Hughes & Kettner Quantaum Combos QC 412 - Manual (Page 10)

7. Troubleshooting
The amp won't power up when you switch it on.
• It's not getting AC power. Check the mains cable to see if
it is connected properly!
• The mains fuse is defective. Replace the fuse with another fuse
with identical ratings. Turn to your local Quantum dealer.
The amp is cabled up and connected properly, but no sound is
audible.
• The GAIN and/or MASTER controls are turned all the way
down. Dial in a higher setting
• A connected effects processor’s cords are plugged in incorrectly
or the device is off. Check out the FX signal chain.
• Headphones are plugged into the headphones jack, which
automatically switches the internal speaker off.
Unplug the headphones.
The LINE OUT jack causes humming noises when in use.
• An electrical or magnetic field is generating interference.
Use a better quality cord or try to reposition cables to minimize
interference. If this doesn't solve the problem, use the DI OUT,
TUNER output or a DI-Box.
• The connected devices’ grounds have created a ground loop.
Never sever the ground of connected devices! Try plugging all
devices into the same power distributor. If this doesn't eliminate
the noise, ensure the connection is galvanically separated by rou-
ting the signal through a DI-box.
You have connected a mixing console to the LINE OUT jack and
the signal sounds totally distorted over the PA.
• The mixing console's input is not set to line level. Adjust the level
accordingly at the mixing console. If for some reason this is not
possible, patch the signal to an unbalanced line input at the
mixing console or use a connecting cable equipped with an
integrated balanced voltage divider (available from quality
music stores or PA service companies).
Feedback arises when the DI OUT is in use.
• If the PA’s sound pressure is extreme enough, it can excite the
amp’s speaker and cause feedback when using the DI OUT.
The speaker’s response influences the power amp, which routes
this interference signal to the DI OUT. Try repositioning the amp
or using the LINE OUT instead.
The amp's output level is too low.
• A device connected to the effects loop is reducing the signal level.
Adjust the signal level via the device's input/output control.
6. Service and Maintenance
Quantum amps do not require service of any type. There are how-
ever a few basic rules that – if you follow them - are sure to extend
the service life of your amp enormously:
• Make sure all peripheral devices, cords and cables are in a state
of good repair!
• Ensure plenty of air can circulate around your amp's ventilation
ducts at all times.
• Definitely avoid exposure to mechanical shocks, extreme heat,
dust and moisture.
• Be picky about the kind of peripheral devices you connect to your
amp and always check out their specs before you plug them in.
Under no circumstances should you connect devices with high
output signal levels (e.g. power amps) to your amp's input.
• Be sure the AC power source delivers the current that your amp
is designed to handle before you plug it in. When in doubt about
the local rating, ask the venue's sound technician or a stagehand.
• Refrain from DIY repairs! Have an experienced technician replace
internal fuses.
• Use a soft dry cloth to clean the enclosure’s outer surfaces
and exterior metal parts. Never use alcohol or other solvents
to do this!
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Quantum TM -combo Manual
Quantum_Combos_Manual_1.3 29.10.2003 14:59 Uhr Seite 10