Lexicon MC-1, Service Manual

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MC-1 Service Manual
5-12
User Interface Problems:
Remote Control
A remote control may not function properly for a variety of reasons. The top (end) of the remote must be
pointed directly toward the MC-1 with out any obstructions between the remote control and the unit for
proper transmission of the data sent at infrared frequencies. Excessive ambient light conditions can also
interfere with data transmission. In addition, a remote control held within a few inches of the MC-1 may not
function properly, as the IR receiver can be overloaded at close distance.
If the remote control is not functioning after all of those conditions have been corrected, replace the
batteries. Remember to use only alkaline-type batteries. If the remote still does not function, try another
MC-1 remote control if available. If both remotes fail to work, the problem may lie within the MC-1.
Front Panel Display and IR Receiver
Verify that the cable connections from the Main board (J30, J31) to the front panel VFD and IR boards are
secure.
Excessive vibration can eventually break the strands of cables making them intermittent or possibly open.
Connections can become oxidized, corroded or otherwise contaminated causing them to become
intermittent, open, or resistive. For all of these reasons, caution should be used in troubleshooting. Before
removing any cables, inspect them carefully for proper seating and continuity at all points.
Verify that the +5VD supply is operational and within specification. Check the distribution of the supply to
ensure that power is reaching the appropriate front panel boards.
Switch, Encoder and LED problems
If only one front panel control is failing, then the problem is properly a bad switch, encoder, or LED. For
problems specific to the front panel power switch or volume encoder, verify the cable connections from the
Main board (J29, J27, and J25) to the front panel power switch and the Encoder board. If more than one
control is failing, the problem may be with the main processor.
Audio Problems
When troubleshooting any kind of equipment, intermittent problems are among the most difficult to trace.
The first step is to collect as much information as possible of the problem. The following list presents some
basic questions that should be answered before attempting repairs.
Does the problem occur …
• on only one output?
• at only certain signal frequencies?
•
at certain signal levels ?
•
in a particular program?
• At a specific sample frequency? ( 44.1 or 48 kHz?)
• with input only ?
•
with output only?
•
Is the problem temperature sensitive hot / cold ?
• Is the problem shock sensitive? Does tapping on it make it appear ?
In general, it is best to run all of the audio proof-of-performance tests to verify the overall performance and
to further isolate the problem in the MC-1. This can be vital when troubleshooting subtle problems. Although
system failures may cause a variety of tests to fail, troubleshooting may be much easier for some specific
test failures than others.