Radio Systems Millenium-A Analog Console, Инструкция по установке и эксплуатации

Страница: 43 / 88

Radio Systems Millenium-A Console Page 43
Maintenance and Troubleshooting
6.1 Overview
There is no required maintenance for Millenium consoles. Front panel level controls and switches will not become noisy
since they control only DC for the VCAs and CMOS analog switches. A very dirty fader control will skip levels erratically.
Normal cleaning agents may be used to clean the controls.
Painted surfaces should be cleaned with a warm damp cloth with mild detergent. Avoid any solvents that might attack
plastic switches or meter and clock lenses.
Vacuuming or blowing dirt off of circuit boards occasionally is also recommended. Do take care to avoid dropping wire
clippings on the large horizontally mounted circuit boards during console installation and maintenance.
Millenium consoles are designed for ease of repair should it become necessary. Connectors are used to make all circuit
board connections. Replacement mechanical components (faders, pots) come prewired with connectors to allow quick
replacement without soldering.
6.2 Power Supply
Read the Power Supply Theory of Operation prior to troubleshooting. The power supply provides all voltages for the
console. Front panel LEDs monitor the DC outputs from the supplies. A second 15v LED monitors an optional power
supply module which can be provided for extra current needs. The power supply modules are internally fused. The +
and -7.5v outputs are regulated and derived from the + and - 15v supply.
Each regulated output has independent short circuit protection. Before suspecting the power supply of defect, unplug
the power supply from the console and check the LEDs.
If the +15v and +7.5v LEDs are not illuminated the +15v supply should be checked for fault (either a defective supply or
s15v output) since the +7.5v has been derived from the +15v output.
If a fault is detected in one of the internal power supply modules, contact the factory for replacement. Do not attempt
repair.
6.3 Six Channel Audio Board
Read the Theory of Operation prior to troubleshooting. The Six Channel Audio Board contains six identical stereo cir-
cuits. Each circuit is controlled by an individual Input Control Board. If both the left and right channels are not operating
properly, or if the input cannot be placed into the cue mode, swap the Six Channel Control Board with one from a known
good input before suspecting the Six Channel Audio Board of defect. This can be accomplished by interchanging ribbon
cables at header J9 on the Six Channel Audio Board. If the problem is resolved, the Six Channel Control Board or as-
sociated components, such as switches, fader, or interconnecting cable is at fault.
If the problem is not resolved, signal tracing and voltage measurement techniques maybe used. If the problem is oc-
curring in both left and right channels, the problem will most likely be with the control voltages for the CMOS analog
switches or for the VCAs.
Check for signal at the insert point return, at the output of U3C and U4D, and at the output of U8A and U8B.
If there is no signal or the wrong signal (A instead of B input), at the insert point and this is occurring in both left and
right channels, suspect a problem with the control voltages at Ul and U2. A bad ribbon cable connection at header J9, a
defective IC at Ul and/or U2, or defective D1, D2, R25, or R32 can cause this problem. If the problem is not occurring in
both channels, Ul and/or U3 (left channel), or U2 and/or U4 (right channel) should be suspect. Substitution with new ICs
will produce the fastest results.
If there is no signal at the output of U3C or U4B with signal present at the insert point, then replace U3 or U4.
If signal is present at the output of U3C and U4B but is not present or is at the wrong level at the output of both U8A and
U8B, the VCA control voltage should be suspect; replace U7. If desired the control voltage can be carefully measured
at pin 1 of U7. With the fader at maximum the voltage will be approximately negative .07v. With the fader at minimum
the voltage will be approxi6v. If the problem is not occurring in both channels, suspect U6 and U8 (left channel),
or U5 and U8 (left channel). U8 should be substituted first. If the VCA is replaced, a distortion null adjustment must be
made.
If signal is present at the output of U8A and U8B but there is no signal on both the left and right of the mix buses or if the
signal is routed to the wrong mix buses, the control voltages to U10 and U9 should be suspected. A bad ribbon cable