Kurzweil K2000 Service Manual page 53

MAINTAIN. PUB
11/04192
SECTION 4
4.6.3
4.6.4
4.7
4.7.1
4.7.2
4.7.3
4.7.4
For studio applications, where the utmost signal purity is
required, using audio unbalanced-to-balanced line transformers
will give you the best results. Each of the K2000's audio
outputs can easily drive a 600 ohm transformer.
Finally, magnetic fields can be a source of interference. The
area surrounding the K2000's Alpha Wheel and alphanumeric pad is
sensitive to fields from large transformers in power amps; keep
them at least a foot away from the K2000's front panel. Smaller
gear like drum machines and hardware sequencer can also cause
interference.
POWER PROBLEMS AND SOLUTIONS
The K2000 is quite tolerant of voltage fluctuations, noise, and
transients in the AC power it receives. The input line filter
and grounded power cable will protect against even large amounts
of noise from motors and the like while the built-in filter
coupled with the fuse will protect against all but the largest
transients. If your installation is actually suffering from
line noise or transients, most likely your other equipment will
be suffering more than the K2000.
Very low line voltage or severe voltage dips are a problem for
any computer-based instrument. When the K2000 is set for 120
volt input (the normal North American setting), it should
function down to 90 volts. If the line voltage drops below 90
volts, a special circuit halts all activity to protect against
software crashes or damage. When the line voltage returns to
and stays at an acceptable level for at least one second, the
computer will automatically restart. The net effect is just as
if you had performed a soft reset. Continuous low line voltage
or transient dips will never produce symptoms other than
unexpected soft resets as just described. Any other problems
such as distortion, disk errors, or lost data are cause by
something other than line voltage fluctuations.
Soft resets from line voltage dips are most common. These are
easily identified because the reset occurs coincident with the
building lights dimming, stage lights or power amps being
switched on, or air-conditioning equipment starting up. The
solution in all cases is to get a more direct connection between
your K2000 (and any other computer-based equipment) and the
building's power. Floodlights, large power amplifiers, and
motor-operated devices should use a separate extension cord;
preferably they should be plugged into a separate outlet.
Chronic low line voltage is best confirmed by measurement.
Readings below 100-105 volts mean that even small dips could
cause resets, while readings below 95 volts (accounting for
meter inaccuracies) are a definite problem. Again, the best
solution is to separate your heavy lighting and amplifier loads
from your K2000 and other synths on separate extension cords or
separate circuits when possible. If the actual building voltage
is that low, use of an external step-up transformer or voltage
regulator is recommended. we DO NOT recommend changing the line
voltage to 100 volts (220 volts in Europe) because overheating
or blown fuses may occur if you leave the K2000 at the lower
setting and use it later at a normal voltage level.
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