Maintenance 5-1
130446-1 Rev. A
MA-5002VZ Service Manual
©2000 Crown International, Inc.
5.1 Cautions and Warnings
DANGER: The outputs of this amplifier can produce
LETHAL energy levels! Be very careful when making
connections. Do not attempt to change output wiring
until the amplifier has been off at least 10 seconds.
WARNING: This unit is capable of producing high sound
pressure levels. Continued exposure to high sound pres-
sure levels can cause permanent hearing impairment
or loss. User caution is advised and ear protection is
recommended when using at high levels.
WARNING: Do not expose this unit to rain or moisture.
WARNING: Only properly trained and qualified techni-
cians should attempt to service this unit. There are no
user serviceable parts inside.
WARNING: When performing service checks with the
power off, discharge the main power supply filter ca-
pacitors fully before taking any measurements or touch-
ing any electrical components. A 300-ohm 10-W resis-
tor is recommended for this. Hold the resistor with pli-
ers, as the resistor may become extremely hot.
WARNING: Under load, with a sine wave signal at full
power into both channels, the amplifier may draw in
excess of 30 amperes from the AC service mains.
WARNING: Do not change the position of the Mode
Switch when the amplifier is turned on. If the position of
this switch is changed while the amplifier is powered,
transients may damage your speakers.
WARNING: Heatsinks are not at ground potential. Si-
multaneously touching either heatsink and ground, or
both heatsinks will cause electrical shock.
CAUTION: Eye protection should be worn at all times
when protective covers are removed and the amplifier
is plugged in.
CAUTION: Disconnect the power cord before install-
ing or removing any cover or panel.
5.2 General Information
In most cases you will be using the test procedures in
Section 5.4 after conducting your repairs. Before ini-
tially powering up the amplifier you should review Sec-
tion 5.1 and take appropriate steps for personal and
equipment safety. Section 5.3 will help to determine
whether the amplifier should be safe to turn on.This
section also includes some additional checks that
should be made prior to starting the actual check-out.
Italicized print in the test procedures (Section 5.4) in-
cludes basic troubleshooting hints to augment proce-
dures in Section 5.3. These hints do not cover every
possibility, but should be helpful for a variety of symp-
toms. After troubleshooting and repair (or as a part of),
the final step is to thoroughly test the amplifier to be
certain that it meets the factory specifications. Test pro-
cedures in Section 5.4 will help you do this as well as
aid you in locating the cause of problem(s).
5.3 Troubleshooting
5.3.1 Pre-AC-Checks
A number of checks can be made prior to powering up
the unit. These should be done in order to prevent an
unwanted disaster when turning the unit on. Once these
checks are made power may be applied for further
checks. Note: It will be necessary to remove top, rear,
and bottom panels for complete access to all modules.
Step 1: Acquire all information possible from the
person(s) having the problem to determine the nature
of the complaint. Ask questions like “Why was the am-
plifier brought in for repair?” “Does it do this right at turn
on, does it take a while, or does it only happen some-
times?” If you observe nothing wrong, inquire tactfully
how the unit was being used when the malfunction oc-
curred to determine if it may have been misused, if the
user misunderstood what happened, or if another sys-
tem component may be at fault.
Step 2: Always do a complete visual inspection. A prob-
lem may be obvious just by looking. Things to look for
include burned components, wires not connected, fan
obstructions, loose hardware or connections, and sol-
dering. Dirty air filters or plugged heatsinks greatly re-
duce amplifier efficiency and result in pre-mature ODEP
limiting. The fan blades should spin freely. Burns and
other physical damage should be repaired and com-
ponents in the affected circuit areas should be checked
carefully before continuing.
Whether a problem is identified by visual inspection or
not, several checks should be performed prior to turn-
ing the amplifier on. These should be performed if cata-
strophic failure has been reported, no signal output with
constant IOC is reported, or the condition of the ampli-
fier is otherwise unknown but failure is suspected.
Channel 1 uses 100/300 series numbering and chan-
nel 2 uses 200/400 series numbering on the main mod-
ule. 500 series numbering is used on the output and
emitter modules, regardless of the channel. 700 and
800 series numbers are used on control, current sense,
and terminator modules.
The third item on the “to do” list involves a number of
electrical checks. Due to the protection features of the
MA-5002VZ, it should be safe to turn-on under all cir-
cumstances, but these preliminary checks may allow a
5 Maintenance
To Next Page
Loading...
