Troubleshooting - Yamaha EM-300B Operating Manual

Troubleshooting
The following chart may be helpful if you encounter difficulty with your EM-Mixer.
DIFFICULTY
NO POWER
(VU Meters have no light or level)
NO SIGNAL OUTPUT
(VU Meters moving)
(VU Meters light, but do not move)
VERY LOW SIGNAL LEVEL
(Channel and Master Volume
controls turned up)
FUSE BLOWN
POSSIBLE CAUSES
1.
2.
GO м A сә м ‫د‬‎ N>
со № =
Mixer is not plugged into a "live" AC outlet.
Fuse is blown. Replace with same size and type.
If fuse blows again, see "Fuse Blown" below.
. Speakers are incorrectly patched to outputs.
. Speaker cables or connectors are open/shorted.
Input Channel Volume controls are at 0.
. Input Level switch is set improperly for channel source.
. Inputs are incorrectly connected or connected to wrong
impedance jack.
. Master faders are at O.
. Microphone or line input level is too low to drive Mixer
(Needs matching transformer or preamplifier).
. Input Level switch is not set properly.
. Excessive EQ cut on Input Channel or Graphic Equalizers.
. Mixer output is patched back into a Mixer input.
. Hi-level amplified signal is fed to Mixer input.
. Short in Speaker, Monitor, Line Out, G-EO out or other cables.
. Overheating due to covered top-panel vents,
Caution: Replace fuse with one of similar size and type. If second fuse blows refer to authorized Yamaha
service center.
Never use a fuse of higher rating than that specified. Doing so will only cause damage to your Mixer.
SOUND IS DISTORTED
FEEDBACK
LOUD BUZZING
1.
2.
3. Input signal is too strong. (Use a "direct box" to lower the level).
Channel or Master Volume is too high (VU meter pinning).
Input Level switch is too low.
1. Microphones are placed in front of speakers.
2.
3. Graphic Equalizers are set for too much boost.
Channel EQ is set for too much boost.
. Shorted cables or circuits. Turn off AC Power at once. Double
check input and output connections, and replace damaged or |
suspect cables.
. Ground loop or input source problem. Unplug all inputs to
Mixer and check each individually until buzzing starts.
Buzz does not necessarily indicate a problem in the equipment,
but may require the use of a common AC power line, addition
or elimination of ground connections, or use of shorter cables.
23