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these features, you have to remove that ring, turn the switch completely to the left (into
position 1), and reinstall the ring with the tab in position 2. Check if the switch
effectively has only two positions now.
Now fix the switch onto the pcb, with its spindle at the solder side. See that the
centring pin comes in the right hole!
Connect pins 1 through 8 to the points with the same name on the pcb, using
unisolated wires. Connect points A and B with the pcb, using isolated wires.
Connections 9 through 12 and C are not used.
•
Solder three pieces of isolated wire (length about 3 cm) to the headphone connections
(HPR, HPL, and ground).
•
Insert the IC's into their sockets:
•
IC1 and IC2, TL074 or equivalent, with their notch towards the voltage regulators.
•
Before you start mounting, first read the following tips.
TIPS FOR THE HOUSING.
Some demands are made upon the housing of a mixing panel: not only to keep the thing
esthetically justified, but above all because the technical qualities of the circuit should not
be degraded.
Since the inputs usually are very sensitive (microphone, record player...), you must take
care that as little noise as possible is allowed to penetrate. Therefore a metal housing is
indispensable. But also within the housing we have to be careful: the transformer, and
the wiring of the primary circuit can be an important source of noise. Therefore it is no
luxury to separate the complete power supply (mains cable, mains fuse, switch,
transformer and power supply module) from the rest of the circuit, using a metal partition.
Only the DC-outputs of the power supply module go through an opening in the partition
to the mastermodule.
Figures 4 and 5 show how the modules have to be placed in order to reduce wiring to a
minimum. Attention: all drawings of the frontplate are in front view, seen from the outside!
All modules, and the transformer, are fixed to the front plate, using bolts with
countersunk heads.
Except the big VU-meter, all modules have their solder side towards the front plate.
When using the separately available plastic upper layer, it is better to use the enclosed
large drilling stencil. The upper layer may not be sticked until the front plate is completely
finished, this means, all the holes drilled, slantingly milled out where necessary, and all
fixing bolts fitted and fixed using a nut or screw bush. Carefully read the explanation
enclosed with the upper layer! When you are not good in drilling, sawing and filing, you
can use the separately available ready frontplates.
Stick the upper layer before you start mounting the modules, because otherwise the
switches and potentiometer spindles will make good work impossible.
See that ALL the holes for ALL the modules are drilled before you start mounting.
Don't forget the connectors for the in- and outputs!
There is enough room on the back of the housing for all inputs. The outputs can be
placed at choice on the side or the back of the housing. When placing the outputs on the
back, the housing must be high enough, in order to have enough room for the output
connectors under the power supply compartment!
Pay attention to earth loops: connectors whose ground connection would make contact
with the metal housing (like e.g. 6.3mm jacks and cinch models) have to be isolated,
