Sharp MZ-80A User manual

,
SHARP
PDSM9S1 01 O-MZ
Personal Computer
Z-BOA
IFEATURESI
• The MZ-80A is a full -fledged personal microcomputer equipped with B·blt microprocessor (l-80)
and it can meet a variety of applications like hobbies, educations, office works, controls (of
apparatus in every industrial fieldl, etc .
• It is a compact desk - top type, itself a simp lified unit including CPU board, CRT display, casse tt e
tape recorder and keyboard all together .
• The keyboard touch will satisfy professional operators, and numerical input keys are provided.
• Speaker (3 octaves) and clock function are built in.
• A video RAM of 2K bytes is provided to facilitate edition aided by CAT display.
•
• Memory extensions is allowed up to 4BK bytes in the board.
• Four types of I/O cards for peripherals such as a floppy disk and printer ean be added by optional
extension units .
•
•
SHARP CORPORATION
,

Contents-------------
Specifications ...............................................•.... 1
Trouble shooting guide .............................. : . . . . . . • . . . . • . . .. 3
CPU board section ...................... . . . . • . . . . . . . . . . . . . . . . . . • . .. 4
Display section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11
Cassette tape recorder section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15
Power supply
section. . . . . . . . . . . . . . . . . . . . . . ............. '. . . . . . . . . . . .. 19
Circuit diagram and printed wiring board
.................................. 21
Disassembled view ................................................. 35
Packing method ....................................•............. , 39
Replacement parts list. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 40
Caution in Service
it Maintain the safety and protecting ability of the apparatus
after
serVice.
it High voltage shall not be rised to excess voltage so as to prevent
this apparatus from the extra X-ray radiation.

I
• General
CPU Z-80 Clock
function
Built in
Memory ROM; 4K bytes (Monitor) Music
function
Built in
ROM; 2K bytes (character generator) Editor Cursor
control; "up", "down",
RAM; 32K bytes (dynamic RAM)
function
"right", "left",
Memory extension; 48K bytes
"home", "cleary home"
(max.) Edit key, Delete key
RAM; 2K bytes (video RAM) Roll
up and roll down
Display
9" CRT (green display) Power supply AC
220V ± 10%, 50 Hz
8 x 8 dot matrix. AC
240V ± 10%,50 Hz
Characters; 1000
(40 characters x 25 lines) Power
Cassette Standard
audio cassette tape
consumption
Approx.36W
Data transfer speed; 1200 bits/sec. Temperature Operating
temp.; O°C to 35°C
Data transfer system; SHARP PWM
Storage temp.; _15°C to 60°C
Sound output
400mW (max.) Humidity Lower
than 80° during operation
Keys layout Number;
73 keys Weight Approx. 10kg
ASCII standard Width;
440mm
(alphabet capital letter, figures), Dimensions Depth;
480mm
Small letter, Graphic, 10 Numerical Height;
260mm
• CPU Board Section
CPU Z·80; 1 pc Programmable
8253
1 pc
ROM
Monitor; 1 pc (4K bytes)
counter
Character generator; 1 pc (2K bytes)
Programmable
RAM
Standard; peripheral
8255
1 pc
16K
dynamic RAM; 16 pcs. interface
(32K bytes)
Video RAM; 1 pc
(2K bytes)
• Power Supply Section
Input AC 220V ±10%, 50Hz
AC 240V ±10%, 50Hz
Output DC12V
DC5V
DC-5V
-1-

