Now place the mounting bush into the hole of the power device, with the flange of the bush lying on
the top side of the device. Take one of the insulating pads and place it against the rear of the
regulator. It should fit flat against the device and the bush should stick out a little allowing you to
align the pad correctly.
Now place the power device, bush and pad, flat against the rear of the panel so that the bush fits into
the panel hole. Make sure the pad does not slip out of place when you do this. Insert a 10mm M3
screw into the hole from the reverse side of the panel, and fit a spring washer and nut onto the screw
but do not tighten. Do the same for the other regulator making sure, of course, that the correct
device is in its proper location.
If you have drilled your holes correctly, you should find that the when the power supply PCB is
lowered back its four mounting screws, you can coax the power devices’ legs through the respective
solder pads on the board. Now tighten the four nuts holding the RPSU board in place. You should
have a flat washer and shakeproof washer under each nut. Gently tighten the screws holding the
power devices. Do not tighten them too much as this will crush the insulating pad. Once secured
you can solder the regulators' leads from the top side of the board and clip off any excess lead
lengths.
If the bottom panel of your case, or the power device's mounting tab, is too thin, you may find that
the insulating bushes are too long to allow the use of countersink screws. Countersink screws are
often better since they sit flush with the underside of the rack case. However, if the insulating bush
protrudes too far into the hole it may not allow a countersink screw to seat properly. Tightening the
screw will then inevitably crack the insulating bush and possibly allow the screw to make contact
with the power device's metal tab. In this scenario it may be better to use standard pan head screws
with no countersunk holes and accept that they stick out a little from the underside of the case.
Alternatively, you could use a 1.5mm or 2mm thick aluminium shim plate to go between the case
panel and the power devices. The size of such a plate is not crucial but 30mm by 60mm would be
appropriate. A Scheaffer fpd file can be found for such a shim plate on the project webpage.
Using an aluminium shim beneath the power devices so that the long part of the insulating bushes will not be
damaged by using countersunk mounting screws.