AMSTRAD CPC6128 User manual

M
CPC6128
MICROCOMPUTER
CTM644
COLOUR MONITOR
GT65 GREEN MONITOR
SERVICE MANUAL
PRICE: £8.00

CONTENTS Page
Safety Test 2
Keyboard Exploded View and Parts List 3
CPC61 28 Basic Hardware Analysis 4
Function Diagrams 5
Function Diagrams 6
Software Errors 7
Diagnostic Flow Chart 8,9,10,11
Alignment Checks 12,1 3,1 4,1
5
CPC6128 Main PCB 16,17,18
CPC61 28 CPU Circuit Diagram 19,20
Electrical Parts List 21
GT65 Exploded View and Cabinet Parts List 22
GT65 Circuit Diagram and Voltages 23
GT65 Main PCB and Alignment Instructions 24
GT65 Electrical Parts List 25
CTM644 Cabinet Drawing and Electrical Parts List 26
CTM644 Electrical Parts List and Alignment Instructions 27
CTM644 Electrical Parts List and Voltages 28
CTM644 Circuit Diagram 29,30
Main PCB 31,32
Interface Circuit Diagram 33,34
Disc Control Circuit Diagram 35,36
Cassette Control Circuit Diagram 36
Mechanism and Mechanical Replacements 37
Technical Specification Back page
SAFETY TEST
All Monitors are safety tested to the following specifications.
1). Flash Test
Test at 3kV between the live and neutral of the mains lead joined together and
and ALL accessible metal points on the exterior of the set.
2). Insulation Resistance Test
Test between the live and neutral of the mains lead joined together and ALL
accessible metal points on the exterior of the set to show aresistance of at
least 4Mohm.
If after servicing there is any doubt about continued electrical safety the above
tests should be carried out.
AMSTRAD CONSUMER ELECTRONICS PLC
BRENTWOOD HOUSE, 169 KINGS ROAD, BRENTWOOD, ESSEX CM14 4EF.
Telephone: Brentwood [phone]. Telex: 995417 AMSELE G.

KEYBOARD EXPLODED VIEW
KEYBOARD PARTS LIST
Sym Description Part No.
1Cabinet Top Assembly 170855
2Frame FDD 170856
3Knob Volume 170806
4Cabinet Bottom 170857
5Keyboard Assembly ESU-244 170858
6Compact Floppy Disc Drive
EME-155 190005
7Volume Rotary K1 21 L0Z0T-20KB 170807
8Jack RCA 3.5 HSJ 1061 -01 -440 170022
9User Port Socket HXC0730-01 -01 170023
10 Jack DIN TCS4450-01-101 170850
11 Jack DC HEC0470-01-630 170024
12 Jack DIN TCS4460-01-1011 170025
13 Cord DC 14550401 170822
14 RelayG4S-1112P-1-B-19 170123
15 Cord Connector 8W6Q004A 170862
16 Speaker C040K01 K2451 170124

/connect to
(240v ac mains CPC6128 —BASIC
HARDWARE ANALYSIS
CHECK KEYBOARD PCB
FOR SIGNS OF ABUSE:
-CRACKS
-LIQUID SPILLAGE
-DISTORTED MOUNTING
CHECK CONNECTOR LEAD
AND TERMINATION
IF UNIT STILL
FAULTLY SEEK
SPECIALIST
ADVICE
FAULTY AUDIO AMP OR SPEAKER
FAULTY VOLUME CONTROL
FAULTY AUDIO CONNECTOR
PLUG/SOCKET
FAULTY AY- 3- 8192 SOUND IC
FAULTY VIDEO CONNECTOR
FAULTY CABLE ASSY
FAULTY ULA
FAULTY PCB
CHECK FAULTY MONITOR
#CABLE TERMINATION
#INTERNAL CONNECTORS
#BRIGHTNESS CONTROL
FAULTY ULA
Z80A
6845
CRYSTAL
RAM
Full diagnostic tests on the C.P.U. can be carried out using the Amstrad RP2 Test Pack.
Please contact Amstrad PLC for information on same.

FUNCTION DIAGRAMS
ICII4 VCC SQ SD ID 70 60 SD SD 50
mmm m pfi p?i un mmENABLE
ENAB
QES\Tf0E
&,OF
=C
tal 13 2>| \D
o°fa| ,0£
J
§0f
o"ca
Tjrmmmmmijwmw
OUTPUT IB ID 2D 20 30 3D 4D 40 GND
C0NR0L
ICIIS Vcc 2G IYI 2A4 IY2 2A3 IY3 2A2 IY4 2AI
wLlLlLlLlLllLllllJLllL£j
IQIAI 2Y4 IA2 2Y3 IA3 2Y2 IA4 2YI GND
ICI04.I05 STROBE ADATA INPUT'S OUTPUT
ICI09.II3 VCC 2G SELECT ^" 'lT"lf ^J-3
V
^2C3 2C2 2CI 2C0 21
^
A
Hi hi lu mHi ill LiJ m
STROBE B''OUTPUT
IG SELECT DATA INPUTS IY GND
VCC 4B 4A 4Y 3B 3A3Y
m m f«i mmm m
uill ill Hi mHi LzJ
IA IB IY 2A 2B 2Y GND
ICIOI INPUTS
VCC ABcD' Isz_
mus] m m mmmrti
j
ABCD
BCD-TO-DECIMAL
I23 4 5 5 7 8_1
X
I4J L4J 3j I4J L^J 1_|J L^J l«j
OUTPUTS GND
ICII2 Vcc 4B 4A 4Y 3B 3A 3Y
[mi mi/Fi [77i poi ri m
111 111 LU 111 111 LiJ IU
IA IB IY 2A 2B 2Y GND
ICI06 VCC 30 8D ID 10 60 6D SD 50 CLOCK
[^[7jn[7F|[77l|76l[75l [771 [7J1[7J1 1771
11 lil 11 LI ill LI LI II lAj n
LEAR IQ ID 2D 20 JO 3D 4D 40 GND
VCC 6A 6Y 5A 5Y 4A 4Y
4Ui3Uig_fiTlJioU9lJ8l
iinin3n4j-i5nif
TiiliJlkliJlkJIillzf
1A 1Y „2A 2Y 3A 3Y GND

