Mackie CFX12.mkII Owner's Manual - Page 20

GENERAL PRECAUTIONS AND CONSIDERATIONS NEVER bypass the AC plug's ground pin. This is dangerous! AC Power Distribution The majority of AC outlets encountered in homes and clubs (in the U.S.) are served by a 240VAC center-tapped service entrance transformer. This provides two phases of AC power on either side of the center tap, at 120V each. If lighting is used in a show, it is preferable to power the lights from one leg of the service, and power the audio equipment from the other leg. This will help minimize noise from the lights coupling into the audio (particularly if SCRs, or light-dimmer switches, are used). In order to minimize ground loops, the safety grounds for all the outlets should be connected to a common ("star") grounding point, and the distance between the outlets and the common grounding point should be as short as possible. When setting up for a show, oftentimes you are plugging into an AC power distribution system you know nothing about. You may even be faced with 2-wire outlets that are missing the third safety ground pin. It's a good idea to have a three-wire AC outlet tester in your toolbox so you can check the outlets yourself to make sure they are wired correctly. These testers will tell you if the polarity of the hot and neutral wires is reversed and if the safety ground is disconnected. Don't use an outlet if it is wired improperly! This is to protect yourself as well as your equipment. If you find that you must plug into a twowire outlet, you will need to use a two-wire to three-wire adapter (cheater plug). These come with a metal tab that you put underneath the center screw that holds the AC outlet faceplate in place. This center screw must be grounded. You can check it by connecting the adapter to the outlet and then plugging in your handydandy AC outlet tester. APPENDIX A: Service Info If you think your Mackie product has a problem, please check out the following troubleshooting tips and do your best to confirm the problem. Visit the Support section of our website (www.mackie.com/support) where you will find lots of useful information such as FAQs and other documentation. You may find the answer to the problem without having to send your Mackie product away. Troubleshooting Bad Channel • Is the ASSIGN switch set correctly? • Is the channel Fader turned up? • On mono channels, try unplugging any INSERT devices. • Try the same source signal in another chan- nel, set up exactly like the suspect channel. Bad Output • Are the SUB ASSIGN switches set correctly? 20 • Are the MAIN MIX Fader and SUB Faders turned up? • If it's one of the MAIN OUTs , try unplugging all the others. For example, if it's a TRS MAIN OUT, unplug the associated XLR outputs. If the problem goes away, it's not the mixer. • If it's a stereo pair, try switching them around. For example, if a left output is presumed dead, switch the left and right cords, at the mixer end. If the left speaker is still dead, it's not the mixer. Noise • Turn the channel Faders , EFX 1 RETURN and EFX 2 SEND down, one by one. If the sound disappears, it's either that channel or whatever is plugged into it, so unplug whatever that is. If the noise disappears, it's from your whatever. Power • Our favorite question: Is the POWER switch on?