AMSTRAD CPC664 User manual

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CPC664
MICROCOMPUTER
CTM644
COLOUR MONITOR
GT65 GREEN MONITOR
SERVICE MANUAL
PRICE: £8.00

CONTENTS Page
Safety Test 2
Keyboard Exploded View and Parts List 3
CPC664 Basic Hardware Analysis 4
Function Diagrams 5
Function Diagrams 6
Software Errors 7
Diagnostic Flow Chart 8,9,10,1
1
Alignment Checks 12,13,14,15
CPC664 Main PCB 16,17,18
CPC664 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 27
Instructions
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
Syrr Description Part No.
1Cabinet Top Assembly 170801
2Keyboard Assembly. R-562001 170802
3LED SLP-145B 170005
4Angle Driver Left 170803
5Angle Driver Right 170804
6Compact Floppy Disk Drive
EME-150A 190005
7Knob Volume 170806
8Volume Rotary K121 L0Z0T-20KB 170807
9Angle Power Switch 170808
10 Switch Power On/Off 170809
11 Cabinet Bottom Assembly 170810
12 I/O Socket 170022
13 User Port Socket 170023
14 Tape Socket 5Pin 170850
15 D.C. Socket 170024
16 DIN Socket 6Pin 170025
17 Cord D.C. 170851

/connect to A
(240V AC MAINS) CPC664 —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 RP1 Test Pack.
Please contact Amstrad PLC for information on same.

FUNCTION DIAGRAMS
ICII4 Vcc 80 BD ID 70 60 6D 50 50
mim mmmitfi itti m mENABLE
mSNAB
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S
A
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OUTPUT IaID 2D 28 3Q 3D 4D 40 GND
CONROL
ICIIS Vcc 2G IYI 2A4 IY2 2A3 IY3 2A2 IY4 2AI
\2o] m^mui]fif]ii4]m]U2]W]
nww ill lAj lAj Lil lAj lAj \l°j
IQ IAI 2Y4 IA2 2Y3 IA3 2Y2 IA4 2YI GND
10104.105 STROBE'A\DATA INPUTS
ICI09.II3 Vcc 2G SELECTVOUTPUT
,2Y
\is\w\mmm\i\\\io \^\
2C3 2C2 2CI 2C0 2Y
^
AIC3 1C2 ICI ICO IY
llJ LlJ LiJ LiJ Lil LiJ Lil LiJ
STROBE B''OUTPUT
/G SELECT DATA INPUTS IY GND
ICIIO VCC 4B 4A 4Y 3B 3A 3Y
mmmmm m rn
U\h L2J LU Lil Lil LU
IA IB IY 2A 2B 2Y GND
INPUTS OUTPUTS
Vcc ABc0' Air
w\w\mw\w\w\w\w\
j
ABCD
BCD-TO-DECIMAL
3Z5678'
i^jw^riJLTipipw
ICII2 Vcc 4B 4A 4Y 3B 3A 3Y
mloi [ei mnoi m m
Uin LU 111 lil LiJ LU
IA IB IY 2A 2B 2Y GND
ICIOS VCC BB BD ID 70 SO 6D 50 50 CLOCK
^[7<ni^i77iifin5i[Miroii<rif77i
ACLEAR] I\CLEAR\ {CLEAR
CK CK
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ULU LU LU Lil LU LU LU Lil
CLEAR IQ ID 2D 2Q 3Q 3D 4D 4Q [10]
GND
VCC 6A 6Y 5A 5Y 4A 4Y
rJ4Ui3LliplJiOoU9Lf8L,
WWW
1A 1Y ,2A 2Y 3A 3Y GND

