Olivetti CMS 140 B euro, Service Manual

Page: 37 / 55

686770R Service Manual 5-1
5. BLOCK STRUCTURE CHART
As illustrated in the Chapter 6.
5.1 CIRCUITRY
Functions in each circuit is explained below block by
block.
• Block A: Display Control
LCD driver is included in the main CPU and is
directly driven by ports below.
* COM 0 - COM 1 - COM 2
* SEG 0 - SEG 25 - SEG 32 - SEG 33
LCDs are 1/3 duty,1/2bias.
• Block B: Scan Signal for Key switch, Mode
switch and Paper feed key:
Scan Signal Output Ports: from ports P07 - P12-
P60 and P61 , by High-active scan output.
Key switch: when P54 - P57 are depressed, they
are accepted as return input of the key matrix.
Mode lock switch and Feed key: P53 is read in as
a return input.
* To prevent input errors caused by chattering,
data will be read twice before accomplishing key
input.
• Block E: Buzzer:
When Port P45 gets high, oscillating signals pro-
grammed at NAND gate make transistor 2SA2603
on/off and make the buzzer buzz.
• Block F: Reset Circuit:
Reset IC works to reset main CPU.
NOTE:
1) Reset does not work when backup function is
working.
2) CPU needs to be reset at the first setting up,
otherwise normal operation would be hindered.
To secure normal operation, first install opera-
tion batteries worth OFF mode. Next turn the
key to REG1 mode, then place memory backup
batteries.
• Block G: Black-Out Detection Signal:
Blackout signal is generated when voltage in Vcc
line drops to 3.0 V. This signal gets “low” at the
time of blackout and is transferred to Port 42 for
CPU to dispose it. Once blackout is detected, X
IN halts and only X CIN oscillates to turn the cash
register for electric consumption mode. Backup
currency at this time is about 10-40 uA.
• Block H: Printer Control:
• Motor Drive: P51 (low active)
• Printing Trigger: P50 (low active)
• Timing Signal: P43
• Reset: P44
NOTE:
Waveforms for timing signals and reset signals
are shaped by flip-flop at NAND gate.
• Block I: Circuitry:
This machine operates both by dry batteries and
with use of AC adaptor. Inserting an adaptor jack
automatically disconnect the battery circuit.
Voltage at each power line is as follows (at rated
voltage input).
VBB: 6.0 V (with backup)
Vcc: 6.0 V
Vprm: 6.0 V (when printer is not working)
V BB / V cc are provided via a stable circuit that
uses 3-terminal regulator (S81250HG).