FUNCTION FOR AMICROCOMPUTER AND IC'S
CPC6128 FUNCTION DIAGRAMS
Vss E
RES H
LPSTE E
MAC E
MAI E
MA2 E
MA3 E
MA4 K
MAS E
MA 6I
MA7 E
MAS 1
MAI E
MAIL E
MA II E
MA 12 EI
MA 13 Ez
DISPTMG l»
CUDISP EI
Vcc ]20
VSYNC
ADRESS
BUS
I/O
PORTB
w\~Aio
H-X!
ZZH?
M~Ae
1-/15
EH<
IHi
E'Al
M~Ao.
^~GND
M~RFSH ]SYSTEM
^mJCONTROL
M^REsTt^-cpu
_j ncoci CONTROL
x\~nusRa-~i—cpu
E-MTtjJ ^CONTROL
ZJi^BUSAK -
22\~WR)SYSTEM
KEYBOARD SW.
ANALOG
CHANNEL CEl
rEST 1E
Vcc
ANALOG
CHANNEL B
ANALOG
CHANNAL A
E
E
E
Vss EC
10A? E
10As E
10As E
10A4 E
10A3 E
10A2 E
lOAl EI
lOAo E
ICI02
CONNCTOR NO.
234
O
[7"
DEL
"T,
7~
7~~
CLR
7~
71
COPE
S7
P9
ESC
7~
i
®
ENTE
R
V
TAB
7"
7"
7~
T
Tl
T
TSHIF
T
T
CAPS
LOCK
7
\
7"
7
ENTE
R
V
V
SPACE
KEY
CTRL
T-0/9
RESET C
RD C
WR C
CS C
AC
DB C
DBi C
DB 2C
DB3C
DB4C
DB5C
DB6C
DB7C
DROC
DACKC
TCC
IDXC
INTC
CLKC
GNDC
i<^—
2
3
4
5
6
7
10 765A
11
12
13
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
3VCC
3RW/SEEK
3LCT/DIR
3FR/STP
JHDL
3RDY
3WP/TS
3FLT/TRc
DPS
DPS!
3WDA
DUS
3US!
•3 HD
3MFM
,3 WE
DVCO
3RD
]RDW
DWCK

Software Errors
If adrive fault is reported the fault may be asoftware problem. Before investigating the drive
please carry out the following checks to ensure it is not asoftware problem.
Detection and Correction of "Soft Errors"
Soft errors are usually caused by the following reasons.
1) Random external noise of several usee or less.
2) Minute off-tracking and shifting of write timing that are not detected during the write operation
which can cause the soft error during the read.
To remedy such soft errors, take the following procedures at the controller side.
1) Repetitive reading on the track by 10 times or more until the data is restored.
2) When the data is not restored by step 1, access the head to the adjacent track in the same
direction as move previously, and thereafter return the head to the original track.
3) Repeat the step 1.
4) If the data is not restored by the above steps, the error cannot be remedied
Write Error
When an error is caused during the write operation, the error is usually detected during the next
rotation through the read operation called "Write check".
To correct the error, repeat the write operation again and carry out the Write check.
If the result is still incorrect even after the write operation is repeated more than 10 times, either
the disc or the drive are working incorrectly. To find out the trouble source, carry out the read
operations with another track. Should the error still be found, change the disk and repeat the above
procedures. Should error still be found, the drive should be considered defective. If the error is
removed, the original disk must be defective. Discard it.
Seek Error
1) Step motor or step motor drive circuit is defective.
2) The torque of the carriage is not correct.
Restoration procedures from the seek error.
Make the re-calibration to the track OO. Then, carry out the re-seek to the original track.
Notes:
1) Always ensure the head is clean.
2) Index/Sector Factor (Ready Defect)
As the unit has Optional Read Output
It is normally not ready until 2revolutions are made after the disk insertion.

Diagnostic
Flow Chart
This chart must be used in conjunction with
the Alignment Procedures.
This chart is for information only and
does not guarantee an exact diagnosis.
For warranty purposes any faulty drive
mechanism must be returned to Amstrad
for replacement. Service Agents should
not attempt any repairs on the mechanism
or to its P.C.B. P.No. 30001.
3-A
Motor rotation
Read error
Write error
Interchange-
ability error
Disk Drive O.K.

3-B
FLOW CHART (cont)
Replace motor Replace drive

3-C FLOW CHART (cont)
Read error
Test with disk
EME- CF2
Replace disk
(inspect by
drive)
Replace drive
Replace drive
Replace drive
Replace
head assembly
Replace drive
Replace
TROO sensor
10