FUNCTION FOR AMICROCOMPUTER AND IC'S
CPC664 FUNCTION DIAGRAMS
ICI07
ADRESS
BUS
I/O
PORTB
Aid
H-.4 8
E~A7
H^6
E-A4
E~A2
lh~A,
M~Ao.
2^~GND
M~RFSH )sYSTEM
^mjCONTROL
M'-RESET1~CPU
±. CONTROL
X]~~DUSRQ-~< CPU
E-wmy Bf
0NTR0L
Z^—BUSAK -I
M~g~
R}SYSTEM
|7],fiBj C0NTR0L
KEYBOAP.D SU.
ANALOG
CHANNEL CE
rEST 11
Vcc
ANALOG
CHANNEL B
ANALOG
CHANNAL A
LI
K
U
VSS K
10Al LI
10A6E
10As E
I0A4 Ee
10A3 W.
10A2 m
lOAl d
lOAo m
ICI02
CONNCTOR NO.
234
9 P P
V
DEL
T,
T
CLR
V
ESC
^
T
COPE
T
IT.
ENTE
R
7~7
TAB
W
7~
T
//7
7~
/
t:
7~
SHIf
r
CAPS
LOCK
V\
7"
7
—
ENTE
-R
SPACE
KEY „,_
-p —0/5
CTRL
RESET
C
RD C
WR C
CS C
AC
DB C
DBi C
DB2C
DB3C
DB4C
DB5C
DB6C
DB7C
DROC
DACKC
TCC
IDXC
INT
CLK
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
~^J~
UPD
765A
40 3
39
38 3
37 D
36]
35[3
34
33
32
31
30
29
28
27
26
25
24
23
22
21
vcc
3RW/SEEK
LCT/DIR
|3 FR/STP
HDL
RDY
DWP/TS
3FLT/TRc
3PS
3PSi
3WDA
3US
i3 USn
3HD
3MFM
3WE
3VCO
3RD
RDW
3WCK

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 00. 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

FLOW CHART (CONT)
3-D
Open
Repair
head connector
Write error
NG
Short
Replace
control PCB
OK
OK
Amplifier
system
Head system
Replace drive
Media failure
Adjust
positioning
Adjust
index timing
11

The data contained in the following 4pages is for information only. Service Agents must not carry
out any repair or adjustment to the Drive mechanism and its associated PCB 30001 during
warranty. Faulty mechanism must be returned to AMSTRAD for exchange.
Alignment Checks
Please use this this information in conjunction with the diagnostic flow chart.
Equipment required: Double Beam Scope; EME -CF2 Test Disk (please refer to disk notes for usage).
The following checks can be carried out in routine servicing. If the wave patterns do not appear this
confirms afault with the mechanism. Before attempting any replacement check these waveforms
thoroughly.
Content of adjustment and checking CE DISK
EMECF2
1
.
Redial adjustment by use of Track 19(Fig. 1).
2. Adjustment of the index burst by use of Track 39 (Fig. 2).
3. Azimuth check by use of Track 39 (Fig. 3-4).
O
o
o
List of Test Points
Test point Name of signal
TP 1Read signal of filter outlet
TP2 Read signal of filter outlet
TP3 Signal ground
TP5 TROO sensor output
TP9 Index signal
TP 11 Signal ground
2ms 2ms
»« •
n0.5
ms
2F IF
BLOCK 2BLOCK 3
i1
BLOCK 49
i1
IF
300us
500us -+U+-
r500us
-ii-
200ms (TOTAL 49 BLOCKS)
INDEX INDEX
Fig.l Waveform of T19 (Servo pattern)
12

ALIGNMENT CHECKS
500usec
Fig. 5-1 Index burst waveform
Amplitude
ratio (%)
uu
80
60
40
20 ^
b)
b)
10 20 30 40
Amount of Off-center (u)
Fig. 5-2 Off-centre calibration curve
(Effective width of read head is 180u)
Inner-, b/a x100%
Outer: a/bx 100%
50
Fig. 5-3 Azimuth burst
-48'
-72' +48'
°--e-s-
+72'
-B-
Fig. 5-4 shows azimuth burst in the cases of azimuth -1 2', 0' and +1 2.
T3

ALIGNMENT CHECKS (cont)
MEDIA 300us
500us
2F (125kHz
INDEX
Difference between Track 00 and 39
is within 18us (2')
Fig. 2Waveform of T39 (Index pattern -Radial alignment)
1.8ms
-500us
0.6 ms
-0.1ms
100*
INDEX I.B 123
2F(125kHz)
Fig. 3Waveform of T39 (Azimuth, alignment)
12.0 0.5 3.5 0.5 3.5 0.5
+72'-48'+48'-72'
LBLOCK 1BLOCK 2BLOCK 3
JLBLOCK 47 l
Index Aximuth burst
burst 47 pair servo-patters for positioning use
Fig. 4Waveform of T39
14

