Service manual

<Dot display>
Fig. 9-6
IMPORTANT:
The CKDC6 lines are not high voltage resistive ports. Damage may
occur to the CKDC6 if lines are shorted carelessly when using oscillo-
scope probes.
• Dot matrix tube
A 4-bit binary output signals (ST0-ST3) from CDKC6 are converted
into the digit drive signal (DG0-DG11) in the M66004FP.
<Dot display control>
The CKDC6 controls the character segment (5 x 7) and the indicator
of the dot display by using the controller (M66004FP) for dot display
control.
1 M66004FP/Dot display control signal
Signal
name
Contents Pin/Remark
DSO
Serial data output signal
for M66004FP
C-MOS pin
DSCK
Serial shift clock output
signal for M66004FP
C-MOS pin.
Requires to be pulled up
DCS
Chip select output signal
for M66004FP
C-MOS pin
10. Power supply circuit
Fig. 10-1
+24V: Printer, solenoid power
+5V: VCC (Logic power)
VBAT: Battery charge
–32V: Display tube power
VF1, VF2: Display tube power (AC)
VRAM: Battery back-uped power
VCKDC: CKDC-4 Back-up power
11. Switching regulator circuit
Fig. 11-1
By switching VIN (+28.8V) by the transistor TR1 within the STR2024,
DC+24V supply is obtained through the LC network. Stable +24V is
obtained by controlling on/off duty of TR1.
ION: Current when TR1 is on.
IOFF: Current when TR1 is off.
ENST
ST0~ST3
19.1µ s
DGn
"h" th digit
display
DGn+1
Display off
D0~D35
"h" th didit display pattern (h+1) th didit display pattern
17.2µ s
(h+1) th digit display
D0 D1 D2 D3 D4
D5 D6 D7 D8 D9
D10 D11 D12 D13 D14
D15 D16 D17 D18 D19
D20 D21 D22 D23 D24
D25 D26 D27 D28 D29
D30 D31 D32 D33 D34
D35
: Indicator
Noise filter
DC-DC
Converter
circuit
Battery
circuit
VRAMP
+5V
-32V
VF1/VF2
F1
F2
Switching
regulator
(STR2024)
+24V
+
-
~
~
VCKDC
VBAT
VIN
+28.8V
+
4700µ
63V
5
VIN
TR1
Refer-
ence
voltage
circuit
3
2
4
1
L1 220µ H
IOFF
ION
+24V
Load
C2
2200µ F
35V
R2
STR2024
– 29 –