MACKIE HMX-56 - Manual (Page 10)

10
HMX-56
HMX
-56
Appendix A: Service Information
Warranty Service
Details concerning Warranty Service are spelled out in
the Warranty section on page 15.
If you think your HMX-56 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 [7] 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 [8] switch on? Make sure the
POWER switch on the rear panel is in the ON
position (up) and the POWER LED [6] is lit.
• Are all the lights out in your building? If so, contact
your local power company to get power restored.
• Is the fuse blown? If the POWER LED is not
illuminated on the front panel, and you are certain
that the AC outlet is live, it is possible the fuse has
blown.
To remove and replace the fuse:
1. Disconnect the linecord from the IEC socket.
2. Remove the fuse drawer by prying it open with a
small screwdriver. It will slide all the way out.
FUSE
3. Remove the fuse and replace it with an equivalent
type fuse: 250 mA slo-blo (T250mA/250V).
4. Replace the fuse drawer by pushing it all the way
back into the IEC socket.
5. Reconnect the linecord and turn the POWER switch
on.
If two fuses blow in a row, it will be necessary to have
your HMX-56 serviced. There are no user serviceable parts
inside. Refer to “Repair” at the end of this section to find
out how to proceed.
Bad Channel
• Is the SOURCE level control [1] for the channel
turned up?
• Is the signal source turned up? Make sure the signal
level from the input source is high enough to drive
the line-level inputs on the HMX-56.
• Try the same source signal in another channel, set
up exactly like the suspect channel.
Bad Output
• If only one side of the stereo headphones is
working, and you are listening to the MAIN INPUT,
make sure you have a signal at both inputs. There
must be a signal present at both inputs [9] 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 SOURCE
level [1] control and the PHONES level [3] control
for the channel are 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 HMX-56 causing the problem.
Noise/Hum
• If connecting an unbalanced source to the balanced
inputs on the HMX-56 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.