• Display Section
I. General specifications
11. Electrical specifications
Size
9"
Video output
4OVp-p standard (35Vp-p limit)
Frequency 60Hz (vertical), 15.7SkHz (horizontal) Resolution Horizontal These patterns
of the
11
left in the center ofthe
picture must be clear.
Power source
DC 12V, 1.lA ±10% Non-linearity Horizontal;
±8% (±14% max.)
distortion Vertical;
±8% (±12% max.)
Picture tube Cl0M36P31
or 2728B31; Geometrical Pincushion dist.;
1% (2% max.)
9"90° deflection
explosion proof type distortion Barrel dist.; 1
% (2% max.)
Trapezoidal dist.;
1% (2% max.)
Heater; 12V. 7SmA Parallelogram dist.; 10 (2.So max.)
IC
2 pes.
High voltage Zero beam; 11.0kV
(10.0kV, min.,
Transistor 7 pes. 12.0kV, max.)
Diode 13 pes. Power supply DC12.0V, 1.0SA (1.2A max.)
Working range 12V ±10%
Sound output
400mW max. (440 Hz)
Scan size Horizontal; 10% (lS% max.)
Speaker Bem, round dynamic type Vertical; 10% (lS% max.)
(320)
Horizontal
Control knob Volume lock-in range ±300
Hz (±100Hz limit)
Brightness Vertical
lock-in raniJe
-12 Hz (-6 Hz limit)
Working Audio
440 Hz (OdB)
-10°C to SOOC
friquency
-lOdB ±4dB at 100 Hz
temperature characteristic
-12dB ±4dB at 10kHz
. Sound maxi- 400mW
at 440 Hz
mum output
• Cassette tape recorder Section
System
PWM recording Biasing
DC system
Power source
SV ±0.25V (rated) Erasing
DC system
Rated amperage Wait; 2mA Playback 1m sec.
to SOO/-l sec. (standard)
Record; 70mA (TEAC test tape) sensitivity
Playback; 7mA (TEAC test tape) Input level Below 0.4V
("l")
Semiconduc· 4 transistors Over 2.0V ("H")
tors 1
IC
Input Over
10kll (record jack)
4 diodes impedance
Applied tape From C30
to C120 Output
level Below O.4V ("l")
Over 2.0V ("H")
Tape speed 4.7S cm/sec. Working
-10°C to SOoC
Track 2-track monaural
type
temperature
Motor Electronic governor motor (12V) Storage -2S
oC to 70°C
temperature
NOTE Specifications and appearance are subject to change without prior notice for improvement. In such
a case, the explanation here may be a little different from the product.
-2-

The machine comprises five main units, CPU board, display, cassette tape recorder, keyboard, and power supply
circuits. For a quick solution to most operating difficulties, first consult the chart below to find which section of
the machine is subjected to the trouble, and next to do the checkings according to more detailed instructions given in
the succeeding pages.
Start
Switch on
Yes
Yes
I
s the cassette
~ecorder normal?
Yes
Yes
Yes
End
No
No
No
No
No
-3-
Check for the power
supply circuit.
Check for the CRT
display.
Check for
the cassette
recorder.
Check for the keyboard.
Check for the CPU board.

CPU BOARD SECTION
The CPU board is composed of the following six blocks. When it gets in trouble, first locate which block is
concerned with the trouble, and next try to check for its corresponding circuits; the wiring diagrams of every block
will be
shown separately.
CPU in trouble
Display
block
No
Cassette
recorder
block
Keyboard
block
Audio
block
Clock
block
No
Gets in
trouble instantly
with power
on.
No
Yes
Yes
Yes
Yes
Yes
Yes
• Checking-methods of each circuit
Check for video
RAM circuit.
Check for IC50
(8255) and its
peripheral parts.
Check for IC50
(8255) and its
peripheral parts.
Check for IC47
(8253) and its
peripheral parts.
Check for IC47
(8253) and its
peripheral parts.
Memory circuit, Reset circuit
and its peripheral parts.
1. By touching IC insulating parts by fingers:
'.: If they seem too hot by heat generation;
IQ.oi~"j:fefl~ctive'-IC load
-4-
~r(~':'\
V
;~:~.'~,
'l.~/

