jJT/wiSSwEEmSb
CC13
COMPUTER:
RADIO SHACK® TRS-80
MODEL
26-3002
TECHNICAL SERVICE DATA FOR YOUR COMPUTER
jftfl/ffl
RADIO SHACK TRS-80
COMPUTERFACTS
f
MODEL
PRELIMINARY SERVICE CHECKS
This data provides the user with a time-saving service tool
which
is
designed
for quick isolation
and repair of Com-
puter malfunctions.
Check
correct
interconnecting cables for good connection and
hookup before making service checks.
all
Disconnect
Computer
o
oo
W
DC
I-
peripherals except the Monitor from the
all
to eliminate possible external malfunctions.
Replacement or
repair of the
board, keyboard, or connectors
power supply board, main
may be necessary after the
malfunction has been isolated.
CM
o
o
TEST EQUIPMENT AND TOOLS
U CM
<_!
X
yj
Q
TEST EQUIPMENT
TOOLS
C/>
OO
Digital
Low Wattage Soldering Iron
Desoldering Equipment
Switch Cleaner (non spray type)
Volt/Ohm Meter
Logic Probe
<
Frequency Counter
DC
TV Monitor
Phillips Screwdriver
Small Flat Blade Screwdriver
IC Insertion and Removal Tools 14, 16, 24, and 40 pin
Alignment Tools GC Electronics: 9440
CO
O
O
REPLACEMENT PARTS AND DESCRIPTION
IDENT
CR12
CR13
F1
K1
T1
U1
U2
U3
U4
U6
U7
U8
U9
U10
PART NO.
DESCRIPTION
ADX1474
ADX1474
AHF1185
AR8130
ATA0856
AXX3051
AMX4584
Diode, 1N5401
Diode, 1N5401
Fuse,.7A
Relay
250V
Power Transformer
IC,
MC6809E
MC14050B
SCM90590P
MC6821P
SN74LS273N
MC6847P
MC6821P
MC14529B
SN74LS783N
SN74LS138N
MC1372P
MC1723CP
LM339N
MC1741CP
RAM MK4116N-3GP
IC,
SCM90522P
IC,
IC,
IC,
IC,
IC,
IC,
IC,
AMX4585
@
IC,
IC,
U11
IC,
U12
U13
U14
U15
U20
IC,
IC,
IC,
IC,
thru
U27
U28
Howard W. Sams & Co*, Inc.
4300 West 62nd Street, P.O. Box 7092, Indianapolis, Indiana 46206 U.S.A.
&M*£Ww9r*
The
listing of
any available replacement part herein does not
Reproduction or use, without express permission, of editorial or pictorial
No
constitute in any case a recommendation, warranty or guaranty by
content, in any manner,
Howard W. Sams £ Co.
respect to the use of the information contained herein.
replacement
part.
,
Inc.
as to the quality and suitability of such
The numbers
from information furnished
manufacturers
,
to
of these parts
have been compiled
Howard W. Sams 8
of the particular
Co., Inc., by the
type of replacement part
listed.
©
1986 Howard W.
is
prohibited.
Sams &
patent
assumed with
liability is
Co., Inc.
4300 West 62nd Street, P.O. Box 7092, Indianapolis, Indiana 46206 U.S.A.
Printed in U.S. of America.
85CC14951
DATE
1-86
26-3002
PRELIMINARY SERVICE CHECtCS
(Continued)
TV
MONITOR
CASSETTE
POHER
L£Fr
JOYSTICK
RESET
RJgHT
JOYSTICK
-Q-
@
155
CHANNEL 2
RF
MODULATOR
SOW
s
SI
PULSES
POUER SUPPLY
BOARD
©@
012
©
CPU
03
U28
0!
VIDEO MIXER
35
84
(3>
i
PULSES
"
PI
07
VD6
SI
i
30
i
®
ROM
EXPANSION
ROM
.MI2L
CARTRI06E
PORT
a|
PULSES
(3D)
us
]
O®™ ®
-\
©
4 2 IS
PIA
U4
P!A
UB
®
®
(2A)
3.57S»fz
i
wo
PULSES
4
t2
.
©
©
S
4C
10
U2
clock
C4
BUFFER
©
U16
DYNAMIC
RAM
CONTROLLER
PULSES
19
®
TP12
5.0V
U2?
RAH
U11
P6
fiFP
decoder
U24
RAM
U25
RAW
023
SAB
U20
SAM
U22
RAM
U21
RAM
\
PULSES
n..
02S
RAH
UC)
©@
© ©
KEYBOARD
RADIO SHACK TRS-80
INTERCONNECTING DIAGRAM
SI
INTERCONNECTING DIAGRAM
MODEL
26-3002
PRELIMINARY SERVICE CHECKS
(Continued)
U12(4B)(4D)
U10
CLOCK
©
@@©
U9
g
P1N14
PULSES
PIN 9
VOLTAGE
® ®
IAIN
V!
BOARD
U13
880
3D
adjust
PIN 39
PIN 19
TP12
w^Ji^^/p
(8A
U11
?%
f6A)
(6C)(6E
U2?
U28
U25
U24
U23
U20
U22
U21
PIN 11
PULSES
© @ @@
MAIN BOARD
PRELIMINARY SERVICE CHECKS
(Continued)
SERVICE CHECKS
'MATCH THE NUMBERS ON THE INTERCONNECTING DIAGRAM AND PHOTOS WITH
THE NUMBERS ON THE SERVICE CHECKS TO BE PERFORMED.
©
COMPUTER DEAD
(C)
Colors are not correct. Check for a frequency of
at pin 7 of IC U10. If the frequency is
not correct, check the adjustment of the Clock
3.579MHz
(A)
Check
for
18VAC
at
connectors E1 and E2 and
11.0V at connector E3.
If
Trimmer
the voltages are miss-
(C4) (See "Miscellaneous Adjustments") and check IC U10 by substitution.
check Fuse F1. If Fuse is good check the
windings of Transformer T1 for continuity.
ing
(D)
(B)
missing at pin 3 of connector E, check
the 19VAC winding of Transformer T1 for continuity and check Diodes CR12 and CR13.
If 1 1
.0V
is
(C)
If the voltages are correct at connectors E1, E2
and E3, check for 5.0V at TP12. If 5.0V is missing
check the Error Amp IC (U13) by substitution.
(D)
not correct at TP12, check the
adjustment of the 5V Adjust Control (R60) (see
"Miscellaneous Adjustments").
(s)
If the frequency is correct at pin 7 of IC U10,
check IC U12 by substitution.
SOUND
(A)
No sound. Type
program:
10
(T)
If
the voltage
(B)
Computer
(CPU)
justments").
dead. Check for pulses at pins 34
and 35 of the CPU IC (U1). If pulses are missing,
check the Dynamic RAM Controller IC (U10) by
pulses are not present at pin 3 of the RF
Modulator, check for pulses at pin 14 of the
Analog Multiplexer IC (U9). If pulses are present,
substitution.
check IC U9 by substitution.
is
(B)
pulses are present at pins 34 and 35 of IC U1,
for pulses on pins 24 thru 31 of IC U1 while
turning the Computer On. If no pulses appear
check IC U1 by substitution.
(C)
If
If pulses appear on pins 24 thru 31 of IC U1, then
suddenly stop, check RAM IC's (U20 thru U27),
ROM IC (U3) and Expansion ROM IC (U28) by
pulses are not present at pin 14 of IC U9, check
PIA IC (U4). If
pulses are present, check the Buffer IC (U2) by
substitution. If pulses are missing check IC U4
by substitution.
If
for pulses at pins 4 thru 9 of the
©
KEYBOARD
(A)
Keyboard
dead. Check the Keyboard Connecgood connections.
is
VIDEO
(B)
No
video.
Check the VDG
IC (U7)
and Video Mix-
(B)
If
IC's
ment
U7 and U12 check good, check the adjust-
(C)
Video Level Control (R21) (see Miscellaneous Adjustments).
Dots
from the alphanumeric
characters. Check IC U7 by substitution.
(D)
Wrong characters appear on the Monitor
Check IC's U6 and U7 by substitution.
are
(A)
No
Check for a frequency of 3.579MHz at
Dynamic RAM Controller IC (U10). If
the 3.579MHz signal is missing, check IC U10 by
color.
substitution.
(B)
the 3.579MHz signal is good, check the Video
Mixer IC (U12) by substitution.
If
pulses are present at pin 11 of IC U11, check
(D)
One key
(E)
A group
(F)
More than one letter appears on the Monitor
screen when a key is pressed. Check for shorted
keys or keys that are stuck down.
screen.
pin 7 of the
If
the PIA IC (U8) by substitution.
missing
COLOR
the Keyboard Connector (P6) checks good,
for pulses at pin 11 of ICU11. If pulses are
missing, check IC U11 by substitution.
of the
(C)
If
check
er IC (U12) by substitution.
IV
If
tor (P6) for
(A)
©
10
for pulses at pin 3 of the RF Modulator. If
pulses are present, check the adjustment of the
Sound Coil (L4) (See "Miscellaneous Ad-
OPERATION
substitution.
©
GOTO
Check
check
(C)
200,200:
and run the following Basic
is
MICROPROCESSOR
(A)
SOUND
in
is erratic. Clean the contacts of the bad
key and recheck the operation of the key.
of keys do not work. Check the Keyboard Connector (P6) for good connections and
check IC U8 by substitution.
PRELIMINARY SERVICE CHECKS (Continued)
SERVICE CHECKS (Continued)
©
CASSETTE
(B)
(A)
(B)
Cassette motor will not run or runs all the time.
Check Relay K1 contacts from pin 1 to pin 3 of
connector P5. Check for continuity while saving
or loading a program from tape if the cassette
motor
will
stuck)
if
If
not run.
Check
substitution.
(C)
a short (contacts
the cassette motor runs all the time.
for
(C)
(D)
If pulses are present at pin 11 of IC
U11, check
for pulses at pins 4 thru 9 of the PIA IC (U4). If
pulses are missing, check IC U4 by substitution.
Relay K1 checks good, check the PIA IC (U4) by
(D)
substitution.
pulses are present at IC U4, check for pulses at
If pulses are missing, check IC
U2 by substitution.
If
pin 15 of IC U2,
Programs can not be saved to tape. Check the
PIA IC (U4) and Buffer IC (U2) by substitution.
Programs can not be loaded from
U4 and U14 by substitution.
tape.
(E)
Check
IC's
®
pulses are present at pins 19 and 39 of IC U8,
for pulses at pin 11 of the Decoder IC
(U11).
If pulses are missing, check IC U11
by
If
check
JOYSTICKS
(F)
If pulses are present at IC U2, check
for a varying
voltage at pi 9 of the Analog Multiplexer IC (U9)
while operating the joystick. If the voltage does
not vary, check IC U9 by substitution.
If
the voltage varies at pin 9 of IC U9, check IC
substitution.
U14 by
(A)
Joystick does not work.
following program:
Type
in
and run the
(G)
Joystick
joystick
10
do not work.
Check the
switches for continuity and
check the joystick Connectors (P3 and P4) for
good connections.
FORX = 0TO3
20Y = JOYSTK(X)
30 NEXT X: GOTO
buttons
button
3J
10
(H)
While the program is running check for pulses at
pins 19 and 39 of the PIA IC (U8). If pulses are
missing, check IC U8 by substitution.
the joystick buttons and connectors check
good, check PIA IC (U8) by substitution.
