Sharp CE-E, Service Manual

Page: 6 / 16

-
CE-1600E
9-2. Centronics interface
Fig. M54514AP driver equivalent circuit
Seven above circuits are implemented on a single chip of the driver
and two chips are used in the CE-1600E. Among 14 circuits (7
circuitsx2), 8 circuits are used lor data output and 4 tor STROBE
and INIT outputs, 1 for BUSY input, and remaining one circuit is not
used.
G)
Data output
From gate array ~
~OW
®
STROBE, INIT outputs
Because both signals are active low and the gate array goes
high during reset, a non-inversion butler is provided between
port and Centronics interface.
From gate array
--'M---l
WLOW
:-, r,
I
L..J ,
CE-1600E___.) LO",,' ~
To
pnnteer
To prevent malfunction at power on and oft, a pull~ resistor is
inserted to PB6N.
®
BUSY input
When the printer is not in connection, a pullup resistor is used
to set it in the busy state. A diode is used to prevent intrusion
01the power supply when oft.
,
I
,
To printer ___.)
I
I
I
~CE-1600E
9-3. Power supply circuit
VP, VBAT circuit
AC aoapter, __/jl
D2
D3
about 9.4V
N
N
• •
....Vp
SUM3x5 ,
r ,
,
D4
L-.{>I
J
.. VBAT
D6
{>!
Dl,D5,D6 nOOO3
D2,D3,D4
1O,EIN
01: For prevention of counter current flow from the battery to
the adapter.
D2, 03: To drop the voltage from the adapter to the f10PPVdiskdrive
voltage, 7.5V, maximum.
04: For prevention 01 counter current f10w from VßAT (main
unit) to VP (Iloppy disk).
05, D6: For prevention 01counter current flow to the battery when
the adapter is in use.
-~-
CE-1600E
PC-16 0 0
(*u: )
VC
VCC4-~----+--------------'
-=-UM-3
- (X4)
ifr
After the batlery power supply is ORed with VBAT of th
CE-1600E, VCC is regulated to 4.7V before supplied to th
CE-1600P. (See the figure below.)
When the main power is off, VCC is not supplied.
9-4. Low battery detect circuit
CD
VP low banery detect circuit
V OUT
MN 1280
output characteristics
The MN1280Q low batlery detect IC is used in the VP low low
batlery detect circuit. (Rank Q=VDL: 3.8-4.1V)
VOUT must be inverted in the comparator before supplied to the
gate array.
Vp
vo:
MN1280Q
> •
To gate array
PAI I
VOUT
1.1-2.4V
®
VP, VCC comparator circuit
As it is necessary to satisfy the condition of VP>VCC+01V
in
order to 5VC inside the CE-1600F, the condition is monitored
by means 01the comparator.
VP
100KO
>
t
To gate array
PA21
5KO
(Potentiometer adjusting method)
1) Add 4.5 to 5V to the VCC pad.
2) Add VCC+O.1V to the VP pad.
3) Rotate VR counterclockwise and set the LB test pad vohage to OV.
4) Slowly rotate VR clockwise and stop it when the LB test pad
voltage came to be VCC. (See the parts and signal description
lor the location 01test pad.)