Rev 1.03
13
Note that this does NOT necessarily check that you correctly orientated the windings. The only
way to do that, was with the DVM continuity check before inserting the transformer; and after
identifying the windings, being careful not to mix the wires again while inserting the transformer in
the PCB; finally checking again once the wires are inserted but before soldering.
3.5
Install heatsink assembly
In this kit the IRF510 transistor final (Q7) is fitted to
the metal heatsink. The metal tab of this transistor
must not short to ground or to other parts of the
circuit. Therefore insulating silicone rubber pads
are used, and insulating white plastic washers. In
this photo (right) the heatsink is viewed side-on
before assembly. The picture shows how the
transistor assembly must be put together before
soldering.
On the side of the heatsink with the large gap, the
silicone pad is placed on the heatsink where the
IRF510 transistor will sit. The transistor is placed
on the silicone pad. The white nylon insulating
washer is pushed into the hole in the transistor tab. The bolt then fits
through the hole. The metal bolt does not touch the metal tab of the
transistor, and the tab does not touch the heatsink.
In the prototypes I put the bolt on the far side and the nut on the
IRF510 side, as shown. Then it is easiest to grab the bolt with pliers
while tightening the screw from the other side.
If you have some heatsink compound then this would be a good idea
(though the prototypes development and testing did not use it). Take
care to align the transistor accurately and tighten the bolt/nut well.
You will be rewarded by an assembly which fits easily into the holes
on the PCB.
