Usl JSD-80 Manual page 36

PROBLEM
SOUND IS
DISTORTED
HUM IN ALL
CHANNELS
BUZZING SOUND
IN ALL CHANNELS,
MAINLY
THE SURROUNDS
STEREO MODE-
SOUND FROM LEFT
OR RIGHT CHANNEL
ONLY
USL, Inc. JSD-80 Instruction Manual
CHECK
Power amplifi er or
speaker
Press several format
buttons
Try NON/SYNC
MUSIC
STEREO mode
Exciter lamp
Stray light pickup at
the solar cell on the
projector
PREAMP Module
Wiring between the
processor and power
amplifi ers
INPUT module
LED indicators on
INPUT module
Page 36
SOLUTION
Try to determine if distortion is in one or
all channels. If distortion is one channel,
exchange power amplifi ers or speaker lines
to locate problem.
Try to determine if one or all formats are
distorted.
If MUSIC is not distorted, the problem is
in the input module or the SOLAR CELL
alignment.
If there is distortion only in this mode then
there could be a problem in the input module.
Make sure correct lamp is used. There are
vertical and horizontal versions of many
exciter lamps. Soundhead misalignment can
cause distortion.
Eliminate source of stray light.
Eliminate cause of hum ground loops, bad
exciter lamp supply, JSD unit located too
near hum fi eld from power amplifi er or
another piece of equipment.
The Input may have some high frequency
oscillation. Check the Solar Cell wiring. Make
certain that the lines are not routed too close
to the Power Amplifi er or Loudspeaker wiring.
It may be necessary to re-route the cell lines.
If in doubt remove wires from the backboard
and short the input. If this does not solve the
problem, replace the Input module.
If only the left or right LED indicator is lit with
program material, check the projector wiring
and input module.
3rd Edition. February, 2006