Control Faults
Control faults will typically result in either the corruption of display information, or the failure of encoders and switches. The
majority of the console’s display and control functions are performed by the 629505X1 CPU, which is located behind the centre
section meter panel. The CPU uses several serial data busses to carry control data, such as fader position data and switch presses,
to the CPU as well as display data, such as LED illumination commands, to the displays and motor drive information to the faders.
Referring to the Matrix Control Block Schematic you will see that there are four Digital Data bus connections to the CPU:
The first, labeled ‘Router’, is daisy chained through the right hand 626516X1 assembly into the left hand assembly and controls
the routing matrix.
The second, labeled ‘Tile-control’, daisy chains through the 629506X1 into the 626507X1, back into the 629506X1 and the
through the two 629502XA solo and cut panels. This data chain carries switch presses and rotary encoder data to the CPU and
corresponding LED and display data back from the CPU. Additionally this data chain also carries channel strip TR object data which
is converted from analogue to digital position data on the 629502XA assemblies.
The third connection, labeled ‘Channels’, connects the 629515X1 and 629511X1 assemblies to the CPU using a ‘Y’ split cable and
then daisy chains through the 629511X1 to the two 629510X1 assemblies. This third connection also carries switch press data
from the analogue modules and LED data from the CPU. This connection also carries a separate MDAC (Multiplying Digital to
Analogue Converter) control bus which writes gain data to the channel and centre section MDAC elements.
Finally the forth connection, labeled ‘meters’, daisy chains through the three meter assemblies driving the LED bar graph displays.
All of these data chains are ‘point to point’ connections and as such if any one of the assemblies fails or is removed then the flow
of data will be interrupted and assemblies after that point in the chain will fail to function.
The following example highlights a data bus fault and explains how the fault might be located.
After powering on the console you notice that the data displays for channels 1 to 8 are blank and the corresponding solo and cut
switches work but do not illuminate.
Once again refer to the Matrix Control Block Schematic. From the diagram you can see that data bus for the left 629502XA
assembly is connected to socket labeled ‘out’ on the right 629502XA assembly and the power is supplied from the left hand
629516X1 routing assembly. From the fault description we know that the data from the switches is reaching the CPU so the power
to the assembly must be good so we can rule this out.
We know that the display data is reaching the right hand 629502XA assembly as the displays and LEDs are functioning correctly.
From this we can conclude that the problem must be with either the output of the right assembly or the input of the left 629502XA
assembly. This leaves three potential causes. The first is that the data ribbon connection between the two panels is not seated
correctly. The second is that the input stage to left hand 629502Xa assembly is faulty. The third is that the right hand panel has
a faulty output stage.
To eliminate the first possibility, power down the console and gain access to the PCB side of the 629502XA assemblies (refer to
Replacing Modules information at the end of this section). Remove and then reinsert the 34 way ribbon connector between the
two 629502XA assemblies to ensure that a sound connection is made. Re-assemble the console and check the condition of the
fault. For the sake of the example we will assume that this did not resolve the problem.
The next possibility to eliminate is that one of the 629502XA Panels is faulty. Power down the console and swap the two
assemblies. Re-power the console. If the panel originally in the left hand position was faulty, then neither panel will now function.
In this cause you should revert to the original configuration and replace the faulty panel. If, however, the problem was due to the
failure of right hand panel’s output stage, then you should find that both assemblies are now functioning correctly. As the left hand
panel is not required to buffer data onto another panel, this fault will not effect the operation of the console and can be left in
this position allowing you to continue working unhindered.
Appendix G - Service
133
Matrix
2
Owner’s Manual
