6.3 Scheduled tests for theTECNICA 114 (230V)
6.4 Scheduled tests for theTECNICA 114 (115V)
7.1 Removing the power board (fig. 2A)
A) Disconnect the stabilised power supply from the power
board.
B) Set up the dual trace oscilloscope. Connect probe CH2
(x100) to the collector of Q1 and probe CH1 (x10) to the
gate, also of Q1. The earth terminals are connected
together to the emitter of Q1.
C) Connect the power supply cable to a
single phase
variac with variable output 0-300 Vac.
D) Switch on the variac (initially set to 0V), close the main
power supply switch on the power source and gradually
increase the voltage generated by the variac until it reaches
230Vac then make sure that:
-
the green power supply LED D34 lights up (
);
-
the fan starts to turn for the power transformer;
-
pre-charge relay K1 closes (
);
-
for voltages close to the rated power supply value
(230Vac ±15%) the power source does not signal an
alarm (yellow LED D35 off).
if the alarm persists in the power source this could be
due to a fault in the control components (in any case
proceed to make further tests).
E) Make sure the waveform shown on the oscilloscope
resembles
.
if the signal is not present it may be
necessary to replace component Q1 or, alternatively, the
driver circuit U3, Q6 and Q7 (
).
F) Set up a multimeter in volt mode and make sure that (
):
-
the voltage over pins 2 and 1 of J8 is equal to +23Vdc
±5%;
-
the voltage over pins 5 and 1 of J8 is equal to +5Vdc
±5%;
-
the voltage over pins 4 and 1 of J8 is equal to +500mVdc
±5%;
-
the voltage over pins 8 and 1 of J8 is equal to 0Vdc;
-
the output voltage over OUT+ and OUT- is equal to
+80Vdc ±10%.
G) Set up the dual trace oscilloscope. Connect the voltage
probe x100 between the gate of Q1 and the earth to the
emitter, also of Q1 (
). Probe CH2 (x10) to the rheofore
of R55 towards C11 and the earth to the anode of D11.
H) Make sure the waveform shown on the oscilloscope
resembles
.
I) Switch the power source off and on again and make sure
that, after the transitory switch-on time, there is no alarm
(yellow alarm LED D12 is off
)
If an alarm persists
(and is not caused by a fault in the control board) there could
be a fault in the opto-coupler ISO1 (
).
Power the power source at the rated voltage of
115Vac. In this case the tests are exactly the same as those
for the Tecnica 114 (230V) 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.
fig. 3
fig. 3
N.B.
fig. B N.B.
fig. 3
fig.
3
fig. 3
fig. C
fig. 3 . N.B.
fig. 3
WARNING!
fig. 1
fig. 2B
fig.
2B
fig. 2B
N.B.
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:
- 12 -
TECNICA 114
FIGURE B
SETTINGS :
· PROBE CH1 x10;
· 10 V/Div;
· PROBE CH2 x100;
· 200 V/Div;
· 5 sec/Div.
TIME TOLLERANCES:
±20%.
· AMPLITUDE CH2
IS 320V ±10%;
· POSITIVE
AMPLITUDE CH1
IS +18V ±10%;
· NEGATIVE
AMPLITUDE CH1
IS -10V ±10%.
µ
VERIFY THAT
FIGURE C
SETTINGS:
· PROBE CH1 x100;
· 200V/Div;
· PROBE CH2 x10;
· 500mV/Div;
· 5 sec/Div.
TIME TOLLERANCES:
±20%.
· AMPLITUDE CH1 IS
640V ±10%;
· AMPLITUDE CH2 IS
500mV ±50%;
µ
VERIFY THAT