If
SERIAL
(A)
I/O
PORT
does not work. Check the PIA IC
U14 and U15 by substitution.
Serial port
and
IC's
(U4)
—>
a
q5
O CO
m
X
r>
io o
9 •x
g -I
o
30
to CO
MISCELLANEOUS ADJUSTMENTS
RF MODULATOR
5V ADJUST
Connect the input
of a voltmeter to TP12. Adjust the
just Control (R60) for a voltage of 5.0V at
5V Ad-
TP12.
Connect the Computer to a TV Monitor and set the TV and
Channel Select Switch (S3) to the same channel (channel 3
or 4). Type in and run the following Basic program:
CLOCK ADJUST
10
Connect the input of a frequency counter to pin 13 of the
Dynamic RAM Controller IC (U10). Adjust the Clock Trimmer (C4) for a frequency of 894.886kHz.
SOUND
200,2:
GOTO
10
Adjust the Channel Coil (L5) for best picture and sound and
Sound Coil (L4) for best sound with minimum
adjust the
noise.
00
O
PRELIMINARY SERVICE CHECKS
(Continued)
U12(4B)(4D)
U10
CLOCK
©
@@©
U9
g
P1N14
PULSES
PIN 9
VOLTAGE
® ®
IAIN
V!
BOARD
U13
880
3D
adjust
PIN 39
PIN 19
TP12
w^Ji^^/p
(8A
U11
?%
f6A)
(6C)(6E
U2?
U28
U25
U24
U23
U20
U22
U21
PIN 11
PULSES
© @ @@
MAIN BOARD
PRELIMINARY SERVICE CHECKS
#«***
*,
^r
-
,
(Continued)
z
%:
**;•>.&&
©
v_y
F1
.
~T1
.7A
-cri3
-CR12
POWER SUPPLY BOARD
VII
fie;
PRELIMINARY SERVICE CHECKS
(Continued)
PREVENTATIVE MAINTENANCE
ENVIRONMENT
Computers perform best in a clean, cool area that is below 80 degrees Fahrenheit and free of dust and smoke particles. Even
though home Computers are not affected by cigarette smoke as much as commercial Computers are affected, it is better
to
maintain a smoke-free area around the Computer.
Monitor, Printer, or other power devices.
Do
not block cabinet vents of any of the
Computer system; Computer,
ELECTRICAL POWER
Variations
the line voltage can affect the Computer. Try to avoid these fluctuations by using an AC receptacle that is on
a
used by appliances or other heavy current demand devices. A power-surge protector, power-line conditioner, or
non-interruptable power supply may be needed to cure the problem. Do not switch power On and Off frequently.
power
in
line not
KEYBOARD
Liquids spilled into the Keyboard can ruin
it.
Immediately after a spill occurs, disconnect the Computer power plug from AC
Then, if circuitry or contacts are contaminated, disassemble the Keyboard and carefully rinse the Keyboard
printed circuit board with distilled water and let it dry. Use a cotton swab to clean between the keys. Use a non-abrasive
contact cleaner and lint-free wipers on accessible connectors and contacts.
power
outlet.
DISK DRIVES
Clean the read/write heads of the Disk Drives about once a month or after 100 hours usage. Use only an approved head cleaning
kit.
Handle carefully to preserve proper disk head alignment. A sudden bump or jolt to the Disk Drives can knock the disk head out
If the disk drive must be transported, place an old disk in
slot and close door during transport.
of alignment.
Store disks
in
on the back
their protective covers
and never touch the disk surface. Observe the disk handling precautions usually found
of disk protective covers.
PRINTERS
Carefully
The
vacuum
oil will
the Printer regularly.
collect abrasive grit
Wipe surface areas clean using a
and dust. The dust
will
Do not oil the machine.
components to overheat and fail.
light all-purpose cleaner.
act as a blanket. This can cause
STATIC ELECTRICITY
Static electricity discharge can affect the Computer. In order to minimize the possibility, use anti-static mats, sprays,
tools
and materials, and maintain good humidity in the Computer environment.
MONITOR
Use an isolation transformer with any Monitor that does not come as part of the system since some Monitors use a HOT
chassis (chassis connected to one side of the AC line). The face of the Monitor should never be left on for long periods of time
at high brightness level except when pattern is being changed periodically. Use caution when cleaning
anti-glare screens, to
preserve the glare-reduction feature.
VIII
5j"/M f
RADIO SHACK TRS-80
COMPUTERFACTS"
o
MODEL
26-3002
'i-**
oo
DC o
HO
O CM
< _|
X nj
WQ
OO
Q*
<
U?Ut*f>'-'''#'*<:~-*\
I
'
"
I
I
o
o
CC
CO
T™
3J
o
o
>
O
o
X
>
o
(fl
PRELIMINARY SERVICE CHECKS
ro
O)
SAFETY PRECAUTIONS
ENCLOSED
See page
w
o
M
18.
INDEX
o
Page
Block Diagram
Disassembly Instructions
General Operating Instructions
GridTrace Location Guide
IC Pinouts and Terminal Guides
5
Safety Precautions
17
15,16
Miscellaneous Adjustments
20
18
2,23,24,25
17
8
Troubleshooting
7
Parts List
3,4,21,22
Schematics
Schematic Notes
Test Equipment
19
Logic Chart
8,9,10
11 thru 14
SAMS*
listing of
7
Photos
Main Board
Power Supply Board
7
Line Definitions
The
Page
6
Howard W. Sams & Co., inc.
4300 West 62nd Street, P.O. Box 7092, Indianapolis, Indiana 46206 U.S.A.
any available replacement part herein does not
constitute in any case
Howard W. Sams &
a recommendation, warranty or guaranty by
Co., Inc., as to the quality
and
suitability of
such
Reproduction or use, without express permission, of editorial or pictorial
content, in any manner,
is
prohibited.
No
patent
liability is
assumed with
respect to the use of the information contained herein.
replacement part. The numbers of these parts have been compiled
©
from information furnished to Howard W. Sams S Co.,
4300 West 62nd Street, P.O. Box 7092, Indianapolis, Indiana 46206 U.S.A.
Inc.,
manufacturers of the particular type of replacement part
by the
listed.
1986 Howard W.
CO
oo
Sams &
Printed in U.S. of America.
Co., Inc.
85CC1 4951
DATE
1
-86
P/J6A
NC >
3
P/J6
-«-,
PART.0F.R75
3-4-
J IPIPIPIPIPIPIPI T^g
HC6821P
DO-
eue
33
7
R/W
PIA
I
7
P!
20
21
PI
l
D2
P/JB
PI
-»-
s
-5ND
e
U3
e U10
PI
P1
24
ROM
DYNAMIC
cm
RAM
—
><
CONTROLLER
»—
—v\*
'
-J-
—f-
_
L
2 P
,_n
-MA2
25
._i
S30
-MA3
7
•A0-
S31
27
PI
JT Pi
26
PARTJFJ75
53
PI
2S
P/J6
P/.
33
r +7—— a+
22
30
PI
13
40
-MA5
MA2
1
19
P1
SI
-MA4
"J
28
PI
•
SCS
12
•
-SLENB-
^
FT Pi FT Pi
P1
P/J6
P/JBA
-»-
S2B
-MA6
PART_0F.R77
21
PI
38
545
547
S46
7
10
P/JB
P/JBA
37
RAS
PI
12
550
ENTER
CLEAR
551
BREAK
CLOCK
®C4
J
P1
15
IS
P1
r
9pF-35pF
"i
c^z
5.0V GO
U25
U26
U27
RAH
RAM
RAM
RAM
RAM
RAN
14 P
12
m
D7-
10
-s.ov
1
1
20
19
A
<[t]
S.OVCM
S.OV (ED
14 P
14 P
14
4
MD2
MD1
UL
MAS
HALT-
C40
T
20
I
R75
I
R1
100K"
J6
I6/32Kr-i
UA
76
r
i4K
I
<-
e
U24
•DS-
MD7
P
MD3
M04
MD5
MD6
MD7
PART Of £75
33
33
1N4148*
'4PPI
e
U23
15
MA4
32
A
VDG CLK-
3
34
RAM
e
U22
MD6
.2|iS
PI
•
RAM
S
05-
14IP
SN74LS02N
PART 0FU29
CR2ir
S.OVCM
°U21
•D4-
MD5
33
^
—'.4V39pFT
17
I
13
U20
1
e
MD4
C51_
3.3V
•NC
8
T T
S
e
D3-
14 P
14 31818MHz
P/JB
P/JBA
|
MK4116N36P MK4116N3GP MK4116N36P MK4116N3GP MK4116N36P KK4116N3GP MK4116N3GP SCM90072P
PARTJF.R75
XI
J
EN1
13
PI
_^.
20 P
20 P
PI
14
16
10
SN74LS244N
e..
16
14 P
39
11
7
12
11
D1
14 P
PI
PI
2 P
7
23
39
EN2
S49
CAS
MAS
31
CTS
P/J6
2 P
P
3
WE
33
P/J
2 P
6
>t
I
HD1
MD3
2 P
5
MA!
DO-
MD2
2 P
i
MDO
D7
D6
2 P
PART_0FJi76
P
29
CART
,_rT
D5
D4
2|P
22
23
03
5N74LS783N
5CH90590P
RESET
P/JBA
MAO
I
1
4
I
'
J
{
__
R75
LOW
HIGHo
PHOTO CIRCUITRACE =
Q|
SCHEMATIC CIRCUITRACE =
[TTI
13
12
I
I
J-*^^-*-*- mab
'
a
4i
.
—U-vvv1,«
Z.
RESET
1
PART OF
R75
33
J7
1
15
p/.
'#5-
«r
©LM339N
-OTTL
13
PA
P22-
<<r
12
——
<
i
C57
T5
.0022
10X
n
T
C54_
.022T
.022T
11
10
OV
4
2.5V
2.8V
r
OV 2.BV 5.0V
3
2
1
8
14
OV
sr
38
I
:
t
4-CASS MOT
T
CASSETTEENABLE
m
R30
5.0V 00
m
5.0V CM
WBl
.022J
ssr
CR7ip
1N4148*
e
S.OVCM
S.OVCM
SEE PACES 17 AND 19
wv-
R34
8200
K1
DAO-
m
100
1
220
RAS
R/W-
.022T
R50
MPS2222A
04 RELAY DRIVE
R71
1.0V
^>W
.«»
11
IN414I
11.9V
13
R40
©
SN74LS02N
PART 0FU29e
JS>
C5B1
^
.0022X
16
CR9/
S.OV CM
1N982AV
± e
.022'
SN74LS02N
PART OFU29
....
CR10/
1N982AV
•NC
P P
10 4
14
PIAO
m
'I
C80
SN74LS138N
1000
m
FOR TERMINAL GUIDES AND NOTES
OV
n,
4.BV
IB
C7S1
SEL
3>
LM339N
PART 0FU14
1000
12
-«-
PART 0FMC14529B
U9
OV
6
'S3
PART OFU14
ANALOG MULTIPLEXER
L3
•NC
10/iFf
S.OV CM
"*4
R32;
4700-
5.0V CM
CABLING
HEAVY LINES REDUCE
USE OF MULTIPLE LINES
24
CASS OUT
CR18j;
1N4148*
R7;
4700i
R31
4700
SLENB
CTS
SCS
CASS OUT
CSN
m
CASSDIN
S.OVCM
A PHOTOFACT STANDARD NOTATION SCHEMATIC
WITH
MAIN BOARD
2
©
HmnnzEi
Howard W. Sams & Co.,
Inc.
