Service manual

6
Introduction
The Midas XL3 series of consoles has been designed not only to provide the highest possible
quality sound processing facilities, but also the greatest possible degree of reliability. However,
no unit of such complexity can be expected never to need service, and to help anyone undertaking
such work circuit descriptions will be found below. The less experienced technician or operator
may find the following notes useful in emergency fault finding when more experienced help may
not be available.
The priority in console fault finding is to adopt a logical approach, as this is the quickest way
to identify the precise source of a problem. For instance, if an input module appears to have
failed, it will be helpful to establish with greater accuracy where the failure is. Does the signal
return if the equaliser is switched out? [Failure in equaliser section]. Is it present at PFL? Does
it route to all mixes but not to the masters? [Fault in pan buffers or pan pot]. Are mix sends
affected both pre- and post-fader? In this way a particular circuit block can be identified as faulty,
and a careful inspection will often reveal a disconnected wire, a damaged component, or a suspect
IC can be changed. Furthermore, if help is sought over the telephone, it will be helpful to have
the greatest possible amount of detail for the technician to work with.
When performing tests on the console, it is tempting to take modules in or out of the console
frame without switching off the power supply. THIS MUST NEVER BE DONE, AS IT NOT
ONLY DESTROYS SOME COMPONENTS AT ONCE, BUT LEADS TO THE EARLY
FAILURE OF MANY THAT APPEAR TO HAVE SURVIVED. The power supply is designed
to bring the console to full power gradually, which protects sensitive components from damage
caused by voltage spikes created by sudden powering up.
Two extender card sets can be supplied which allow active tests to be performed on modules
while they are out of the frame but powered up. Care must be taken that the bottom of the p.c.b.
is not allowed to rest on anything metal which could short-circuit the tracks.