User Manual

4
Remove the four screws that secure the top panel and remove the panel.
The jumper is labeled " REMOVE JUMPER TO BLACK-OUT ON LOSS OF SIGNAL "
Remove the jumper.
Replace the top panel and secure with the four screws.
TEST MODE
The DMX512 to Analog Converter has a built in test mode which allows the outputs to
be brought up to full without any DMX512 input. To bring up a particular channel set
the starting address switch for 6XX where XX is the channel to be brought to full. For
example: To bring channel 1 to full, set the switch to 601. To bring channel 24 to full
set the switch to 624.
Test mode is useful for testing lamps and focusing. When in test mode, the signal LED
will flash to warn the user that the unit is not using the DMX512 input to set the levels.
TECHNICAL DETAILS
For those technical types out there, here is a brief description of how the DMX to
Analog Converter works.
DMX512 uses a "differential" digital signal. A differential signal is a pair of signals
which are inverse from one another. That is, when one is high, the other is low.
Differential signals are common in both analog processing (balanced microphone
cables) and digital processing (digital communications such as EIA-485). Differential
signals are used to reduce the effect of electrical noise on long cable runs. When a
differential signal is processed by the receiving circuit (microphone pre-amp or EIA-485
receiver for example) the noise can be eliminated but the signal remains.
Differential signals always travel in pairs, and the wires on which they travel are usually
twisted to insure any noise picked up is of equal magnitude on both wires. The noise
must be of equal magnitude on each wire so that the receiving circuit can effectively
subtract the noise and leave the signal. The pairs of signals are usually denoted by a
plus (+) sign on the normal, or "hot", or "true" line and by a minus (-) sign on the
inverted, or "return", or "complement" line. The differential signals on the combine unit
are Data+ and Data-.
DMX512 is a standard for lighting control published by the United States Institute For
Theater Technology. The DMX512 standard specifies that the electrical properties of
the signal comply with a standard published by the Electronic Industries Association,
EIA-485 (or RS-485). Many manufacturers make integrated circuits that meet the input
and output specification of EIA-485. The DMX512 to 0-10 Volt Analog Converter uses
the "75179" as its receiver. The "75179" was designed specifically to meet EIA-485.
The DMX512 signals from the console are applied to the input connector of the
Converter. These are received by "75179" and fed to an optical isolator. The signal is
passed through the isolator and on to an 80C31 micro-controller. The micro-controller
receives the digital signal, selects the DMX channels required based on the setting of
the starting address switch and sends these levels to a Digital to Analog converter chip