Velleman K4020 Mode D'emploi page 29

ASSEMBLY ON THE HEAT SINK (procedure for each heat sink)
Mount the three brackets on the pcb as illustrated in Figures 1.0 and 1.1
Position the pcb against the heat sink and mark the centres of the transistors
(T10-T13) and of the thermal switch TS using a pencil. Also mark the position
of bridge rectifier B1 (see Fig. 1.2 for the left hand amplifier and Fig. 1.3 for the
right hand amplifier).
ATTENTION: Watch the alignment of the print edge with the heat sink edge!
Mounting the MOSFET transistors T10 to T13:
Insert four M3 hexagon bolts into the mounting slot of the heat sink and
position them on the marked positions for the transistors (see Fig. 2.0).
Glue the mica insulating plates in the position of the transistors using a little
thermally conductive silicone compound (available from specialized shops).
IMPORTANT: Do NOT use any rubber silicone insulating plates!
Bend the connections of the power transistors as in Fig. 2.1.
Put some thermally conductive compound on the metal back of each transistor
and mount them using a washer, lock washer and M3 nut in the following
positions: (see also Fig. 2.1 and 1.2 or 1.3)
T10 and T11: type IRFP9140 (left on the heat sink)
T12 and T13: type IRFP140 (right on the heat sink)
Using an ohmmeter check whether the centre connection (DRAIN) of the
transistors is not connected to the heat sink (For a proper contact with the
measuring pin the paint may be removed slightly from the inside of the heat
sink).
Mounting the thermal switch TS (see Fig. 2.2):
The thermal switch is mounted as the MOSFET transistors, but without
insulator.
Mounting the bridge rectifier B1:
Insert a hexagon bolt in the mounting slot of the heat sink, in the position of the
rectifier.
Mount the bridge rectifier on the heat sink using a washer, lock washer and M3
nut (see Fig. 3.2).
NOTE: Mount the bridge rectifier in such a way that the "+" identification on the
side can be read.
Mounting the prints onto the heat sinks:
Together with a washer and lock washer, mount a 10mm M4 bolt and nut on
each bracket.
Slide the print and bracket assembly in the slot in the heat sink (see Fig. 3.0),
up to the position where the connection with the transistors should be made.
Tighten the three bolts securely. Repeat this procedure for the other print and
heat sink.
H4020-ED2-29