Linear Acoustic UPMAX, User Manual

Linear Acoustic UPMAX User Guide

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Chapter 5: Troubleshooting

The Linear Acoustic UPMAX is a very stable and reliable unit, and most problems can be 
traced back to mis-wiring causing incorrect signals to be applied to the unit, or more than 
likely mis-configuration. In an effort to speed troubleshooting, some common problems 
and solutions are described below.

5.1

Problems and Possible Causes

One of the best troubleshooting features of the UPMAX is the hard-bypass of the audio 
signals. This is useful because it allows instant removal of the unit from the signal path. 
Hard-bypass can be accomplished two ways, the simplest being to remove AC power from 
the unit by turning the power switch off. A less dramatic way to accomplish the same result 
is to access the System Options menu and enable Master Bypass. If you are unsure of what 
is happening in a particular system, simplifying the signal path is a good start and will help 
isolate problems quickly.

5.1.1

Unit won’t power on

Check to make sure that the unit is connected to a live outlet (it happens...). If proper AC 
voltage is being applied to the unit, remove power and check the fuse (the IEC inlet mod-
ule has a fuse compartment that can be carefully opened with a small screwdriver). If the 
fuse is blown there is a spare in the holder. Install the replacement fuse, re-insert the fuse 
carrier, and re-apply power.

NOTE: Replace fuses only with the same size and rating: 5mmx20mm T1AL (250V)

5.1.2

Output Audio Clicks and Pops

This could indicate that the AES Reference is missing or at the wrong sample rate (the unit 
expects to be locked to 48kHz). The unit is designed to default to an internal 48kHz ref-
erence in case the external reference is removed. This allows audio to continue, but due to 
the sample rate converters present on each input pair, the outputs will be asynchronous 
with the inputs. The solution is to make sure that the reference is connected.

It could also mean that audio applied to the unit is not properly referenced, or that the 
equipment that the unit is feeding is not properly referenced. Using the master bypass 
function of the unit is a helpful way to troubleshoot this issue.