AWS 924-948 - Solid State Logic

G: TroubleshootingUnlike the Multidrop Bus which allows modules to be added and removed from the bus without effecting its integrity, theLive Bus passes through one module to the next. Therefore the removal of a Live Bus module may potentially disruptother modules, depending on its position in the data chain.When fault finding Live Bus problems the same principles can be applied, as the following example shows. During a mixyou suddenly notice that the channel meters in Bay 1 are all showing random patterns of illumination.As always the first step is to refer to the AWS Control Block Schematic. From the diagram you can see that Live Bus datafrom the CPU passes through Bay 2 and 3’s Channel Meter Panels before reaching the Meter Panel in Bay 1. As the channelmeters in Bay 2 are functioning correctly, you can rule out the CPU and Bay 3’s Meter Panel as potential causes of theproblem. This leaves three potential causes. The first is that the data ribbon connection between the two panels is notseated correctly. The second is that the input stage to Bay 1’s Meter Panel is faulty. The third is that Bay 2’s Meter Panelhas a faulty output stage.To eliminate the first possibility, power down the console and re-seat the 16-pin IDC connector between the two panels.Re-power the console and check the condition of the fault. As in previous examples, we will assume that this did notresolve the problem. The next possibility to eliminate is that one of the Meter Panels is faulty. Power down the consoleand swap Meter Panels between Bays 1 and 2. Re-power the console. If the panel originally in Bay 1 was faulty, then neitherBay 1 or 2’s metering will now function. In this cause you should revert to the original configuration and replace the faultypanel. If, however, the problem was due to the failure of Bay 2’s Meter Panel output stage, then you should find that allyour meters are now functioning correctly. As Bay 1 is not required to buffer data onto another panel, this fault will noteffect the operation of the console and can be left in this position allowing you continue working unhindered.Replacing ModulesHaving identified the source of the problem, you are now in a position to replace the faulty part. If you purchased an AWSspares kit, then locate the relevant assembly and follow the replacement instructions below. If, however, you do not havea replacement card to hand, you should contact your local SSL distributor who will be able to supply you with areplacement.Removal of modules while power is applied to the console will almost certainly result in component failureThe channel and centre section modules can easily be removed from the console for replacement, but first you mustdisconnect the console from its AC power source. Before turning off the power, make sure that you switch off, oroverpatch, all monitor sends. If you power down the console with any of these connected, the DC thump generated couldpotentially damage your monitors.AWS 924-948 Operator’s Manual Appendices Page A-15