Kurzweil K2000 Service Manual page 72

SECTION 4
DIJ\GSO_'.DOC 12/22/92
lightly all the way down should display the same note name and MIDI number
a second time which indicates that the "lower contact" of the key has
closed. The two names/numbers should match. Most keyboard errors are
detected by the diagnostic which will display **ERROR ** in response. If
several keys seem to be bad, the problem is usually in the connecting
cables. Note: If none of the keys responds, yet the keyboard is known to
work, there may be interference from the pressure sensor. This will
usually go away if the unit is allowed to cool for awhile with the power
off. Units with serial numbers above 5000 should not be susceptible to
this.
J. If a keyboard key is pressed down firmly, the pressure sensing circuit will
begin to respond and the display will change to "PRESSURE = XXX." "XXX"
will vary between 4 and 255 according to how hard the key is pressed.
When pressure drops below 4, the display switches back to the note
name/number display. There is a pressure sensitivity adjustment on the
audio/power board (at location R201, near the large filter capacitor) that
may be changed to suit an individual customer.
NOTE: There are two additional internal signals called AUXI and AUX 2 that
are normally unused. If the fourth line ever shows "AUX 1" or "AUX 2,"
then there is likely a short circuit (usually to a cable running under the
board) or current leakage in the audio/power board.
The LCD based diagnostic may be exited and normal K2000 operation restored by
pressing the EXIT and ENTER buttons together. The K2000 should restart just
as if a soft reset had occurred.
4.16.2 Using the LED Scanner diagnostics
In cases where the K2000 appears to be "dead," the scanner microprocessor and
user interface controls may still be functional. If the eight panel LEDs
flash at all shortly after power-up, that's an indication that the scanner
processor is running which in turns means that the power supply is probably
functional.
To enter the LED Scanner diagnostics, press and hold the 7, 8, and 9 buttons
while the power is off then turn the power on while continuing to hold them
down. The panel LEDs will flash in inverse sequence to indicate entry into
the LED diagnostic. After the light show, the software version number ($14)
will be shown briefly in hexadecimal, followed by the battery voltage in volts
(left hex digit) and tenths (right digit) . The battery voltage should remain
on the display but early serial number units may display it only briefly.
The LED-based diagnostic uses the 8 mode LEDs for a two-digit hexadecimal
readout. The LEDs are sequenced from top left, down the left column, to the
top right, and down the right column. The values the LEDs represent are as
follows: Program mode
=
128 decimal ($80 hexadecimal; Setup mode
=
64 ($40);
Quick Access mode
=
32 ($20); Effects mode
=
16 ($10); MIDI mode
=
8 ($08);
Master mode
=
4 ($04); Song mode
=
2 ($02); Disk mode
=
1 ($01). See Figure
4.ll.
25