ATI Audio MX100 User Manual

Page 11

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POWER SUPPLY LEVELS

The recommended loaded DC input voltage range is 22 to 30VDC over the full range of
AC line voltage tolerances. The audio circuits continue to work with reduced headroom
below 22VDC but the LED VU meter will not indicate the top segments. Momentary
surges up to 36VDC will cause some increased internal heating, but above 36VDC, call
our parts department for some of those expensive ICs.

OPERATING POINTS

An internal reference voltage equal to 1/2 the supply voltage is generated by A9 in the
MX100 and A5B in the XP100. All audio stage inputs and outputs should show a DC
level equal to this voltage when measured with a high impedance meter. XLR audio
inputs and outputs are capacitor coupled and ground referenced. The expansion buss
input is at this DC reference level and must not be accidentally grounded by dangling
audio interconnects cables.

METERS CALIBRATION

To set, adjust the master gain control for the desired OVU output level in the range of +8
to -10dBm (+4dBm nominal) with an independent audio voltmeter. Adjust the internal
meter calibration trimpot, R70, for 0VU indication on the bargraph meter.

SWITCH MAINTENCE

The front panel MIC/LINE switches have good wiping contacts and should need little
attention. The switches are sealed and impossible to clean, in addition, most spray
solvents will wash out the internal lubricant and cause premature mechanical failure. A
good fix, if the switches get noisy, is to sit down at the unit, think about your girl friend
for a while (or Madonna or Mae West, depending on your age bracket) and push those
little red buttons about 500 times each. If that doesn't cure the problem, call us for more
sympathy and a high-priced replacement.

POTENTIOMETERS

Input and Master Gain controls are 10Kohm audio taper potentiometers. Replacements
are our P/N10034-2. The headphone pot is a 1M-ohm linear taper pot, our P/N10058-1.

This manual is related to the following products:

MX100C MX101 XP100