1986
RADIO SHACK TRS-80
MAIN BOARD
MODEL
26-3002
02
C
E
8
U9
U15
U14
Q4
U8
U4
Q1
U6
U12
U7
U28
U2
U3
U16
U1
U10
o
o
CO
oo
?!
ro
U18
U19
5.0V(A)
-12,0V
ARROWS ON
MAIN BOARD
22
* HowaMl "• Ssm *
IC'S INDICATE PIN
HE33HZ51 p,™ te
1
•5.0V
5.0V{B)
11JV
UNLESS NOTED
MAIN BOARD
3
*
.
|
10
12
11
I
13
14
^
15
|
17
16
18
2!
IS
22
I
23
24
25
27
2S
28
I
!
,
:
'"""""""
B
I
ml
?K
W
Wr
C
j;
I
«
r
E
,:.>:
F
J?
•
jKir
*
•
u*
,.
:
E
F
I
"iraffai
:l
G
:
£
H
j
14
•ni
1
s2
oo
Pi
*2
H
,'"^yi^.*t;&g,»i
I
r
7
J
T~
.
r
J
'-#!;*£
K
K
•
'.
-a-
'J=
*
L
•i M
N
,£.
'
N
1
till
r
,
p
Q
2
MAIN BOARD
4
j
3
j
4
|
5
j
A Howard W. Sams icianil:fj«am
8
[
8
7
I
Phnto
9
I
|
10
|
11
|
12
|
13
|
14
|
15
|
16
|
17
|
18
|
19
|
20
|
21
|
22
|
23
|
24
|
25
?6
27
28
MAIN BOARD
21
GridTrace
LOCATION GUIDE
C1
C-24
C2
C3
C4
C5
C6
C7
C8
C9
C10
H-11
J-21
L-21
F-21
L-1
M-13
C11
N-11
CI 2
C-13
E-24
CI 3
C14
C15
C16
C17
C18
CI 9
C23
C24
C25
C26
C27
C28
C29
C30
C31
C32
C33
C34
C35
C36
C37
C38
C39
C40
C41
C42
C43
C44
C45
C46
C47
C48
C49
C50
C51
C52
C53
C54
C55
C56
C57
C58
C59
C60
C61
C62
C63
C64
C65
C66
C67
C68
C69
C70
C71
C72
C73
C74
C75
C76
C77
F-15
0-2
P-28
P-11
M-6
M-10
L-2
M-1
P-9
N-23
1-13
H-13
F-15
0-16
C78
C79
C80
E-8
F-8
B-10
D-12
F-24
E-15
R24
R25
R26
R27
R28
R29
R30
1-23
R31
CR1
C-24
CR2
CR3
CR4
CR5
CR6
CR7
CR8
CR9
CR10
K-21
R32
R33
R34
R35
R36
R37
R38
R39
R40
C81
C82
C83
C84
C85
C-11
D-24
H-11
C-10
D-10
D-11
E-17
F-11
F-11
CR11
1-1
CR14
CR15
CR16
CR17
CR18
0-8
N-2
1-13
N-9
G-11
M-1
El
F-1
N-17
E-18
0-18
0-18
N-20
H-20
E2
E3
E4
E8
G-1
0-21
J3
L-7
P-15
N-15
P-16
0-9
L-6
N-2
J4
J5
J6
J7
K-17
K-23
L-5
K1
D-11
L2
E-13
E-13
D-17
B-19
G-26
B-9
B-7
B-4
0-21
C-24
E-15
F-15
G-13
J-23
0-24
C-24
N-25
0-26
0-26
E-22
L-20
H-9
J1
J2
L3
L4
L5
PI
P2
P3
P4
P5
P6
01
M-21
C-3
02
03
04
C-3
R1
C-5
B-5
R2
R3
R4
C-8
E-23
1-16
P-17
0-17
N-19
0-19
0-20
N-21
0-22
0-22
N-24
0-25
0-25
N-27
K-22
N-15
M-24
D-25
D-24
R5
R6
R7
R8
R9
RIO
R11
R12
R13
R14
R15
R16
R17
R18
R19
R20
H-1
J-1
L-1 7
B-11
0-14
D-14
K-9
L-11
E-11
D-24
D-24
E-24
E-23
1-20
E-16
1-20
C-13
D-14
K-20
K-20
K-20
K-20
K-20
K-21
E-13
L-21
R41
R42
R43
R44
R45
R46
R47
R48
R49
R50
R51
R52
R53
R54
R55
R56
R57
R58
R59
R60
R61
R62
R63
R64
R65
R66
R67
R68
R69
R71
R72
R73
R74
R75
R76
R77
R78
R79
R80
R82
R83
SI
S2
S3
TP12
U1
U2
U3
U4
U5
U6
U7
U8
U9
E-8
G-10
H-10
C-10
D-10
D-10
1-10
G-11
G-11
H-11
H-11
1-11
1-11
E-10
E-10
E-10
D-10
G-11
G-11
K-21
E-18
D-22
C-23
C-13
H-10
1-10
C-8
G-10
H-10
G-10
H-10
G-10
H-10
L-20
0-9
M-9
P-12
0-12
0-12
N-11
N-10
N-10
M-1
N-1
H-20
H-13
E-12
1-20
L-2 2
M-23
L-2 3
M-26
M-26
N-26
N-27
1-18
D-22
J-23
C-23
C-2
B-13
0-15
G-23
K-19
F-20
L-1 7
C-18
H-1 7
R21
E-15
E-15
E-17
C-14
U10
R22
R23
1-13
U11
H-8
L-22
0-16
E-8
U12
F-1
G-16
L-1
U13
U14
U15
U16
U17
U18
U19
U20
U21
N-9
F-10
D-8
L-19
0-7
N-3
N-1
0-24
0-27
0-26
0-23
0-22
0-20
0-19
0-18
U22
U23
U24
U25
U26
U27
U28
U29
M-14
X1
M-21
F-1
o
o
30
>
OO
D
m
rO)
W
O
O
3J
o
-I
KEYBOARD
WIT
i-
J_JL
cmwi
mom
PR0CESSIN8
awre
WIT
JOYSTICK
PORTS
control
PfWCESSINS
TO PROVIDE POWER FOR ALL ACTIVE COHPONENTS
,
BLOCK DIAGRAM
6
,
POWER
SYSTEM
SOPPLY
TWINS
TO ALL CL0CKIN6 FUNCTIONS
DISASSEMBLY iNSTRUCTIONS
CABINET REMOVAL
Remove seven
Computer
MAIN BOARD REMOVAL
screws from cabinet bottom, turn
up and lift cabinet top off.
phiilips
right side
Remove Power Supply Board and Keyboard. Remove
phiilips
ten
screws holding Main Board and remove from
cabinet.
POWER SUPPLY BOARD REMOVAL
KEYBOARD REMOVAL AND DISASSEMBLY
Remove
three phiilips screws holding power supply board.
Unplug power supply connectors and remove power supply
board.
Unplug keyboard from Main Board and remove keyboard
from cabinet. Turn the keyboard upside down and remove
21 phiilips screws from the bottom. CAREFULLY lift bottom cover off the keyboard (the keys and contacts are held
in place by the bottom cover and will fall out if the keyboard
is not laying face down.
GENERAL OPERATING INSTRUCTIONS
POWER UP
CASSETTE OPERATION
The Computer will come up in Basic mode when turned On
with no cartridge in the cartridge slot. If a cartridge is installed, the Computer will come up running the program in
Connect a Cassette Recorder to the Cassette Socket (P5)
on the Computer. The black plug on the cable connects to
the Earphone jack, the large gray plug connects to the Auxiliary jack and the small gray plug connects to the Remote
On/Off jack on the Recorder. To load a program, type
the cartridge.
RESET
CLOAD, press the Return key, then put the Recorder in Play
mode with the volume turned about halfway up. An S will
The Computer can be Reset by pressing the Reset Button
(S1) located
BASIC
on the
right rear of the cabinet.
PROGRAMS
A program in Basic can be started by typing RUN and
ing the ENTER key. The program can be stopped by
ing the
BREAK
presspress-
key or the Reset button.
appear on the Monitor screen while the Computer searches
for the program. When the Computer finds the program the
letter F will appear on the Monitor screen, then the word OK
will appear after the program has been loaded.
To Save a program to tape, put the Recorder in Record
mode, type CSAVE and press the Return key. The word OK
will
appear on the Monitor screen after the program
is
Saved.
MISCELLANEOUS ADJUSTMENTS
5V ADJUST
Connect the input
VIDEO LEVEL
of a voltmeter to TP12. Adjust the
just Control (R60) for a voltage of 5.0V at
5V Ad-
TP12.
CLOCK ADJUST
Connect the input
of a scope to the emitter of the Video
Transistor (Q1).
Set the scope sweep to 20/tSec,
voltage range to 1V, DC input and trigger to negative slope.
Adjust the Video Level Control (R21) for a blanking level of
Amp
2.35V (See Figure
1).
Connect the input of a frequency counter to pin 13 of the
Dynamic RAM Controller IC (U10). Adjust the Clock Trimmer (C4) for a frequency of 894.886kHz.
RF MODULATOR
Connect the Computer to a TV Monitor and set the TV and
Channel Select Switch (S3) to the same channel (channel 3
or 4). Type in and run the following Basic program:
10
SOUND
200,2:
GOTO
10
Adjust the Channel Coii (L5) for best picture and sound and
adjust the Sound Coil (L4) for best sound with minimum
noise.
2.35V
Figure
1
o
o
05
TEST EQUIPMENT
SAMS' Engineers
Test Equipment listed by Manufacturer illustrates typical or equivalent equipment used by
measurements and is compatible with most types used by field service technicians.
to obtain
TEST EQUIPMENT (COMPUTERFACTS)
8 & K Precision
Equipment No.
Equipment Name
OSCILLOSCOPE
LOGIC PROBE
LOGIC PULSER
1570A,1590A,1596
Simpson
Equipment No.
Sencore
Equipment No.
SC61
454
DVM37,DVM56,SC61
463,467,470,474,467E
DP51
DP101
VOM
ANALOG VOM
DIGITAL
2830
277
260-7,160,165,
260-6XL.260-7P,
260-6XLP
ISOLATION TRANSFORMER
FREQUENCY COUNTER
COLOR BAR GENERATOR
RGB GENERATOR
FUNCTION GENERATOR
HI-VOLTAGE PROBE
VOM/DMM
TR110,1604,1653,1655
PR57
1803,1805
FC71.SC61
710
1211A,1248,1251,1260
CG25.VA62
431
1260
420A.420D
3020
HP200
HV-44
248
00168,00411,00749
Accessory probes
TEMPERATURE PROBE
TP-28
I
R-1 0,00760,00758;
383,389,388
CRT ANALYZER
CR70
467,470
TROUBLESHOOTING
-
COMPUTER DEAD
12.1V
is
present
3 of IC U19.
