GEM Equinox Pro, Service Manual

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Test Procedure and Adjustment
The procedures that follow must be executed subsequently in
the order specified.
These procedures are not intended to repair a fault but only to
check the correct instrument operations after a repairing execu-
tion.
Test Instruments
þ Dual trace oscilloscope
þ Digital Multimeter
Accessories
þ 2 x 4Mbyte SIMM DRAM modules.
þ 1 Vocal Processor Kit.
þ 1 3.5" Formatted Diskette.
þ Read/write JOMEGA ZIP SCSI device.
þ RS232 loopback (terminal 1-2 and 3-5 shorted)
þ 2 jack-jack cables with a resistor divider inside plugs (10K/
82ohm).
Note: To check completely the keyboard are necessaries all the
optional accessories installed.
Setup
Install all the optional accessories: the Vocal processor kits, the
2 SIMM modules and insert the diskette into 3.5" disk drive.
Set the jumpers on CPU board as follow: set J1 at position B,
leave the jumper J2 on position 8MB.
Set the JP1 and JP2 jumpers on Supply or Mixer board at position
A (Vocal Processor Installed).
Connect the R and L outputs to the MIC/LINE inputs using the
appropriate cable.
Connect the external JOMEGA ZIP SCSI device to the SCSI
socket.
Plug the RS232 loopback into the socket.
Checks and Adjustments
þ
Aftertouch
To adjust the keyboard aftertouch locate the VR1 trimmer on
CPU board, connect the scope CH1 probe tip to its center
terminal, probe clip connected at ground, adjust VR1 to obtain
an excursion from 0 to 5V every time a note key is pressed with
different pressure, or to obtain a better adjustment follow the
instructions on ADJUSTMENT TABLE (page 6).
þ
MIDI, RS232 and RS422 mode
Press MIDI, MASTER (F3), PC I/O (F3), set PC1 with DIAL and
press ENTER, set LOCAL to OFF (F1), verify that the keyboard
plays thru RS232 by unplugging and re-inserting the RS232
loopback into the socket.
Press MIDI and F3 twice, rotate the DIAL to set “MACINTOSH”,
check the 1MHz clock appear on pin 1 of COMPUTER socket (use
the second probe tip to do that).
þ
Panel Key and Led
Press SYSTEM, OTHER (F4), INFO (F1) and F4 the display show
a warning message: press ENTER and PANEL (F3) and then press
all the panel buttons checking their operation on display, at the
same time every led of pressed button must light up, except
DISK led.
þ
Pitch Bend and Modulation Wheels
Rotate the Modulation wheel verifying the excursion displayed,
it ranges from 0 to 127.
Rotate the Pitch Bender wheel verifying the excursion displayed,
it ranges from 0 to 127 with 64 on center position, a slightly
difference may be adjusted by VR11 on Controls panel board, a
greater difference may be adjusted repositioning the knob or the
potentiometer.
Press ENTER and ESCAPE simultaneously to return to HARD-
WARE test menu.
þ
Memories and Optional Accessories
Press DEVICE (F1), the instrument self-test check subsequently
the follow devices: SIMM modules (VDRAM), 8Mbyte sample
dram (BDRAM), 3.5" disk drive (FD), SCSI interface (SCSI) and
hard disk (HD) marking with “pass” all devices checked success-
fully, with “np” all devices not present, with “fault” all device
defective. Theoretically all test must be passed, if you have a
mistake on a device re-check its installation.
Press ENTER if necessary.
þ
Inputs, Dsp and Vocal Processor
Put MASTER - INPUT - LEVEL sliders to maximum position and
rotate full clockwise GAIN1 and GAIN2 potentiometer located on
the rear side.
Measure a sinusoidal signal at 4Vpp on OUT 1 and OUT 2 outputs
sockets (the 1KHz tone gets out OUT R and L, re-input thru MIC
1 and 2 by the appropriate cable, pass thru DSPs and finally get
out from OUT 1 and 2).
Turn off the signal by means SIGNAL (F4).
þ
Noise level
Turn off the instrument, disconnect the signal cable, wait at least
30 seconds, turn on again the keyboard and check the noise level
is acceptable (if not verify the insulation between electrical and
chassis ground is at least 40Kohms).
þ
Data Hold
Press SYSTEM, OTHER (F4), INFO (F1), F4 , ENTER and DHOLD
(F2) and then wait until the display show PASS.
Turn off the keyboard and then remove not included optional kits
(the EQUINOX PRO version is equipped without Vocal Processor
and SIMM Modules), restore the jumpers positions: J1 to A, JP1
& 2 to B. Turn on again the instrument and verify, repeating the
test, that only BDRAM, SCSI and HD pass.
þ
Final Check
Verify the keyboard correct operation playing something on it,
and finally launch the Sounds sequence pressing PROGRAM,
SHUFFLE (F4), MAKE (F1). When it is finished you have tested
the keyboard.
þ
Reliability Check
Before reassembling the instrument and before deliver it to the
user, it is a goal verify its reliability:
To do that switch it off, or leaving it switched on but operating
with greatest caution, carefully shake the boards and connec-
tions inside it using an insulated tool (for example the handle of
the screwdriver) to find wrong contacts and so on.
Turn on the instrument and verify that it operates correctly
repeating the Final Check.
Disconnect the instrument from the mains, reassemble it and
shake it carefully without causing aesthetics damages, re-
connect it to the mains, turn on and re-check its functionality,
finally leave it switched on for a long time verifing its function-
ality occasionnally.