Maintenance and Troubleshooting
Power Problems and Solutions
9-4
Finally, magnetic fields can be a source of interference. The area surrounding the K2500’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 K2500’s front panel. Smaller gear like drum machines and
hardware sequencers can also cause interference.
Power Problems and Solutions
The K2500 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 your K2500.
Very low line voltage or severe voltage dips are a problem for any computer-based instrument.
When the K2500 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 caused 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 K2500 (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 K2500 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 selector to 100 volts (or 220 volts in Europe) because overheating or blown fuses
may occur if you leave the K2500 at the lower setting and use it later at a normal voltage level.
Troubleshooting
Naturally, we’ve done everything possible to ensure that your K2500 arrives free of defects.
And there’s a good chance that there’s nothing wrong, even if you’re not seeing the proper
display or hearing the sounds. Carefully check the following things:
Make sure that your power supply is at the right voltage, and is functioning properly.
Make sure the power cable is connected properly.
Adjust the display contrast if necessary (with the Contrast parameter in Master mode). If for
some reason you have trouble reading the display, even after adjusting the Contrast parameter,
you can also adjust the contrast by holding down the ENTER button and turning the Alpha
Wheel. If this improves the contrast, immediately return to the Contrast parameter and adjust it
slightly. This will cause the K2500 to remember the current display contrast level, and should
take care of any difficulties you may have been having. If this procedure doesn’t work, it’s time
to contact your dealer.
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