Remove
all
peripheral equipment that
is
connected to Com-
puter except the Monitor. Turn Computer On. Check the
operation of Computer. If Computer works properly, turn
Computer Off, plug peripherals in one at a time and recheck
operation of Computer until peripheral causing the problem
is found. If Computer does not work with peripherals disconnected, check for 5.0V at TP1 2, - 5.0V at TP1 1 and 1 1 .9V
3 of Voltage Regulator IC (U17). If voltages are missing, refer to "Power Supply" section. If voltages are correct, check for pulses on Data pins (24 thru 31) and Address
pins (8 thru 23) of CPU IC (U1). If pulses are missing at any
of the pins, refer to "Microprocessor Operation" section. If
pulses are present, refer to "Video" section.
at pin
POWER SUPPLY
Computer
is
Dead. Check Fuse
for possible shorts to
ground
(F1).
If
Fuse
is
bad, check
Voltage Regulator IC's
(U17, U18 and U19), Regulator Transistor (Q2) and check for
possible shorted primary or secondary windings on
at
Transformer T1. If Fuse F1 is good, apply 120V AC power
and check for 36V AC from pin 1 to pin 2 and 11.0V.from pin
3 to ground of connector E. If all voltages are missing,
check for open windings on Transformer T1. If 36V AC is
present from pin 1 to pin 2 and 11.0V is missing at pin 3 of
Connector E, check 19V AC winding of Transformer T1 for
possible open circuit and check Diodes CR12 and CR13. If
voltages are correct at Connector E, check for 5.2V at Collector of Regulator Transistor (Q2). If 5.2V is missing, check
voltages and components associated with pins 2 thru 6 and
10 thru 13 of Error Amp IC (U13) and Regulator Transistors
(Q2 and Q3). If voltage reading is not correct at Collector of
Q2, check adjustment of 5V Adjust Control (R60), see
"Miscellaneous Adjustments". If voltage is correct at Collector of Transistor Q2, check for - 12.1 V at pin 3 of Voltage
Regulator IC (U18). If -12.1V is missing check Diodes
CR11 and CR15, Electrolytics C9 and C17 and IC U18. If
trolytic
If
at pin
-5.0V
C18 and
is
IC U19.
3 of IC U18, check for -5.0V at pin
missing, check Resistor R67, ElecIf
-5.0V
is
present at pin 3 of IC
U19, check for 11.9V at pin 3 of IC U17.
If
11.9V
is
missing,
check Diodes CR11 and CR14, Electrolytic C7 and IC U17.
MICROPROCESSOR
(CPU)
OPERATION
Computer is dead, power supply checks good. Use a scope
to check data lines (pins 24 thru 31 of IC U1) for activity. If
there is no activity check operation of reset circuit by
checking logic reading at pin 37 of CPU IC (U1). The reading
should be Low when the Computer is turned On then immediately go High. The logic reading should also be Low
whenever Reset switch (S1) is pressed. If logic reading is
not correct at pin 37 of IC U1 when Computer is turned On,
check Electrolytic C1, Diodes CR1, CR2 and CR3 and
Resistor R2. If Power On reset works but Reset Switch (S1)
does not work, check Switch (S1), Capacitor C40, Diodes
CR1 and CR3 and Resistor R1. If reset circuit is operating
properly, check for 894.886kHz clock pulses at pins 34 and
35 of IC U1. If clock pulses are missing, check waveform at
pin 5 of the Dynamic Ram Controller IC (U10). If waveform is
missing, check Crystal X1, Capacitor C51, Trimmer C4,
Resistor R43 and IC U10. If waveform is present at pin 5 of
IC U10, check waveforms at pins 13 and 14 of IC U10. If
waveforms are missing at pins 13 and 14 of IC U10, check IC
U10 and Capacitors C73 and C75.
If
clock pulses check good at pins 34 and 35 of IC U1 check
,
a logic High at pins 2, 3, 4 and 40 of IC U1. If logic
reading is not correct at any pin, check IC's and comfor
ponents that are connected to defective
pin.
for address lines that may be stuck logic High or
Low, connect a Jumper from pin 40 of IC U1 to ground. All
address lines (pins 8 thru 23 of IC U1) should check logic
open. If any address line checks logic Low or High, check
To check
IC's that are
connected to defective line. Grounding pin 40
causes pins 24, 25, 27 and 28 of IC U1 to go
of IC U1 also
TROUBLESHOOTING
Low and pins 26, 29, 30 and 31 to go logic High. If any
readings are not correct on pins 24 thru 31 of IC U1, check
logic
IC's
connected to pin with incorrect reading.
will come up properly when turned On, if PIA IC
Analog Multiplexer IC (U9), IC U14 and Expansion ROM
IC (U28) are removed. Turn Computer Off and reinstall IC's
one at a time and recheck opertion of Computer until defec-
(Continued)
Colors
Check for a frequency of
Dynmaic RAM Controller IC (U10). If
frequency is not correct, check adjustment of the
14.31818MHz Clock Trimmer (C4), see "Miscellaneous Adare
3.57954MHz
Computer
justments".
(U8),
justing
tive IC is located.
If
pulses appear on data pins (24 thru 31) of IC U1 when
is turned On then suddenly stop, check RAM IC's
Computer
(U20 thru U27),
ROM
IC (U3) and Expansion
ROM
not
correct.
at pin 7 of
If
correct frequency cannot be obtained by ad-
Trimmer C4, check Crystal X1, Capacitor C51,
Resistor R43 and IC U10. If frequency is correct at pin 7 of
IC U10, check waveforms at pins 5 and 7 of Video Mixer IC
(U12). If waveforms are missing or incorrect, check VDG IC
(U7). If waveforms are present, check IC U12.
SOUND
IC (U28).
No sound. Type
in and run following Basic program. The
program produces a continuous tone from Monitor speaker.
VIDEO
No
video.
sistor (Q1).
Check waveform at emitter of Video Amp TranIf waveform is present check adjustment of
Video Level Control (R21) and check for 6.1V at pin 2 of RF
Modulator. If Control R21 is adjusted properly and 6.1V is
present at pin 2 of RF Modulator, check RF Modulator. If
6.1V is missing at pin 2 of RF Modulator, check Resistor
R45. If R45 is good refer to the "Power Supply" section of
this Troubleshooting guide.
If waveform
waveform at
Q1, check
waveform is
present at pin 12 of IC U12, check voltages and components
associated with Transistor Q1. If waveform is missing at
pin 12 of IC U12, check waveform at pin 9 of IC U12. If
waveform is present at pin 9 of IC U12, check IC U12.
If waveform is missing at pin 9 of IC U12 check VDG IC (U7).
is
missing
at emitter of Transistor
pin 12 of Video Mixer IC (U12).
If
10
SOUND
200,200:
While program
1
and 14
IC(U4).
If
is
GOTO
10
running, check for pulses at pins
of Buffer IC (U2).
If
pulses are present at pins
U2, check for pulses at pins
3, 5, 7, 9,
pulses are missing, check PIA
3, 5, 7, 9, 11
2, 4, 6, 10,
and 14 of IC
12 and 15 of IC U2.
If
pulses are missing, check IC U2. If pulses are present at
pins 2, 4, 6, 10, 12 and 15 of IC U2, check for pulses at pin 14
of Analog Multiplexer IC (U9). If pulses are missing at pin 14
of IC U9, check Capacitor C52 and Resistors R10 thru R15
o
o
and R72.
If pulses are present at pin 14 of IC U9, check for
pulses at pin 10 of IC U9. If pulses are missing at pin 10 of
IC U9, check for a logic Low at pins 6 and 7 of IC U9. If pin 6
or 7 of IC U9 do not read logic Low, check PIA IC (U8). If
pins 6 and 7 of IC
U9
are correct, check IC U9.
If
pulses are
present at pin 10 of IC U9 check adjustment of Sound Coil
on RF Modulator, see "Miscellaneous Adjustments".
30
>
oo
(L4)
in -r
Dots are missing from alphanumeric characters. Check IC
KEYBOARD
U7.
Wrong characters appear on Monitor
screen. Check for
pulses at pins 2, 5, 6, 9, 12, 15, 16 and 19 of Latch IC (U6). If
pulses are missing at any pins, check IC U6. If pulses are
present at IC U6, check IC U7.
Keyboard dead. Check keyboard Connector (P6) for good
connections. If connector checks good, check for pulses at
Decoder IC (U11). If pulses are missing, check IC
pulses are present at pin 11 of IC U11, check PIA IC
pin 11 of
U11.
If
(U8).
VIDEO GRAPHICS
One
or
One key
is erratic or dead. Check bad key for continuity.
key checks bad, clean key contacts and recheck key.
more Graphics modes do not work. Type
in
and run
following program:
A group
(P6) for
10FORX = 0TO4
PMODE X: SCREEN
30 NEXT X: GOTO 10
20
ICU8.
More than one letter appears on Monitor screen when a key
is pressed. Check for shorted keys or keys that are stuck
that are available. While
program
is
five
Graphics
and 35 of the VDG IC (U7). If
pulses are missing, check PIA IC (U4) and Dynamic RAM
Controller IC (U10). If pulses are present, check IC U7.
COLOR
Check 3.58MHz waveform at pin 33 of VDG IC
waveform is missing, check Dynamic RAM Controller IC (U10). If waveform is present at pin 33 of IC U7,
check waveforms at pins 8 and 10 of Video Mixer IC (U12).
The waveform at pin 10 of IC U12 should look like the
waveform at pin 8 with an amplitude of .3V peak to peak. If
waveform is present at pin 8 and missing at pin 10 of IC U12,
check Capacitor C42 and Resistor R18. If waveform is missing at pin 8 of IC U12, check IC U12.
No
Color.
If
down.
running, check
for pulses at pins 27, 29, 30
(U7).
of keys do not work. Check keyboard Connector
good connections. If connector checks good, check
X
The program continually switches between
modes
If
CASSETTE
Cassette motor does not turn Off. Check for 0V at pin 39 of
PIA IC (U4). If the voltage is not correct, check IC U4. If
voltage is correct at pin 39 of IC U4, check for 5.0V at collector of Relay Driver Transistor (Q4). If voltage is not correct,
check Transistor Q4. If voltage is correct at collector of
Transistor Q4, check for possible sticking contacts in Relay
K1 and check Capacitor C80 and Zener Diodes CR9 and
CR10
for possible shorts.
Cassette motor will not turn On. Type in and run the following Basic program. The program turns On Cassette Motor.
10
POKE
65313,60
r£
M
o
at iS
» -.
—l
o
09
o
TROUBLESHOOTING
After running program, check for .9V at pin 38 of PIA IC (U4).
If voltage is not correct at pin 38 of IC
114, check IC U4. If
voltage
is
correct at pin 38 of IC U4, check for
tor of Relay Driver Transistor (Q4).
If
voltage
.1
is
V
at collec-
not correct,
check Transistor Q4, Diode CR7 and Relay K1.
(Continued)
14 of IC U14.
IC U14.
If
If pulses are missing at pin 14 of IC U14, check
pulses are present at pin 14 of IC U14, check
voltage at pin 8 of IC U14 while operating the joystick. The
voltage should vary between OV and 5V. If voltage reading
is not correct, check Capacitor C52 and Resistors R10 thru
R15 and R72.
Programs can not be saved on cassette. Type in and run the
following Basic program which continuously saves itself to
cassette.
10
CSAVE: GOTO 10
While program
is running, check for pulses at pins 5 thru 9
pulses are missing at pins 5 thru 9 of IC U4,
check IC U4. If pulses are present at pins 5 thru 9 of IC U4,
check for pulses at pins 4, 6, 10, 12 and 15 of Buffer IC (U2).