/
• Display Block
DO
-Bus
driver
07
-
~
-'--
--
WR-
RD
CSD
~
/
AO
I
)
A9
Who
le reversal
1. Sync. signal is not produced.
2. Video signal is not
produced.
3. Irregular display
characters
4. The display is positionally
deviated.
5. Position is correct but
characters are abnormal.
Character
h
:> Video signal
generator
~
Shift
register
<~/:.
L )
BLNK
). Sync. signal
-
I
Video
'\/'
RAM
L--
1"1
Display
~
Oscillator
V
controller
circuit
Address
selector
~
C~D
T
Block Diagram of Parts around Video RAM
Vertical sync. signal: Check for pin @ of IC20.
Horizontal sync. signal: Check for pin00f IC20.
Is V·GATE signal for pin @ of IC2 high level?
Yes; IC2
No; IC50
Is V-BLANK signal present at pin ® of IC20?
Yes; IC20
No; IC2
Is H-BLANK signal present at pin CD of IC20?
Yes; IC20, IC31
No; IC2
Does pin ® of IC8 develop video signal?
Yes; IC8
No; IC2, IC10, IC4
Check IC14,
1<;:20.
Check IC21, IC22, IC26, IC27, IC32, IC33
Check IC15 and IC16.
-5-

• Cassette recorder/Keyboard Block
PC1
D7 -\
PC5
PC4
PC3
-I
LO
In
'"
~
DO
Q)
u
-
~
e
RD c
WR
-
~
Q)
.r:
PA3
Q.
-
.;:
~
Q)
"-
Q)
:0
cs
co
PAO
E
-E
~
Al
Cl
PB7
e
-
0-
)
-
AO
RESET
PBO
r
...h
r
J,
I
1 l I I
t-'
1)
L
Motor
controller
I"
I
I
Decoder
I
1,
I
~
I
I
I
J,
L
-------,
WRITE
READ
SENSE
I
I
I
I
I Cassette
I
I
I
MOTOR I
______ -.1
------1
9
~
o
I
I
I
I
I
I
I
I Keyboard
H I
) i
A :
_______ J
Block diagram of Parts around Cassette recorder/Keyboard.
1. "LOAD" operation is
impossible.
2. "SAVE" operation is
impossible.
3. Motor doesn't rotate.
4. Motor doesn't stop.
5. Key input is ineffective.
Is output signal present at pin Q) of IC10?
Yes; IC50
No; IC10
Is output signal present at pin @ of IC50?
Yes; ICl 0
No; IC50
Is voltage at pin ® of IC39 at "Iow" level?
Yes; IC4,
01
No; IC39, IC5
Is voltage at pin ® of IC39 at "high" level?
Yes; IC4,
01
No; IC39, IC5
Check
for IC52 and IC50.

• Audio/Clock Block
RD ----;
WR---i
Programmable
counter
(8253)
"- -------------- ~-'" ------------ -------.--------~---
31.5KHz ")
_ ~ Clock function
INT J
1/2 frequency
division
I-------C> Audio output
CS ----;
A1 ------1
1-----< 2MHz
AO---L ____ ~
WR----1
CS ------1
RD-----4
Latch
Oscillator
circuit for Tempo
L--,- _____ ..4
DO
Block Diagram of Parts around Audio/Clock Block
1. Abnormal sound output
2. Clock function is abn·ormal.
--r,.,..,, __________ .. ___ ---------
Is output signal present at pin @ of IC47?
Yes; IC45, IC48
No; 1C47, IC51
Is 31.5KHz signal input to pin @ of IC47?
Yes; 1C47 (8253) and surrounding are faulty.
No; IC20 (Check if 8MHz signal is supplied to
pin @ of IC20)
-7-

~-~-~----~ ~~--~---~---~
• Memory Circuit Block
Data selector
WR
RAM block
07
DO
Memory control circuit
ROM
A15
\
A12
CPU
control Bus
AO~All DO~D7
Block Diagram of Parts around Memory Circuit
1. Reproduced picture shows
"panic".
2. Error display or
misoperation is caused
as a result of program
execution.
3. Returns to "MONITOR SA-1510".
4. Error is caused after
a long operation.
Check for the following:
ROM, IC46, CG, IC13 (CPU) and surrounding circuit
Address bus line
Data bus line
Control line
RAM (by using RAM checker),
RAM check
RAM check
RAM check
~8~