Filter
Top Products
With panel removed once again, you can now fit the switches. The C&K PCB mountable
switches should fit tightly into their respective holes on the board. Make sure the ‘on-off-on’
switch goes into the ‘filter control’ location. You may need to use a pair of fine nosed pliers to
help the flexible gold pins into the board holes.
Make sure the switch body is flat against the board. Now refit the front panel and make sure
the round switch barrel fits into its hole in the front panel. Now solder all the pins on the
switch including the securing pins to the front.
That completes the soldering of the front panel components.
Housing your unit
The PCB has been designed to fit into a standard 1u high 19” rack unit. Your local parts
distributor will have these. Good rack units are quite expensive, and will contribute heavily to
the final cost of your completed 3031. Expect to pay around £30 or so.
Your choice of case will also be affected by what else you want in your enclosure. In my
prototype, I also have the tbDAC and internal mains transformer. This would require a case
that is at least 25cm deep. If you are just fitting the 3031 PCB and a few sockets on the back,
you could get away with a smaller depth case.
If you find a good supplier of low depth 1u metal racks in the UK, I would be pleased to hear
from you. Maplin sell an excellent range of racks, but all of them are very deep. Bryant
Broadcast, Electrospeed and RS Electronics Ltd do have a range of rack units that may be
suitable.
The Bryant Broadcast ones are superbly made, but they do not allow you to use the 3mm
thick Scheaffer front panel. Their cases actually utilise the front panel as part of the enclosure.
Simply swapping the Bryant panel with one obtained from Schaeffer will not work. Of course,
if you are drilling out the Bryant panel to the Scheaffer plan, then this would indeed work
wonderfully. Bryant do custom metal work, so it may be possible to try their services. This is
one area I would like to try in the near future. Another option is to send the plain Bryant
Broadcasting front panel to Scheaffer for engraving. Contact Scheaffer for details of this
service.
If you buy the cases made by Vero from Farnell and others, you will find that the height of the
unit internally is quite restricting. The bottom and lower panels have 6mm folds in them at the
front. This effects the amount of space available for the pots and circuit board at the front
panel. It is possible to use these cases as I have done, but I needed to cut back the three pins
on each pot to prevent them shorting with the case. The pot bracket pins actually prevent the
case from then touching the pot’s pins. This is all right, but you need to allow a minimum of
0.5mm slack when you fit the front panel to the case.
The other thing to beware is the heatsinks. Don’t let either one of them touch the top panel, or
the top surface of the PCB since this would cause major problems. This shouldn’t happen if
you make sure the regulators ICs are fitted tight against the PCB.
18