ALIGNMENT CHECKS (cont)
1) Check Positioning
1) Load CE Disk.
2) Set up track OO, Motor off.
3) Scope to TP5.
4) Adjust OO Sensor (8 on Fig. 6) so that scope shows correct difference as Fig. 2.
2) Adjustment of Index Timing
1) Load the CE Disk (refer to disk info)
2) Step the disk to the track 39.
3) Synchronise the oscilloscope by TP9 (INDEX). Set the time base to 0.1 msec/DIV.
4) Connect the probe to TP1.
Connect the ground probe to TP3 and TP1 1(ground) of PCB.
Set the input to AC and set the vertical axis to 20mV/DIV.
5) Measure timing between sweep start and an initial data pulse. It should be 500 usee ±500 usee.
When the timing is not within this range, proceed with the following adjustment. (Refer to Fig. 5-1 ).
6) Loosen the two screws fixed LED printed board. Adjust the position of LED printed board so that the
timing is 500 usee ±100 usee.
7) Re-check the timing.
8) Seek to the track 00 and make sure that the timing is within 500 usee ±200 usee. Tighten the
screws. (Fig. 5-1).
3) Check of Head Output
This check is effective only when making write and read check as described below. If the output level is
less than the prescribed output, clean the head before check.
Disk used for this check must be in good condition.
1) Load theCE Disk.
2) Select track 39.
3) Connect one of the probes of the oscilloscope to TP1 of the printed circuit board, another probe to
TP2, and the probe to ground to TP3, TP1 1(ground).
Invert one channel, and set it to Add input, set input to AC, and set the vertical axis to 50mV/DIV and the
horizontal axis to 20msec/DIV.
4) Make sure tha average output level is the following value or more: 140 mV p-p (SN 25dB or more)
If the output is less than the above-described value, replace the head.
4) Adjustment of Positioning
1) Load CE disk.
2) Select Track 19.
3) Monitor the output in the same way as the head output inspection.
Calculate the off-track amount in reference to the calibration graph, showing the interrelation
between the burst amplitude ratio and off-track amount. (Refer to Fig. 5-2).
4) The average of amplitude ratio should be below 26 urn.
If it is not within this range, make the following adjustment,
i) Loosen the bolt of the rotation stopper which fixes the screw shaft (Fig. 6-3).
Rotate the screw shaft and adjust it in such away that the amplitude ratio may become below
15 uM. Tentatively set the bolt at that position,
ii) Make the to track step to the inner and outer circles and bring it to the original position. Make sure
that the adjustment is all right. Then, tighten the bolt.
5) Confirmation of Head Azimuth
1) Load the CE Disk
2) Select Track 39.
3) Synchronise the probe of the oscilloscope by TP9 of PCB and connect another probe toTP1 ,and
the probe ground to TP3, TP1 1(ground). Set the input to AC, the vertical axis to 1mV/DIV, and the
horizontal axis to 0.5 msec/DIV. Make sure that the two outside burst waveforms are smaller than
two inside burst waveforms as shown in Fig. 5-3.
Note: Signal preceding the azimuth burst is the index burst.
If the azimuth is still incorrect reeplace the head assembly.
15

CPC664 MAIN PCB
/Reuiort
2GND
3He ort
4IN
5OUT
1R4SYNC
2G5GND
3 B «LUW
J302 PRINTER
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16 17 18

CPC664 C.P.U. CIRCUIT DIAGRAM
(+SVXOVK+SV)
SOU*) CLOCK CIWl )
(H9-CKB •USE )irniiiinuniiiuiiuiuninTnuiuiuiiuiin
1S345S78910 11 12 13 14 15 16 17 IB 19 20 21 22 29 24 25 26 27 S
A1B A13 A1
DA14 A12
I30 31 323334353637383940 41 424344484647484960
rrdois rmois lra am
HALT Mil
SEE PAGES 33/34 FOR INTERFACE CIRCUIT DIAGRAM
19

