Korg EX-800 Service Manual

22) Detune circuit:
Lowers frequency by thinning out clock pulses.
23) Tape interface output circuit.
24) CV circuit:
Performs time division output and S/H on CV for VCF and
master oscillator.
25) 6-bit latch circuit:
A 6-bit control output circuit with 2 bits for detune, 2 bits
for DCO waveform switching, 1 bit for A/D converter, X-Y
switching, and 1 bit for noise gate control.
26) 6-bit latch circuit:
A 6-bit control output circuit with 5 bits for S/H control
and 1 bit for chorus on/off switching.
27) VCA + VCF circuit:
The IC1 (NJM2069) has three internal VCAs and one
internal 24dB/oct VCF (LPF). SIG1 and SIG2 respectively
receive mixed DC01 and DC02 inputs from the TG;
LEVEL1 and LEVEL2 are control input terminals.
The other VCA is for noise only. The 9pin (VCA LIN IN) is
its control terminal.
MG, EG INT and CUTOFF, KBD TRACK are controlled
separately and input to VCF LOG.
See REFERENCE DATA for details.
31) Waveform synthesis circuit:
Using the TG's various foot outputs (16', 8', 4', and 2'),
this produces 2-waveforms, one by addition on a 1 = 1 = 1 = 1
basis and the other using the ratio 1 = 1/2=1/4=1/8.
The block resistor BR5 (RKC 1/8 B4 33K) is made up of
four 1/8W 33k resistors (1 = 1 = 1 = 1). BR6 (RMO0470) is
10K ohms using R, 2R, 4R, 8R (1 = 1/2=1/4=1/8).
32) TG (Tone Generator):
An IC having eight sets of dividers and VCAs. See
REFERENCE DATA for details.
KLM-598,614
KLM-598 consists of the chorus circuit and headphone amp
circuit. The VCF output signal transits noise gate F1
(2SK381) and is input to compressor IC3 (NE570); then
IC4 (M5224P) detects the envelope.
The clock generator circuit which drives the BBD IC makes
IC7 (M5224P) generate a triangle wave which comparator
IC8 (393) converts to a sawtooth wave with a change of
pitch for a more natural chorus effect.
F2 (2SK381B) at the output is an FET for chorus on/off
switching.
KLM-614 includes the panel section LED display and
switch matrix circuitry.
28) Analog switch circuit:
Performs DCO waveform switching and joystick A/D con
verter input switching.
29) Noise generator.
30) MIDI interface circuit:
This is a standard type MIDI interface circuit employing
the MIDI interface IC26 (ACIA63B50) and high processing
speed photocoupler PC-1. (PC-900)
D22 is used to prevent destruction of the photocoupler
LED in case a reverse voltage is applied. R119 (220 ohm)
and R121 (220 ohm) resistors are for prevention of damage
in case of excessive current.
The circuit is designed to provide a data transmission rate
of 31.25 k baud(±1%).
-15-
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Korg EX-800 Specifications

General

Brand	Korg
Model	EX-800
Category	Synthesizer
Language	English