If pulses are missing at pin 4, 6, 10, 12 or 15
of IC U2, check
of IC U4.
If
If pulses are present at IC U2, check for
a 1 V peak to
peak waveform at pin 5 of Connector P5. If waveform is
missing at pin 5 of Connector P5, check Capacitors C52 and
C82 and Resistors R41 and R42.
IC U2.
Joystick buttons do not work. If right joystick button does
not work, check for a logic Low at pin 2 of PIA IC (U8) while
pressing right joystick button. If reading is correct, check
IC U8. If reading is not correct, check Coil L2, check pins 3
and 4 of Connector P3 for good connections and check joystick button for continuity. If left joystick button does not
work, check for a logic Low at pin 3 of IC U8 while pressing
joystick button.
If reading is correct, check IC U8.
If
not correct, check Coii L3, check pins 3 and 4 of
Connector P4 for good connections and check joystick button for continuity.
left
reading
SERIAL
is
I/O
PORT
(Connector P2} does not work. Disconnect
any equipment connected to serial port and connect a
jumper from pin 4 to pins 1 and 2 of Connector P2. Type in
Serial I/O port
Programs cannot be loaded from cassette. Inject a 4V peak
to peak 1000Hz square wave at pin 4 of cassette Connector
(P5). Check for pulses at pin 13 of IC U14.
If pulses are
missing, check voltages and components associated with
pins 10, 11 and 13 of IC U14. If pulses are present at pin 13
of IC U14, check PIA IC (U4).
.and run the following Basic program.
10 POKE 65312,0
20 PRINT "0 OUTPUT
ON U4.PIN 3"
30 PRINT "PIN 40=";(PEEK(85313) AND 128)
JOYSTICK
40X = PEEK(65312)
Joysticks do not work. Type
program
10
to
check operation
in
of joysticks.
FORX = 0TO3
90X = PEEK(65312)
20N(X) = JOYSTK(X)
30 NEXT X
100 PRINT "PIN 10=";{PEEK(65314)
AND 1)
110FORT = 1 TO50:NEXTT:CLS:GOTO10
PRINT "RIGHT JOYSTICK HORIZONTAL = ";N(0)
PRINT "RIGHT JOYSTICK VERTICAL = ";N(1)
PRINT "LEFT JOYSTICK HORIZONTAL = ";N(2)
PRINT "LEFT JOYSTICK VERTICAL = ";N(3)
80PRINT "RIGHT BUTTON = ";(PEEK(65280) AND 1)
90 PRINT "LEFT BUTTON = "; PEEK(65280) AND 2)
100 FOR t = 1 TO 100:NEXTT:CLS:GOTO 10
40
50
60
70
The numbers that appear on Monitor screen for joystick
horizontal and vertical positions should vary from
to 63
while the joystick is being operated. The numbers that appear for the joystick buttons should change to the numberO
whenever the button
is
pressed.
Check the
tions.
joystick Connectors (P3 and P4) for good connecWhile program is running, check for pulses at pins 19
and 39 of PIA IC (U8). If pulses are missing at pin 19 or 39 of
IC U8, check IC U8. If pulses are present at pin 19 and 39 of
IC U8, check for pulses at pin 10 of Decoder IC (U11). If
pulses are missing at pin 10 of IC U11, check IC U11. if
pulses are present at pin 10 of IC U11, check for pulses at
pins 4 thru 9 of PIA IC (U4). If pulses are missing at pins 4
thru 9 of IC U4, check IC U4. If pulses are present at pins 4
thru 9 of IC U4, check for pulses at pins 2, 4, 6, 10, 12 and 15
of Buffer IC (U2). If pulses are missing at pin 2, 4, 6, 10,
12,
or 15 of IC U2, check IC U2. If pulses are present at IC U2^
check voltage at pin 9 of Analog Multiplexer IC (U9) while
operating joystick. The voltage should vary between 0V and
If voltage does
not vary at pin 9 of IC U9, check
Capacitors C54, C55, C78 and C79 and IC U9. If voltage
readings are correct at pin 9 of IC U9, check for pulses at pin
5V.
10
50 PRINT "PIN 10 = ";(PEEK{65314) AND 1)
60 POKE 65312,255
70 PRINT "1 OUTPUT ON U4.P1N 3"
80 PRINT "PIN 40 = ";(PEEK(65313) AND 128)
and run the following Basic
The program toggles the serial output pin (pin 3) of PIA IC
(U4) back and forth from 1 to
and reads the Carrier Detect
pin (pin 40) and RS232 IN pin (pin 10) of IC U4. The program
continuously prints results on Monitor screen. When a is
output on pin 3, pin 40 should read 128 and pin 10 should
read 0. When a 1 is output on pin 3, pin 40 should read and
pin 10 should read 1. If readings are correct on Monitor
screen, problem may be in equipment that was connected
to port or in software used to operate the port.
readings are not correct on Monitor screen, check for
at pin 3 of IC U4 while program is running. If pulses
are missing on pin 3 of IC U4, check IC U4, If pulses are
If
pulses
present at pin 3 of IC U4, use a scope to check for pulses
swing from - 10V to + 10V at pin 6 and IC U15. If the
pulses are missing or are not correct at pin 6 of IC U15
check voltages and components associated with pins 1 thru
that
4 and 6 of IC U15 and check IC U15. if pulses are present at
pin 6 of IC U15, check for pulses at pins 1 and 2 of IC U14. If
pulses are missing at pin 1 or 2 of IC U14 check voltages
and components associated with pins 1 2, 4, 5, 6 and 7 of IC
U14 and check iC U14. If pulses are present at pins 1 and 2
of IC U14, check iC U4.
,
O
•r
CM
i
Z
™
NO
r-
1
kn
O
a.
*
z o
< z
S
^c I—
DC K
o<
5 °-
1
CM
NO \0
in
\
IA
CM
ON
a.
UJ
3£
6
< z
to oc
ec
<
d.
ON
-*
1-
z
LU
s
u
o
<
*
in
\
o
o
*—
KN
sx:
CO
d
a,
LU
oc
az
<
to
a.
<3)
1- 1ec
z
<
a.
ior»r>
*L*L^.
CO CO CO
ON
<
<
NO NO
no
*t
—
o
—o
in in
^
in
yj
h-
Z
"=t "^t
Tt-
UJ UJ UJ
i — *—
(
i
CM
*—
CM
o
o
>*r
0_
UJ
3e
*
ON
*—
in
CD
O
UJ
!
KN
—
zzz
1
CM
KN
KN CO
in in
CM
KN
CM
ON
CM >*
KN
CM
ON ON
*:
CO CO
sss
N*r
CO
CM
KN
KN
in
O
O
v
CM ,—
KN
KN CO
in in
O
CDCDO
o
oo
UJ UJ UJ
CM CM *~
KN
KN KN CO
in in
UJ UJ UJ
l_ |_ |_
1
in
in
™—
o_
LU
3e
WW
ql o_ a. a. a.
UJ UJ UJ UJ UJ
31'- 3E JS* J* S-:-.
a. Q- cl a.
UJ UJ LU UJ
3=
< < < on kn
^
— CM
o
o
kn m —
o
o
in in —
\
O "*
On On cm o in
— CO
>
<
<
KN KN NO KN KN
YN/N/^y
CO CO CO CO CO
0_
<<
ON *— KN KN
—
ON CM CM
CM CM »- —
\
W.X.
KlO^f
-^
r^
—*m
CO "*
KN
r- r-
Ww
p-~
v~
fl
KN
KN
n*;
CO
< <- < c.
<
ON KN
o
O rKN ^- CM
O
O
in in
in •CD CD CD © CD
O
OOOO
UJ Ul UJ UJ UJ
r~-
NO
»—
s
I
<f—
CD
O
UJ
< < < a,
<
f- ON KN
O
O
KN r- CM
O
O
m m *™ in -—
KN KN KN
+
ON
NJ
UJ Ul UJ UJ UJ
^ ^f
i
1
1
1
l
KN KN
3- "=3•=t -*
"3-
1
XXX
UJ UJ UJ
1
UJ ui
XX
<<
—
ON "— KN KN
»- ON CM CM
CM CM »-
OO
NO NO
NO CO KN KN
— —
r
i
r-—
—
r
33X
-f
KN
r»
CM
CO
_l
tr
r~
CO
o
in
o
•*
^3"
KN KN KN
CO
UJ UJ
ON ON
CL
+ < <
KN KN O O
——
ON CM CM CO CO
CD CD CD CD CD CD
O
OOOOO
UJ UJ UJ UJ UJ UJ
ON
UJ
CL
CM CM
lO NO
UJ UJ UJ LU UJ UJ
|
|
j
|
|
|
KN
o
o
i-~
CM
CO
_J
*
r^
^
\;
CO CO
N«r
CO CO CO CO
KN KN
r-- rCM CM
CO CO
-J _l
CQ
O
in
o
*
CD
O
LU
— — — — —
z hhhhlzzzzz zzzzzz
NO
»—
UJ
h-
l
"**«»
CM
UJ
h-
KNO
l
I
KN KN KN
t~
CM
CO
O
in
o
it
m
zzz
in
in
O
o
CO CO
*3" *5"
co co co
l
LU
+ < < ON ON
ON — KN KN O O
— ON tCM CM CO CO
»-
r~ r^
^
KN
NO
,— *— T— v-~
CM CM CM CM
»~ v— *— «™
o
o
KN
O
O KN ON <
in in — r- cm
\Winr— r~ * W.
in in vo
o
"— CM KN
^o
_ -^
_ »- ON
l~-
.'.
<;
oO
o
ooo
ON ON ON ON
Nlilt
NNN
r-~
—
O
CM
KN
KN
in
!
^- <;
co r-
Ifl-JOO
p~ r~
\
*—
t
<
<
NO NO
kO
—
o
— in o
in
CDOCD
O
O
O
UJ UJ UJ
d
14J
w
"J-
NO
r-
in
CM CM
in in in
in
i,— S T—
o_ a. a.
LU UJ UJ
3E
3s
<
<
NO NO
»
o
o
m in
<—
<<
kn in in
1
O
CO
"3- *3-
o
o
in in
ON
*—
CO
o
ON
O
»—
CM
.
<
H
<
O
•*
KN
KN
1
KN
v~
^°~
<
o
o
o
—
o
o
ON KN ON
Nl — M
KN KN —
O O CM
*— .— »—
CM
o
T—
CM
CO
NO
CD
«
1
CM
CO
NO
CD
CM
CO
NO
CD
O
OO
UJ UJ UJ
B-* <-» 1
CM
CO
NO
UJ
1-
z
CM
CO
NO
UJ
h-
CM
CO
NO
LU
h-
^r
:
f^-
*
>
oo
mT
|
CD CD
O
O
LU UJ
KN
r^
CM
CO
_l
t
r~
KN
r^
CM
CO
_l
"*
O
r-*
UJ LU
1- 1-
-4
zz
O
UJ
o
z
$0
Q
n
z
o
o.
&
a. z
QC
O
(0
UJ
Q
Q
™
Z
^
"5
Q.
u
CM
in
*—
»~
X
<
CO
-*
*—
KN,
*
«
»
CM
c0 r~
in >*
*-
O
»—
X
§
—
X
5
*
XX
o
s
<<
KN
co
<*
CM KN
^f
-— m co
—
^
in
»- KN
— cm
O
X
X
X
X
Q
Q<<
Q<
<
i~~
v-~
>-*
X
Q
<
"Z.
