Telwin Tecnica 150 Troubleshooting And Repair Manual Download Page 13

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gate, also of Q1. The earth connections are both made to the
emitter of Q1.
E) Make sure the waveform displayed on the oscilloscope
resembles

H) Make sure the waveform displayed on the oscilloscope
resembles

and that the output voltage over OUT+ and

OUT - is equal to +80Vdc±10%.

I) 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 D14 is off,

If the

machine remains in alarm status (and this is not due to a fault
in the control board) there could be a fault in the photocoupler
ISO1 (

In this case the tests are just the same and can be carried out
with either a 115V or 230V power supply:
-

with a power supply of 115V±15% (LED D13 on and
orange) the voltage change board enables voltage
duplication by the input filter.

with a power supply of 230V±15% (LED D13 on and

green) the voltage change board disables voltage
duplication by the input filter.

The intermediate band with a power supply between

115V±15% and 230V±15% will be considered incompatible
so the machine will show alarm status (yellow LED D14 lit up).

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);

undo the 3 screws fastening the board to the bottom (

);

The 4 IGBT's are attached to 2 different dissipators and

whenever a replacement is required, both IGBT's should be
all replaced.

undo the screws attaching the dissipator to the board to
replace Q1, Q3 (

);

undo the screws attaching the dissipator to the board to
replace Q2, Q4 (

);

remove the 4 IGBT's and the 2 diodes D40, D41 by
unsoldering the rheofores and then clean the solder from
the printed circuit bump contacts;

remove the 2 dissipators from the board;

undo the screws locking the 4 IGBT's.

Before making the replacement make sure the components
piloting the IGBT's are not also damaged:
-

with the multimeter set in

mode make sure there is no

short circuit on the PCB between the 1 and 3 bump
contacts (between gate and emitter) corresponding to
each component;

alternatively, resistors R40, R41, R42, R43 could have
burst and/or diodes D32, D33, D34 and D35 may be
unable to function at the correct Zener voltage (this should
have shown up in the preliminary tests);

clean any irregularity or dirt from the dissipators. If the
IGBT's have burst the dissipators may have been
irreversibly damaged: in this case they should be
replaced;

apply thermo-conductive grease following the general

fig. B.

fig. C

fig. 3

N.B.

fig. 3

NOTE:

fig. 1

fig.

A) Please read the procedure for replacing the IGBT's
carefully: (fig. 4).

fig. 2B

ohm

Set up the dual trace oscilloscope. Connect probe CH1

(x100) to the collector of Q1 and probe CH2 (x10) to pin 9 on strip
J11. The earth terminals are connected together to the emitter of
Q1.

6.3 Tests for the TECNICA 161

7.1 Removing the power board fig. 2A

(

)

Repeat this test also for Q2, Q3. Q4 (for Q3 and Q4 use the

differential probe).

if the signal is not present there could be a fault in the

IGBT driver circuit (

) or in the control board (

this case we recommend replacing the board).

N.B.

fig. 3

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.

remove the board from the metal structure, lifting it
upwards.

for assembly proceed in the reverse order and

remember to insert the toothed washer on the earth screw.

Warning:

N.B.

- 13 -

SETTINGS:

PROBE

TIME TOLLERANCES
±20%.

AMPLITUDE ON CH1
IS

AMPLITUDE ON

CH1 x100;