS 320V ±10%;
· POSITIVE
AMPLITUDE CH2
IS +16V ±10%;
· NEGATIVE
AMPLITUDE CH2
IS -10V ±10%.
:
· PROBE CH1 x100;
· 100 V/Div;
· PROBE CH2 x10;
· 10V/Div;
· 5 sec/Div.
µ
VERIFY THAT
FIGURE B