ON
On
i—
KN
.in
KN
NO
cm
CM
CO
in
KN
o
KN
X
x
<
*
X
s:
<
XX
s s:
<<
•«t
CO
m
«*
><
5
CM
CD
r^
in
**
m
O
KN
X
$
r~
cm
cm
in
it-
"*t
r~-
in
X
X
X
i
0>
to,
"g
2
2
05
to"
CG
CO
~
to
cc
o
Io
»
o
o
—
c
(11
°-
d
K z
aH
u. ec
S <
«
°-
p«»
0)
£
o
o
§
5S
^s
UJ
to
in
0l
o
> z
1-
CO
•*
*
•*
z
<
CM CM
O
co
o co
z On
z ON
z
*—
o
*
CM
CO
CO CM
cm
i
in
"tf
£_
«a=L
CM
"3"
>^
> <—
'^-
o
o
z
CO
CO
cm
^r
cm co in co
in CM KN -a- ON
CM !~- n- KN
co
in
a.
o
— *
zzzt
—
z
<
CM
**
CM
ON ON CM
in CM CM
NO CL CO
o_
UJ UJ
CM ON ON
CM
CM CO CO
CM NO NO
OO
Z-1ZQO
MHScmSS
z
Cl •*
NO
ON KN CL
in in
CO CM
CM
<* ON NO CO
CO
NO CM NO
OO<— —
OO
—zS —
QO
S co
KN
1^
CM KN CL
co i^ r^ r~_J CM
Tf
COCO CO
t~- _J NO NO
CM KN
=> ZD
no
CQ
*
t
*
Z Oo
co r^ s: S
r3
s
UJ
i~"
d
z
x:
+-
KN
o
*
r- r^ CO On
or or or or
oo o o
—
»—
or
o
in
"~
™~
CM
s—
cc
^f
*~
or
o
o
no
r- co
5
o
or or
—
ooo
CM KN
*
o-o-o-
—
3
^r
z>
r^
1!
IO tO
*
*
r- rroo oo
I
I
I
CM CM
I
l
tO IO
*f •*
N<
o
o
o
ON ON
NJ N
r~-
00 CO
to to
"3* *3"=S-
*
I
I
I
LU LU
I
1
CM CM ON ON
CM CM r- l~-
——
~*
—
— t
CM CM LU LU LU LU
CM CM X X X X
I
I
i
i
i
i
i
UJ LU
I
I
CM CM CM CM IO IO
«•* •* -«J<* "*
i
«t
O
Q
tO tO
< zo
s
CM CM
ON ON
cc a:
O<
tO
to
CM
ol
LU
I
l
*-J-
^~|»
I
l
O,
in in to to
oo oo in in cm cm
to to oo 00 ON ON
WW
——
co co no no in in
-J _l — »- NO NO
t "*
NO NO — —
r- r- r» to to
a.
r-~
35i co co co to co
i
I
*}
I
I
I
I
I
I
«J^"
ON ON
r» ri-» r-
o
1
l
I
LU LU LU UJ LU LU
X X XX XX
I
to io
r}-
*
I
I
•* *
LU UJ
XX
QQ
CO CO
_l _t in in to to
"*=»• in in cm cm
r^ r- oo oo on on
CD CD CDCB CD
CM CM CM
oo co in
NO «0 •»
w
to to
to to
ON On
NO
NO
ON
0LU
a n
LU LU
XX
W
to to *4" xj- ^oo oo ON ON *5f
•s. V.
rg
ON ON CM CM CO
NO NO in in _i
in in in
to to to to r~
*
m
^j**"
(vj
CO
_i
^f
r-
Eoi
XX
iO
NO
Oi
0.
LU
—
——
no no r- r~ »NO NO NO NO ON ON
ON ON ON ON
WWW
CM CM
m
_l _l
CM CM to
On on ptn no
tO K^ to
nz
v:
CO CO CO
^
tO ON
r^- -no cm
tO ON
i^ -*c
CO CO
o
o
to CO
ON
^~
cm
ON
r- r»
nz
CO
nz
«i
:
CO
I
O
OOOOO
O
LU LU LU LU LU LU
888
UJ UJ LU
3
(A
0)
to
(A
Z
n
BC
a.
CO
— -.
ON
CM CM
co co
_l _l in in to
>» *3- in in cm
r- i^ oo oo on
LU LU LU LU LU
cm
on
LU
f—
f™**
l""""
ssrtoto
— —
»
-=*-
-
-
t
i
i
K\ Kit rt
oo oo on on r~ r^
CD CD CD CD CD CD
o
LU
ooooo
LU LU LU LU LU
no
NO
ON
CD
no
NO
ON
CD
r~
NO
ON
CD
—
»rNO ON ON
ON »~ -—
CD CD CD
o
ooooo
LU LU LU LU LU LU
o
o
to CO
•*
——*
—o
o — rr- r-
r~-
OCD
OOO OOO
o
o
LU LU
LU LU LU LU LU UJ
r"""
r"*
r""*
co co
s s:
*
—
—
-J _l
**
to
to
>sr
rf
oo oo on on r- rLU LU LU UJ UJ LU
l~
— — — —
I
i
I
I
o
u.
CM CM
O
O
co to
_) _i
**
CN CM
•<*
NZ
NO
_l _l
CM CM CM CM CM CM
CD CD CD CD CD CD
R
aa
to
CM
oo oo in
vo «o ^jLU LU UJ
^*-
CM CM
CM CM
_
I
I
LU LU
oo oo
to to
CO
— — ON
l
tO IO
^£» a^_ 4^. ^j.
""^J*
"^
ON ON
CM CM CM CM CM CM
^f" -t^ ^J"
Q
o
< z
°
t:
DC DC
<
<3"
NO NO
NO NO
ON On
*
t
ON ON
to
to
CM
o_
LU
«* •* in in in in
r~ r— -- >o no
no no no no \o no
t~-
NO
NO
ON
LU
iO
NO
ON
LU
——
f- l-»
NO NO ON ON
ON ON r~ •—
LU LU LU LU
I
hv xt
— — ^t
o——o
r-- r--
r**
CM CM CM CN CM CM
LU LU LU LU LU LU
r-~ p»
LU LU
I- t-
—
— — —
z^
zzzz^
z
I
|
I
[
us
o
"55
"O
3
c
C _,
O *«
c
o
E
a>
o
O
o
®
a.
a
Q
z
<
o
z
u. E
s <
Q-
oo in
p- oo
in in
u
©
a
o
HI
.
cc
^
»
oo
**•
in
to
^
<
X
<
^S
<
o
o
CN
t
>^
<
*
00
in
NO
00
to
CM
*
X
<
s
<
r~
rin
00
00
r~
TT
•
X
<
X
^
*
o
o
to to
XX
o
NO
CM
*
X
s:
<
in
in "*
in >*
in
o
o
to to
XX
O
to
X
£2 33
w
DC
m
"3-
PO
^J.
O
o
z
UJ
a.
.
o
> z
0rcm
CO
NO
to
03 CO
ONI~£L _1
CM CO to IO to
in _i oo oo oo
Tt •* 00 CO 00
CM
l~- vD iO NO
——
QSOQZOOO
SnOSCoSZS
z
co
z
to
o,
O
«- 00 0CO tO CM CN tO
_l_r~.t~.CN
*
co to to r~ o
———
r~-
_i
to
%£££%£
OUNrt
— CO Tt
Z tw
ON ON
_| CM
to to r- o >* to
to to — — r~ _i
•*
•*
s: s:
"3"
_i _i
o
z rS r- to
&
H
O
<
cm
in
«o
o
CM CM CM _i in
S
00 •- — — ON o
i»2SSnj
ON ON QON
Q
r~ r— r- S rZ 00
E
o
c c
a.
CD
to
toooo_ooo_-*z
CN<CMCM<CNNOCM
8°
NOOCMOOCNin<tOCM
—
OOOOOO00-IO
—
2>s:2NONS:c_NQ-*to
+•
to
I
zr~-r-r"-r--r-»cNioo
^J
*^
-s.
.
Sinsico to ft
.
to s: to r~
0> «_W
"»
CO
¥
O
o
cc
<
a.
12
JC
5
UJ
0)
O L
©
OS
co<
— a:
cd_:
+-•*
ID
LU
O
ecu.
o
ON —
Z> Z)
>—
CM
00
5
5
5
no
O
CM CM
3 Z5
rCM
z>
oo
CM
3
PARTS LIST AND DESCRIPTION
When
(Continyed)
ordering parts, state Model, Part Number, and Description
CAPACITORS
ELECTROLYTIC CAPACITORS
ITEM
No.
MFGR.
PART No.
RATING
C17
thru
1
MFGR.
RATING
9pF-35pF
C4
ACC105QJTP
50V
uF
ITEM
No.
PART No.
AC-4926
C19
RESISTORS (Power and
Special)
REPLACEMENT DATA
ITEM
R11
M
R12
R13
R14
R15
R75
WORKMAN
PART
No.
Contains four (4ea) 33 ohms.
COILS
(RF-SF)
ITEM
No.
30
TRANSFORMER
32
MFGR.
FUNCTION
oo
Sw
PART No.
RF Choke (3.3uH)
RF Choke (3.3uH)
L2
L3
NTE
PART No.
AN0281BEE
AN0306BEE
AN0597BEE
AN0359BEE
AN0385BEE
AN0408BEE
ARX0220
10K \% 1/4W Carbon Film
20K \% 1/4W Carbon Film
40. 2K
1/4W Carbon Film
80. 6K \$ 1/4W Carbon Film
162K \% 1/4W Carbon Film
324K 1% 1/4W Carbon Film
Res i stor Network ( 1
R10
(1)
MFGR.
PART No.
RATING
No.
">
go
ACA8059
ACA8059
«
^
O
O -J
31
(Power)
<P
OS
o
REPLACEMENT DATA
RATING
ITEM
No.
SEC.
PRI.
18V AC $
50mA AC
120V AC S
130mA AC
T1
1
SEC. 3
SEC, 4
MFGR.
PART No.
SEC. 2
18V AC i
160mA AC
NOTES
ATA0856
993-0433 (1)
SEC. 5
19V AC a
600mA DC
(1
)
Number on unit.
CONTROLS
ITEM
NO.
R21
R60
(All
waffages 1/2 watt, or
FUNCTION
Video Level
+5V Adjust
RESISTANCE
500
1000
less,
unless listed)
MFGR.
PART NO.
NOTES
AP7156
AP0835
13
PARTS
When
AND DESCRIPTION
LIST
(Continued)
ordering parts, state Model, Part Number, and Description
FUSE DEVICES
ITEM
NO.
MFGR.
PART NO.
DESCRIPTION
DEVICE
F1
.7A % 250V
Fast-Acting
NOTES
HOLDER
AHF1185
AFI176
MISCELLANEOUS
ITEM
No.
K1
R73
R74
R75
R76
R77
SI
S2
S3
XI
PART
MFGR.
PART No.
