
External Variable Range function. All of these options are found on page 9 of the front
panel/interconnect schematic. They all require the addition of an External Range Input
jack, which is also mentioned in the Analog Ground Strap section. One of them (Option
4) requires an extra switch, which has yet to be mentioned.
o
Variable Range Option 2: External Variable Range Only
This option allows only an external signal to be used to set the range of the
programming pots – the Variable Range Control pot does nothing if no external range
signal is applied. A connection is required from “tip” lug of the External Variable
Range input to the left lug of the Variable External Range Pot. For banana jackers, as
always, this just requires a connection from the one lug of the banana jack to the left
lug of the Variable External Range Pot.
J18
Ext. Range
Signal
Input
Ground
Lug
Back
of
Pot
Tip
Lug
R22
Variable Range
Control
Figure 4-14: Connecting External Range Input Jack to Variable Range Pot (Opt. 2)
o
Variable Range Option 3: Auto Switched Internal/External Variable Range
Those of you who do not use banana jacks – this is your turn to chortle. This option
is not available if banana jacks are used. It uses a “normalled” connection to actuate
the function. It requires either a 1/4” jack or a 3.5mm jack with a normally closed
(n.c.) switch lug. It is from this switch lug that the connection is made to the right lug
of the Variable Range Control pot. When a plug is not inserted into the External
Range Signal Input jack, voltage supplied by the Analogue Board is applied to the
Variable Range Control. When a plug is inserted into the External Range Signal
Input jack, the voltage carried by that plug is applied to the Variable Range Control
pot.
First of all, make absolutely sure you know which lug of your jack is the n.c. switch
lug. Then
leave it unconnected
for now. You still want to connect the tip lug to the
right lug of the Variable Range Control pot. The connection is essentially the same as
Option 2, this is just to stress that the switched lug should not be connected now.
37