Mackie HM54 Owner's Manual - Page 10

HM-54 Appendix A: Service Information Warranty Service Details concerning Warranty Service are spelled out in the Warranty section on page 15. If you think your HM-54 has a problem, please do everything you can to confirm it before calling for service. Doing so might save you from the deprivation of your headphone amp and the associated suffering. These may sound obvious to you, but here are some things you can check. Read on. Troubleshooting No Power • Our favorite question: Is it plugged in? • Make sure the power cord is securely seated in the IEC socket [6] and plugged all the way into the AC outlet. • Make sure the AC outlet is live (check with a tester or lamp). • Is the POWER [5] switch on? Make sure the POWER switch on the front panel is in the ON position (up) and the power LED is lit. • Are all the lights out in your building? If so, contact your local power company to get power restored. • If the power LED is not illuminated on the front panel, and you are certain that the AC outlet is live, it will be necessary to have your HM-54 serviced. There are no user serviceable parts inside. Refer to "Repair" at the end of this section to find out how to proceed. Bad Output • If you are listening to a PHONES OUTPUT [8] on the rear panel, make sure that nothing is plugged into the corresponding PHONES out on the front panel. • If only one side of the stereo headphones is working, make sure you have a signal at both inputs. There must be a signal present at both inputs [7][9][10] to get a signal in both sides of the headphone output. Bad Sound • Is the input connector plugged completely into the jack? • Is it loud and distorted? Make sure the input LEVEL [4] control for the channel is set correctly. Reduce the signal level on the input source if possible. • If possible, listen to the signal with headphones plugged into the input source device. If it sounds bad there, it's not the HM-54 causing the problem. Noise/Hum • If connecting an unbalanced source to the balanced inputs on the HM-54 using a TS-to-TS 1/4" cable, it could cause a ground loop. Refer to "Unbalancing a Line" for more info on connecting an unbalanced source to a balanced input. • Sometimes it helps to plug all the audio equipment into the same AC circuit so they share a common ground. Bad Channel • Is the input LEVEL control [4] for the channel turned up? • Is the signal source turned up? Make sure the signal level from the selected input source is high enough to drive the line-level inputs on the HM-54. • Try the same source signal in another channel, set up exactly like the suspect channel. 10 HM-54