NAME
Relay
Ferrite Bead
Ferrite Bead
Ferrite Bead
Ferrite Bead
Ferrite Bead
Switch
Switch
Switch
Crystal
Keyboard
Keyboard Cab e
Power Cord
1
AR81 30
2643021801
2643021801
264000301
264000301
264000301
S0852
S0851
S9142
AMX2797
AXX0206
AW2589
AW2587
CABINETS & CABINET PARTS (When
ITEM
Cabinet Top
Cabinet Bottom
Cartridge Door
NOTES
Cassette Enable
Reset
Power
Channel Select
14.31818MHz
Comp ete
1
ordering specify model, chassis
&
color)
PART No.
AZ5844
AZ5845
ADA0337
WIRING DATA
Shielded Hook-up Wire
General-use Unshielded Hook-up Wire
300-Ohm
75-Ohm
14
Input Lead
Input Lead
Use BELDEN No. 8401
8208
Use BELDEN No. 8529
8522
Use BELDEN No. 8225
Use BELDEN No. 8241
or 8421 (Single-Conductor)
(Two-Conductor)
(Solid) Available in 13 Colors
(Stranded) Available in 13 Colors
LOGIC CHART
PIN
NO.
PIN
PIN
PIN
PIN
Ul
NO.
Ul
NO
L
H
21
22
P
P
2
3
4
P
23
24
P
P
3
4
5
P
P
P
5
6
L
L
P
L
P
7
H
P
7
L
8
P
25
26
27
28
5
6
P
8
L
P
P
9
10
P
P
29
P
9
L
P
30
P
10
L
11
P
P
31
P
11
I
P
P
32
P
12
L
13
14
P
33
34
P
P
13
14
*
15
P
35
36
P
P
L
H
1
2
12
H
P
36
P
1?
18
19
P
P
37
38
39
20
P
40
P
U2
U3
NO.
U3
P
21
P
P
P
22
23
24
PIN
NO.
U4
NO.
U4
P
1
L
21
P
P
2
P
3
H
4
L
H
L
22
23
24
H
H
6
L
L
7
L
8
L
25
26
27
28
9
10
L
H
29
30
11
*
31
P
P
L
12
H
32
P
P
16
*
P
13
14
15
16
L
L
L
L
33
34
15
P
P
P
P
L
L
35
36
P
P
H
17
18
P
P
17
18
H
H
19
P
19
37
38
39
20
P
20
L
H
L
H
1
H
L
L
L
40
H
P
P
P
P
P
H
L
H
1
PIN
NO.
PIN
PIN
U6
U7
NO.
U7
NO.
PIN
U8
NO.
U8
L
H
H
H
21
P
22
23
24
P
P
P
P
P
P
H
L
21
P
2
3
P
P
P
P
P
P
P
P
P
2
3
4
22
23
24
5
P
25
26
27
28
P
5
P
6
L
7
H
H
H
8
P
P
P
P
8
H
25
26
27
28
9
P
29
L
9
H
29
10
30
P
30
11
31
L
L
10
11
L
P
11
P
P
32
P
12
P
P
31
12
13
14
P
P
P
P
P
33
34
35
36
P
13
14
33
34
I
15
P
P
P
P
P
P
P
P
16
P
35
36
P
P
P
H
37
38
39
17
18
P
P
P
P
L
19
H
40
P
20
L
H
37
38
39
20
P
P
P
P
P
19
P
P
40
P
1
6
7
35
16
1?
18
P
P
P
1
4
32
H
H
P
P
P
H
L
15
LOGIC CHART (Continued)
PIN
PIN
PIN
U10
NO.
U10
P
P
P
21
P
2
3
4
P
22
23
24
P
P
P
5
P
25
6
P
P
P
26
NO.
U11
NO.
U16
U20
U21
U22
U23
U24
L
P
P
P
1
P
1
P
L
L
L
L
2
P
2
P
P
3
P
4
P
P
P
P
P
P
4
P
P
P
P
3
P
P
P
P
P
5
L
H
5
P
6
6
P
P
P
P
P
27
P
7
P
7
P
P
P
P
P
28
P
8
L
8
P
H
P
P
29
P
P
9
10
H
H
9
10
P
30
L
P
P
31
P
P
11
P
11
P
P
12
H
12
P
P
P
P
P
P
33
34
P
13
14
P
13
14
P
P
35
36
P
P
15
16
P
P
P
P
L
37
38
39
P
17
P
P
18
19
40
H
20
H
NO.
U25
U26
U27
U28
NO
U28
PIN
NO
1
L
21
P
22
23
24
P
P
3
P
P
P
P
P
H
4
H
L
L
H
1
7
8
9
10
11
12
13
14
15
16
17
18
19
20
32
PIN
P
H
15
16
PIN
P
P
P
P
P
H
H
H
H
H
H
H
H
H
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
L
P
P
L
L
L
P
P
P
U29
L
L
P
P
P
P
P
P
P
P
5
P
P
P
P
5
L
6
P
7
L
8
H
H
H
P
P
P
L
P
P
P
6
7
P
P
8
P
9
H
P
H
H
P
10
P
P
P
P
9
10
11
12
P
P
P
P
13
14
P
P
15
P
L
17
18
19
20
1
2
L
12
P
P
#
*
P
P
P
13
14
L
H
P
P
P
P
P
P
P
P
L
L
P
P
P
P
P
11
P
P
P
P
2
3
4
16
16
PIN
WO
P
P
L
P
P
P
SCHEMATIC NOTES
-*-
Circuitry not
e
4r
rrtr,
<j
See parts
Ground
Item numbers
in some versions
some versions
used
— Circuitry used
in
rectangles appear
in
justment instructions.
Supply voltages maintained as shown
list
in
the alignment/ad-
at input.
otherwise.
Voltages measured with digital meter, no signal.
Controls adjusted for normal operation.
Terminal identification may not be found on unit.
Capacitors are 50 volts or less, 5% unless noted.
Electrolytic capacitors are 50 volts or less, 20% unless
Waveforms and Logic probe readings taken with
computer turned On, no keys pressed, unless otherwise
Resistors are
noted.
Value
ChaSSIS
Common
tie point
Waveforms and voltages taken from ground, unless noted
noted.
Voltages,
Waveforms taken with
triggered scope and
Sweep/Time
switch in Calibrate position, scope input set for DC
coupling on reference voltage waveforms. Switch to AC
input to view waveforms after DC reference is measured
when necessary. Each waveform is 7 cm. width with DC
reference voltage given at the bottom line of each wave-
in
(
)
V2W
used
or less,
in
some
5%
unless noted.
versions.
Measurements with switching as shown, unless noted.
Logic Probe Display
L
= Low
H = High
P = Pulse
form.
p-p reading at the
Time in /isec. per cm, given with
each waveform.
end
of
*=Open
(No
light
On)
LINE DEFINITIONS
A0 THRU A15
CART
CAS
CASS MOT
CASS OUT
CASSDIN
CD
CSN
CTS
DO THRU D7
Address
Cartridge Presence Interrupt
Column Address Strobe
Cassette Motor
Cassette Output
Cassette Data Input
Status Interrupt Input (RS232C)
Cartridge
Cartridge Select Signal
Data
Display Address Ero
DAO
Clock, 1/16 Master Clock,
E
H1
HALT
HS
IRQ
CPU RAM Addressing
ROM
EN1
EN2
FIRQ
FS
Sound
.
Enable
ROM Expansion Enable
Fast Interrupt Request, Does Not Maintain Registers
Sync
PIA CSO and CS1
MAO THRU MA6
MDO THRU MD7
Nonmaskable
NMI
Halt
CPU
Input
Horizontal Sync
Interrupt
3D
>
O
5
0)
I
>
O
Interrupt
Peripheral Interface Adapter Ero
PIAO
PIA1
Peripheral Interface Adapter
Q
One
Clock, 1/16 Master Clock,
Leads E Clock by Ninety Degrees
R/W
Read/Write
Row Address Strobe
RAS
RESET
RS232
RS232
Reset
IN
SCS
SEL 1, SEL 2
SLENB
Field
Chip Select,
Memory Address
Memory Data
SND
VDG CLK
WE
RS232 Interface System
RS232 Interface System Input
Spare Cartridge Signal, Selects Address Space
PIA Select Outputs, Joy Sticks or Sound
w
O
O
—1
33
00
o
Select Enable, Disables Internal Selection,
Utilities Unused Memory
Sound Source in Cartridge
Video Display Generator Clock
Write Enable
Request
17
SAFETY PRECAUTIONS
1.
Use an
2.
Maintain
isolation transformer for servicing.
AC
line voltage at rated input.
Remove AC power from the Computer before servicing or installing electrostatically
ES devices are integrated circuits and semiconductor 'chip" components.
3.
sensitive devices.
typical
Examples
of
Use extreme caution when handling the printed
4.
circuit boards. Some semiconductor devices can be
damaged easily by
any electrostatic charge on your body by touching a known earth
ground. Wear a commercialavailable discharging wrist strap device. This should be removed
prior to applying power to the unit under test.
static electricity. Drain off
ly
5.
Use a grounded-tip, low voltage soldering
6.
Use an
7.
Do not remove
8.
Do not use
Isolation (times 10) probe
iron.
on scope.
or install board, floppy disk drives, printers, or other
peripherals with
power On.
freon-propelled sprays. These can generate electrical charges
sufficient to
damage semiconductor
9.
The Computer cabinet
10.
Instructions should be given, especially to children, that objects
should not be dropped or
cabinet. This could cause shock or equipment damage.
086 the
11
"
is
equipped with vents to prevent heat build-up. Never block, cover,
or obstruct these vents.
C ° mpUter
,0 Wa,er
waLTsTr
12.
ex P° sed t0 water tum the unit
.
AC
off.
pushed
into the vents of the
Do not place the Computer near possible
outlet for long periods of time.
Remove AC
plug from
AC
Never use liquids or aerosols directly on the Computer. Spray on
cloth and then apply to the Computer cabinet. Make
is disconnected from the AC power line.
sure the Computer
18
!f
'
Never leave the Computer unattended or plugged into the
outlet during lightning storms.
13.
devices.
PSNOUTS & TERMINAL GUIDE?
SC
SN74LS138N
MC1372P
^^
A
vcc
1
SELECT
CLOCK OUTPUT
RF TANK
2
OSCILLATOR
INPUT
SF TANK
a
w
c
yi
DUTY CYCLE
ADJ
62A
Y2
8ND
-<
IDENT
1
16
IDENT
=116
=115
3C
314
313
312
4C
SC
RF MODULATOR
OUTPUT
61=
COLORS
T3
639
ENABLE
vs
V7
INPUT
INPUT
COLOR A
INPUT
Y
6ND
TOP VIEW
U12
ys
MC14529B
TOP VIEW
U11
DECODER
STRBX
SN741S244N
TOP VIEW
S7JBY
XI
YO
X2
YI
X3
Y2
A
YS
NC
FREQUENCY
COMPENSATION
CURRENT
SENSE
V*
INVE&TIN6
INPUT
VC
VCC
XO
MC1723CP
CURRENT
LIMIT
39
U3,U28
CHROMA NODUUTOR
OUTPUT
VIDEO MODULATOR
NC
310
U2,U27
TOP VIEW
LUMINANCE
COLOR REP
Y4
St
CHROMINANCE
INPUT
INPUT
5
111
7C
sc
a
V
GNP
z
U9
SOUND SELECT
TOP VIEW
33
N0N-INVLRT1N0
>
VOUT
INPUT
§2
oo
D
MM116N-3GP
VREF
VZ
V-
NC
13
Ut3
IS
IS
D OUT
14
IN
9
MITE
4
RAS
A6
IS
S
AO
AS
12
s
A2
A4
11
7
Al
AS
10
12
REGULATOR
TOP VIEW
SND
CAS
VBB
1
2
11
VCC
vpp
a
U20 THRU U26
RAH
TOP VIEW
V
CLEAR
2
3
ia
a
6
a EAR
9
A
V
a
a
m
SD
CK
A
20
19
18
9
f
L
CK
CLEAR
20
90
aEAR
CK
ID
4
S
c1
vc!C
A
V
\
r
CK
aEAR
CLEAR
CLEAR
70
70
a
SO
17
IS
15
vss
007
006
CSS
ODD
15
DD1
ra
DD2
RP
DOS
A/8
DD4
J/S
DOS
OK
CM
INV
6
Int/ext
A
6M0
H3
SMI
0A5
Y
<y
7
a
3
3D
4D
D
D
40
CK
CK
9
A
9
A
A
/
I.
h
V
CK
CLEAR
c
<s
SD
CK
aEAR
^1
G ID
D
60
<vl
50
aaX
12
1!
