Korg EX-800 Service Manual

9. CHECK AND ADJUSTMENT PROCEDURE
ADJUSTMENT PROCEDURE
Use the POLY-800 for check and adjustment of the EX-800.
Connections are as shown here. Use a 5-pin DIN cable less
than 15m long for connection.
Note: The EX-800 MIDI OUT terminal is for memory
dump to a personal computer (via a MIDI interface).
Caution: This product has been thoroughly adjusted at the
factory before shipment. Therefore do not adjust anything
other than those VRs required for servicing.
BEFORE making any calibration adjustments, Be sure test
data is loaded into EX-800.
The following setting chart shows the program data used
for service testing. After inputting the data, save it on tape
for future time saving convenience.
PROGRAM no. 11 (noise level):
PROGRAM no. 12 (master oscillator):
1. Power supply circuit (KLM-596, circuit no. 15):
Be sure that the specified AC adapter is being used: 9V,
300mA,
1) +5V check and adjustment:
Use DVM (digital voltmeter) to check KLM-596 connector
CN6 Pin 6 and confirm +5V *(±0.005V). Adjust VR1 if
necessary.
2) -5V check:
Use DVM to check KLM-596 connector CN6 Pin 8 and
confirm -5V (within -4.7V - -5.7V)
2. D/A converter check and adjustment (KLM-596, circuit
No. 12):
1) Select program No.12
2) Set joystick bend control of POLY-800 at center posi
tion: BEND INT to 10
3) Connect DVM to KLM-596 IC10 (TL062) Pin 7 and
confirm 2.001V ±0.005V. Adjust VR4 if necessary.
Also confirm:
3.984V ±0.005V for an upward pitch bend and
0.024V ±0.005V for a downward pitch bend.
Note: Adjustment is easiest in the joystick circuit although
the idea is to obtain a 4V output from IC 38 (TL062) by
adjusting the D/A converter when IC 81C55 port A output
is all high.
3. Noise level check and adjustment:
1) Select program no. 11.
2) Depress any single key of POLY-800.
3) Connect oscilloscope to KLM-596 CN6A 1 pin and con
firm noise level of 0.3Vp-p (± 20%).
4) Adjust VR3 if necessary.
-17-
Scan by Manual Manor
http://www.markglinsky.com/ManualManor.html

Korg EX-800 Specifications

General

Brand	Korg
Model	EX-800
Category	Synthesizer
Language	English