SBIG SG-4 User manual

Application Note
SG-4: Installing Jumpers for
+12V and Ground on the Guide Port
May 25, 2010
Introduction
The SG-4 provides mechanically isolated relays to connect the +X, +Y, -X, and –Y signals to the
Common input on the Guide Port. This is sufficient for most applications and all consumer telescope
guide ports SBIG is familiar with.
As shipped from the factory, the Guide Port pin-out is as shown here:
When one of the guide signals (+X, +Y, -X, -Y) activates, the SG-4 connects the signal to the Common
pin on the Guide Port. The Common pin and the NC pin have no other connection to the internal
electronics of the SG-4.
However, some systems, such as the SBIG Relay Box, may require power (+12V) and/or Ground on the
Guide Port. The Common pin can be connected to the SG-4 Ground and the NC pin can be connected to
the SG-4 +12V power signal if necessary.
This application note describes how to install jumpers in the SG-4 to connect +12V and Ground to the
Guide Port.
NOTE: Be aware that this procedure is not recommended for most users and should only be done if you
know for certain that you need +12V and/or Ground on the Guide Port. If you are not sure, DO NOT
follow this procedure.
_________
SBIG
ASTRONOMICAL
INSTRUMENTS
Santa Barbara Instrument Group
147-A Castilian Drive
Santa Barbara, CA 93117
Phone [phone] FAX [phone]
e-mail: [email protected] web site: www.sbig.com

Removing the SG-4 Rear Panel
The Rear Panel of the SG-4 must be removed to access the internal electronics. See Figure 1 for a photo
of the SG-4 Rear Panel.
Figure 1
In order to remove the Rear Panel of the SG-4, a number of things must be removed from the camera.
First, pull off the button cover from the Guide On/Off button (1).
Next, using needle-nose pliers, or similar, remove the nut from the Power In connector (2), and the I
2
C
and RS-232 port nuts (3).
Finally, remove the four Phillips-head screws from the corners (4).

This will expose the circuit boards of the SG-4 as shown in Figure 2.
Figure 2
Behind the Guide Port on the right is a connector that accepts two jumpers to allow the connection of
+12V and Ground to the Guide Port. A better view of the connector is shown in Figure 3.
Figure 3

Installing the Jumpers
Two small 0.1” Jumpers must be used on this connector to make the necessary connections. These
jumpers can be obtained at most any electronics store, or can be purchased from SBIG for a small
charge.
To connect the Common pin to the SG-4 Ground, one jumper should be installed on the rear two pins of
the connector as shown in Figure 4.
Figure 4
The connect the NC pin to the SG-4 +12V, one jumper should be installed on the front two pins of the
connector as shown in Figure 5.
Figure 5

Jumpers can be installed in both positions to connect Ground to the Common pin and +12V to the NC
pin. This configuration is shown in Figure 6.
Figure 6
Once the jumpers are installed, replace the SG-4 Rear Panel and reinstall the screws, nuts, and button
cover in the opposite order than they were removed.