TM

Quantum -combo Manual

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!

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.

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Hughes & Kettner QC 412, QC 421, QC 415 manual Service and Maintenance, Troubleshooting