DA6
6H2
DA7
DA4
DAS
DAS
VCC
DA2
DA9
DAI
DA10
DAO
DA11
TOP VIEW
All
VCC
A10
A12
AS
A13
AB
AM
OSC IN
A15
OSC OUT
Z7
VCLK
Z6
DAO
75
HS
24
IS
Z3
CAS
Z2
RASO
Z1
OH
S *>
6o
O
S
P3.P4
EXTERNAL VIEW
FRONT VIEW
U7
VIDEO DISPLAY
GENERATOR
TOP VIEW
MCSB21P
zo
E
SO
R/5
SI
AO
32
A1
A7
A2
AS
VSS
PA0
CA1
AS
«HD
A4
nmT
TSC
ifto
LIC
CA2
PA1
1R0A
PA2
irbb
reset
7755
AVMA
BS
PAS
RSO
BA
PA4
RSI
PAS
RESET
PAS
DO
PA7
01
PBO
D2
PB1
03
VCC
E
AO
BUSY
Al
m
A2
DO
A3
01
A4
02
AS
03
AS
04
A7
OS
AS
OS
D4
05
PBS
OS
PB4
D7
P65
A3
HALT
VSS
PS2
DA12
US
FLIP/FLOP
SN74LS783N
v^
14
13
>
MC680SEP
AN48227
SN74LS273N
Cfl
mX
W6
E
PB7
AS
07
A10
A1S
All
AM
CS1
cm
CS2
etc
CSO
A13
A12
R/W
VCC
U1
U10
MULTIPLEXER
TOP VIEW
U4,U8
PIA
TOP VIEW
MICROPROCESSOR
TOP VIEW
19
POWER SUPPLY BOARD
20
.
|
10
12
11
I
13
14
^
15
|
17
16
18
2!
IS
22
I
23
24
25
27
2S
28
I
!
,
:
'"""""""
B
I
ml
?K
W
Wr
C
j;
I
«
r
E
,:.>:
F
J?
•
jKir
*
•
u*
,.
:
E
F
I
"iraffai
:l
G
:
£
H
j
14
•ni
1
s2
oo
Pi
*2
H
,'"^yi^.*t;&g,»i
I
r
7
J
T~
.
r
J
'-#!;*£
K
K
•
'.
-a-
'J=
*
L
•i M
N
,£.
'
N
1
till
r
,
p
Q
2
MAIN BOARD
4
j
3
j
4
|
5
j
A Howard W. Sams icianil:fj«am
8
[
8
7
I
Phnto
9
I
|
10
|
11
|
12
|
13
|
14
|
15
|
16
|
17
|
18
|
19
|
20
|
21
|
22
|
23
|
24
|
25
?6
27
28
MAIN BOARD
21
02
C
E
8
U9
U15
U14
Q4
U8
U4
Q1
U6
U12
U7
U28
U2
U3
U16
U1
U10
o
o
CO
oo
?!
ro
U18
U19
5.0V(A)
-12,0V
ARROWS ON
MAIN BOARD
22
* HowaMl "• Ssm *
IC'S INDICATE PIN
HE33HZ51 p,™ te
1
•5.0V
5.0V{B)
11JV
UNLESS NOTED
MAIN BOARD
3
*
MPS3904
'J»L 01 VIDEO AMP
MV
.5V.
IH12B5-8
'3.4V
"I.
^^
Trarr
£
MODULATOR
SOUND
9
1500
14.
SN74LS273N
R5232
SERIAL
INPUT/
Ef
R47
'
P2 11^ 48
TO
MONITOR
CHANNEL
e
UB
£
IOOjiF]
Ti
ignr
R21
VIDEO
CR16,
Gi>
— mr —|
LEVEL
500
m
^
5.0V CM
40<i6i
«-*
17
4700
S3
CHANNa
S.OVCA)
SELECT
J"
,6V
—
3.8V
107
Ml
CHS
10
R44;
OUTPUT
PORT
C12J
13
VDC
LATCH
l
*3.7V
2V
VD6 CUC
fr«
14
17
120VAC
9
130 •*
OAO
PI
TI
**=;
2.5
.01 i
POLARIZED
4
22.5;
2.6
"~eel
10o£j
-1
1
C461
*
i
I
1
GT"S«
?1 CSSl CSBl C7ll C491
4
C32l
-«*•-
'I
''I
''I
''I
'1
''I
19VAC
RAS
PIA1
—
.02-r
02
•
"^n
—
M—
jjjf
3
o
MC14050B
CAS50IN
(12
^
J
CASS HOT
T4
,av
18
'I
sa
w*
RS232 IN
OVMULTIPLEXER
SEE PINOUTS, TERMINAL
GUIDES AND SCHEMATIC
NOTES ON PAGES 17 AND
03
19
TIP29
RE6
''I
"'J
y
10
R65:
'
•9BO'
5.0V CM
PHOTO CIRCUITRACE «
HI
NC1723CP
U13ERR0R AMP
11
~l 3 I SOURCE
7.1V
11.9V
T
R61
1200
4700
C11
jH
1000
CABLING.
32K
IS*
1]
5.0V GO
HEAVY LINES REDUCE
USE OF MULTIPLE LINES
A PHOTOFAa STANDARD NOTATION SCHEMATIC
Howard W. Sams & Co.,
Inc.
.001
100V
1QX
iT
C24
wnHHnHEng
©
13
R64
SCHEMATIC CIRCUITRACE -[77]
TT
4.9V 11.8V S.8V
5 12
R57
H2
''I
aj'ajsj^t^t
10.4V
R72
100*
J5
-'i
|
e
7F NC
T5i
2
r
1«C IX
NC-
•a
jrOVANALOS
9 RIO
40
—r-m^
;
-
SOURCE
20* IX
CD
i
CSsX
T
SS.0VCA)
1*
6R11
S.WW
-'i
-
is
6R12
tV
C72J.
'j
-
80. 6X IX
IOC,'
40.*
C29_Lc66.L
O0
•
1
~"»1 C2Sl
C47l C63±
CIO-
GR13
f
lOOOO^F*"
10
CASS OUT
CART
^SOURCE
-7JWX
.ooif
FIRO
1986
J4
RADIO SHACK TRS-80
MAIN BOARD
MAIN BOARD
23
24
MODEL 26-3002
25
1
1)
F
si
C
ill
slls
CD
u
n
m
U
0)
(O
\l
0)
I/)
p
u
O
u
n
z
< o
<
CO
o <
°-
CO
CN
)
CO
<)
rv
t
>^
5
lill
o
^r
o
o
oo
n
c
CD
c
i
C"
.-*-
s
"n
c
a
CL
o
(J
0)
b
>
n
</>
co
»
<
en
o
c
n
c F
u
u
E ID
(i>
<D
in
(/i
o
U
o
tn
t
/
c
o
a
u
o
za
<
Q_
s?=s
n
c
c
r
OT.Q
b
=>
H
O
<
U1
u o
c
o
—c
0)
o CT)
S £
S2
u
ss
s
oj
(A
E
a
c
5
/
sjIhh
E
o
a
-p -;
u
a
(1
2?
01
a
o
Hi
b
^1
c
o
U
CD
b
U
"5
5
n
u
u
u
u.
ft'Kllli
5
a
>-
a:
z
(1)
CO
o
a)
».
-
?
en
"O
3
o
CO
CO
I <
>
O
O
"t
D
lili
"S
o
rr
^;
55
-Q
(/)
E
E
§
O c
a
o
2|
Q
CL
D
i
«5
<
1
O
O
E
U
to
x
n
di
u
c
\
F
0)
S
>
ga z
r
ilil
a
.
_gj
<
-I
rn
a
O
.-1
a_
c
£
i_
1/5
O
i/>
a
n
IN
N
<J
o
_c
s
3
C
(h
rn
OQ
0)
O
'€"!
a
0)
B
jllf
<
S Q.
O uj
Q.
1.
<
a
i-
^j
n o>
c
LU ._
i=
<
(>
u
n
.S
_C -=
=
o
D "D
>^
c
o
"O
o
X
in
/=
O
o
in
U
o
L)
u
a;
c/>
_c
0J
l/l
a.
-a
U
-o
^r
LU
o
s
>~
1)
1)
O
> z
>»
o
D
5
E
o
w
U
t/i
03 LJ
n
c
III!
n
0)
~o
o
u
()
S
i
o
5
lllil
«
S
o
O
Cj 00
U o
,0
SI
£
°
*Z
c
5 8
o _c
~o .t
o *
oo
>
o
Jll
(1)
(/»
a)
J
§
E
a
D c
E D
_0)
_D
a
O
> a>
c
o o
•^
£
o-
a
>
a)
U
<
_c
Q_
c <*
a>
<"
en
c
o
o
V>
D
E 5
2
CD
J
•>
"D
>> •—
c
</)
o
It
1
o
1
<D
_Q
O
o
0)
u]
0)
M
<!
CO
U
U
o
Q£
O
u
c
r
I
l
a
V
)
0J
c
u
•il
i/1
m
T3
^
T3
(/l
CT
^
tr
(1!
0)
i-
u
o
rr
F
to
0)
5
<
1
U
<n
0)
X
tn
oO
5
-i a.
x
—6
a. z
^<M-n
Q_ CL 3-
z
—
o
•
Q_ -Z
^K£
o
oo
n
_3
CL LL tL
•
_
.-,i
v_
CL
x
0)
_o
u_
-1 0-
n
o
tn
13
JH
uo
5
UO
c
()
0)
E
-in
o
en
o
.y
3
t—
x
en
u
D
n
c
'
n
u
a
-)
o
0)
tn
3
-J a,
LL
o
_^
O
O
O
o
>-
0)
(1)
3
e
(1>
^
o
"5
r
-I CL
<D
II
c
u
o
c
>
m
>>
§1
O £
i 'I
CJ
oo
>X>
T3
J
x
tD
O
I
o
T3
0)
a.
'I
1
^
-1 CL
oo
oo
CO
n a
-^
<D
T
o
O D
-Q
S3
'I
en
5"?
i5
^
i
T 'I
"
o
(D
s
*O
o
"a
'I
u
0)
D
T3
r-i
u
<i)
u
t/3
u.
c
O
CL
E
o
Z
—o
z:
0.