IC-102
Pin 1 is limiter output to IC-103's integrator, If light is
above 1/2000 exposure, pin ! goes high to set exposure
time to 1/2000,
Pin 2 has no connection,
Pin 3 is IC-103's integrator input to CP-M. Vcc through a
1000 ohm probe should cause fast speed in "Auto." See
scope trace,
Pins 4, 5 switch integration capacitors into IC-103's
circuit. Normally low.
Pin 6 is ground.
Pin 7 is BV input from IC-103. l,5v to 1.7v, I8mv/Ev,
Pin 8 connects to pin 15, IC-103; SPD anode. Typical
voltage is 1.8v.
Pins 9 and 10 are integration capacitor control code from
CPU. See pins 7 and 8, IC-101.
Pins 11, 12, 13 are decoding control inputs from CPU.
See scope traces.
Pins 15 and 16 are battery check mode inputs from pins 1, 2,
IC-101.
Pins 17 and 18 are MG-l's control signals from the CPU.
B- through a 1000 ohm probe should cause M-l to
"click."
Pin 19 is the Piczo input from CPU.
Pin 20 is integrator compensation input from CPU.
Pins 21 and 22 are mode control from CPU, (Pins 56, 55,
IC-101.)
Pin 23 is signal from CPU to power LCD.
Pin 24 is "power on" signal from IC-101. Should go high
when release is pressed one-half stroke.
Pin 25 is CLK in.
Pin 26 is B-,
Pin 27 is reset signal to IC-101 when battery voltage
comes up to 2.90v,
Pins 28 to 35 are DAC data from IC-101. See scope
traces.
Pin 36 is input signal for LED. Vcc through a 1000 ohm
probe should light LED.
Pin 37 is trigger output to CPU.
Pin 38 is Ev data out to CPU. See scope trace,
Pins 39 and 40 are outputs to CPU to indicate flash is on
(40) and charged (39). Pin 39 voltage should fall from
near Vcc to near zero when flash charges. (B- through
1000 ohm probe to pin 48),
Pin 41 is Self-Timer LED drive signal to Q-40I. Voltage
near zero to turn on LED.
Pin 42 is the "go" signal to CPU if battery voltage is above
2.65v. Series of low pulses stop when battery voltage is
low.
Pin 43 connects to C-105.
Pin 44 is integration current charging C-104 for
"Manual" and "Spot" shutter timing. See scope trace.
Vcc through a 1000 ohm probe should result in fast
manual speed.
OLYMPUS OM-4, PAGE 7
Summary of Contents for OM-4
Page 22: ...OLYMPUS OM 4 PAGE 22...