ELECTRICAL PARTS LIST
ELECTRICAL PARTS LIST CPC664
Value Circuit Reference Part No.
4ohm7
47ohm
56ohm
120ohm
150ohm
180ohm
220ohm
270ohm
560ohm
680ohm
Ikohm
1k5ohm
2k2ohm
3k3ohm
4k7ohm
10kohm
18kohm
22kohm
47kohm
470kohm
1Mohm
3M3ohm
10Mohm
4ohm7
lOOohm
R323
R156, 159
R155, 306
R1 46-1 53
R136, 218
R134
R137
R126, 128, 130
R317
R125, 127, 129, 135, 157, 158,
201-206,215,301
R113, 121-123, 132, 140, 211,
212, 216, 313,315,321
R124
R102-110, 112,214
R131
R144, 310
R1 14-1 17, 120, 133, 142,217,
309,312
R308, 31
1
R118, 119,304,305
R302, 303, 307, 319, 320
R314
R111
R101
R143, 145
R322 Fusible
R316 1/2W
170851
10020
10022
10034
10036
-1 0037
10040
10042
10050
10052
10061
10065
10069
10073
10077
10085
10091
10093
10101
10125
10147
170823
170824
170825
1422123
Ceramic Capacitors
47pF/50V
68pF/50V
220pF/50V
270pF/50V
470pF/50V
0.1uF/16V
C132
C130, 131
0133-135,310
C313
C307
C101-128, 201-213
24002
170826
400107
900400
24004
24020
Polystyrene Capacitors
0.001 uF
0.01 uF
0.047 uF
0.068uF
0.1 uF
C312
C305
C318
C302
C319
170217
170218
1409178
170219
170852
Electrolytic Capacitors
1uF/50V
22uF/10V
47uF/10V
100uF/10V
100uF/16V
C309, 311,314, 316, 317
C308
C129, 303, 306
C301,304
C315
20062
20025
1400244
20028
20028
Circ Ref. Description Part No.
210
207
IC's
IC101
IC102
IC103
IC104, 105,
109, 113
IC106
IC107
IC108
IC110,
IC111
IC112,
IC114
IC115
IC116
IC117-124
IC125
IC201
IC202
IC203
IC204
IC205
IC206, 208
IC209
IC211
IC212
IC213
IC301
IC302
HD74LS145
AY-3-8912
TMM-23256P-1952
HD74LS153
HD74LS273
M5L8255AP-5
HD6845SP
HD74LS132
Z8400APS
HD74LS32
HD74LS373
HD74LS244
HSG31 30/31 70
HM4864U-2
TC74HCU04P
UPD765AC
FDC9216BT
SN74HC240N
TMM-23128P-1951
DN74LS08
DN74LS38
DN74LS136
DN74LS27
DN74LS74
TC74HC161P
LA4140
LA63585
Transistors
Q101
Q102, 301,
Q303 302 KTC2120Y
KTC1815Y
KTC950Y
Diodes
D101
D201
D301
D302
D303, 304
IS2472-HS
DS442XFA5
IN4002
SLP-145B
KDS1555
Miscellaneous
J101
J102
J103
J104, 105
J201
J301
J302
SW301
X101
RY301
SP301
CD201
CD301
170101
40001
40022
170103
170104
170105
170106
170107
40080
40013
170108
170109
40010
170110
40008/A
40018
40020
40017
40015
40011
40019
40016
40012
40014
170813
170111
170814
170113
170114
170815
170115
170816
400111
170116
170817
Jack DIN TCS4460-01 -1011 170025
Socket DSub 9170818
HXC0730-01-010
Jack RCA 3.5 HSJ 1061 -01 -440 170022
Socket IC DILB40P-8J 1701 21
Socket IC DILB28P-8J 1701 20
Jack DC HECO470-01-630 170024
Jack DIN TCS4450-01 -101 170819
Switch Slide ESD-3975 170002
Crystal HC-49/U 170820
Relay G4S-1 112P-1-B-19 170123
Speaker CO40KO1K2451 170124
Cord Connector 170821
Cord DC 14550401 170822
No part numbers are given for any parts on PCB30001 ,should there be any electrical
fault with that PCB Service Agents should return the whole Disc Drive Mechanism
complete with the PCB for replacement.
21

GT65 CABINET EXPLODED VIEW
y>.
CAUTION! PARTS MARKED
*MUST NOT BE REMOVED
UNDER NORMAL CIRCUMSTANCES
GT65 CABINET PARTS LIST
Sym Description Part No.
1Front Cabinet 170831
2Cable Clamp 170502
3Bracket Cabinet (L) 170504
4Bracket Cabinet (R) 170503
5Bracket P.C.B. (L) 170505
6Bracket P.C.B. (R) 170506
7CRT. Green 170507
8Metal Washer CRT. 170508
9Fixing Screw CRT. 170509
10 Deflection Yoke 170510
11 CRT. Socket 170511
12 Power Tx. S/1 70832
13 Rear Cabinet 170513
14 Control Knobs 170514
15 Button Power 170515
16 On/Off Switch 170516
17 V. Hold Pot. 170833
18 Contrast Pot. 170518
19 Brightness Pot. 170519
20 D.C Cord 170316
21 DIN Cord 170317
22 D.C. Jack 170834
23 uMetal Shield 170512/SH
22

GT65 CIRCUIT DIAGRAM GT65 VOLTAGE DATA
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IC7Q1 -UPC1031H2
1-5.99V DC
2- 11.98V DC
3- 10.86V DC
4- 10.45V DC
5-0.61V DC
6-2.93V DC
7-5.26V DC
8-0V DC
9-6.0V DC
10- 11.99V DC
IC501 L78MG
1-20.1V DC
2-OV DC
3-5.5V DC
4-5.0V DC
IC502 -L78MG
1-20.7V DC
2-OV DC
3- 12.5V DC
4-4.9V DC
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23