Sams 26-3134, 26-3136, COLOR COMPUTER 2 Technical Service Data
CC15
08970
COMPUTER:
RADIO
SHACK
TRS-80
COLOR
COMPUTER 2
MODELS
26-3134,
26-3136-
TECHNICAL
SERVICE DATA
FOR
YOUR
COMPUTER
SAM
S
COMPUTERFACTS'
RADIO
SHACK
COLOR
MODELS 26-3134, 26-3136
COMPUTER
2
CM
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PRELIMINARY
This
data provides the user with
which is designed
puter malfunctions.
£
m
n
<6
<*
<*
n
«
H
£
s
Check ail interconnecting
correct
hookup before making
Disconnect all peripherals
Computer to eliminate possible external
TEST
TEST
Digital
Logic Probe
Frequency
TV
EQUIPMENT
EQUIPMENT
Volt/Ohm
Counter
Monitor
SERVICE CHECKS
for quick isolation and repair
Meter
a time-saving service tool
cables for good connection
service checks.
except the Monitor
malfunctions.
AND
TOOLS
of Com-
and
from the
TOOLS
Low Wattage
Desoldering
Contact
Phillips
Flat
Blade
IC Insertion and
Alignment
Soldering
Equipment
Cleaner
Screwdriver
(non
Screwdriver
Removal
Tools
GC
Iron
spray
type)
Tools
Electronics
14,
9440
16, 24
and
40 pin
SAMS
The
listing of any available
constitute in any
Howard W.
replacement
from
information
manufacturers
case
Sams
& Co.,
part. The
furnished to Howard
of the particular type
REPLACEMENT
IDENT
D3
D4
IC1
IC2
IC3
IC5
IC7
IC8
IC9
IC11
IC13
IC14
thru
IC21
IC22 MX6198
Q1
R2
RY1
SW1
T1 ATA
recommendation,
a
Inc..
numbers of these
PART NO.
DX2321
DX2321
MX6201
AMX4578
MX6202
AMX4227
MX6211
AMX4575
MX5560
AMX4583
MX6200
MX6199
2SD526
N0001EGE
AR8166
AS2900
1056 Transformer,
Howard
4300 West
replacement part
a5
warranty or guaranty
to the
quality
parts have been compiled
W. Sams
of replacement pari listed.
W.
62nd Street,
herein does not
and suitability of such
& Co.,
PARTS
DESCRIPTION
Diode,
30D1
Diode, 30D1
IC,
SC77527P
IC,
MC6821P
IC,
SC77526P
IC,
SN74LS273P
IC,
SC67331P
IC, MC6847P
IC,
MC6809EP
IC, SN74LS138N
IC,
804236
IC,
RAM
MB8118-12P
IC,
74LS783
Transistor
Resistor,
Relay
Switch,
Sams
Inc.,
Power
& Co.
P.O. Box
by
the
by
.1
ohm, 1W
Reproduction
content,
respect to the
%
4300
Printed
AND
Power
1986
DESCRIPTION
7092, Indianapolis,
or
use,
in any manner,
use of the information contained herein.
Howard W. Sams
West
Street,
62nd
in U.S. of America.
Indiana 46206
without express
is prohibited. No patent liability
P.O. Box 7092. Indianapolis,
Co.
&
permission, of editorial
86CC14969
U.S.A.
is assumed with
Indiana
46206 U.S.A.
DATE
or pictorial
4-86
PRELIMINARY
SERVICE CHECKS
(Continued)
CASSETTE
POWER
RESET
(SA)e
SOUND
RF
MODULATOR
(3A)(4B)
CHANNEL 4
<S>
CHANNEL 3
120MC
R2
OB)
s.ov
source
/
IC1
(IS)
©
6a)
SALT
o
PULSES
IC7
PI
A
C6A (6D
@
©
PULSES
@©@
(g)
4
7
8
^9
IC2
P1A
KEYBOARD
3
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33
INTERCONNECTING
DIAGRAM
II
INTERCONNECTING
DIAGRAM
VIS
PRELIMINARY
SERVICE
CHECKS
(Continued)
©
©
MATCH
THE
COMPUTER
(A) Check
THE
NUMBERS
DEAD
for
A2. If the
and
A2, check
17.5VAC
voltage
open winding.
tween
the
power cord.
voltage
5.0V
check
of Transistor
at the
emitter
voltage is
Transistor
of the
center
winding and
Resistor
Check
secondary
an
open
(B) If the
check for
ing,
emitter
ent
(C) If the
check
D3 and D4.
If all
"Microprocessor
MICROPROCESSOR
(A) Computer
and
check
of the CPU
35
the
is
SAM IC (IC22)
NUMBERS
ON THE
between
is missing
Power
Transformer
Also
check for
tap of the
Connector
is correct
at the
voltages
dead. Check
at
5.0V source.
R2, check
Q1. If
of
Q1,
missing
Q1 and
Power
are
Operation"
OPERATION
IC (IC9).
SERVICE
ON THE
SERVICE
Connectors
at Connectors
(T1) for an
continuity
Power
Transformer
A3. Check
Connectors
the voltage
check
at the
IC1 . Also
Switch
correct,
section.
for
If
pulses are
by substitution.
A1 and
If
5.0V is miss-
for
5.2V at
Resistor R2.
emitter
check
(SW1).
refer
pulses
CHECKS
INTERCONNECTING
CHECKS
A1
is
pres-
of
Diodes
to the
at pins
missing,
and
A1
be-
for
A2,
the
Q1,
34
TO
BE PERFORMED.
(C)
SOUND
©
(A) No
(B) If
(C) If the pulses
KEYBOARD
(A) Keyboard
DIAGRAM
Colors
are not
3.579MHz
quency is not
Clock
Trimer
ments".
sound.
gram:
10 SOUND
Check for
pulses are present,
Sound Coil,
pulses are not
pulses
present,
check
PIA IC
tor
(CN2) for
correct. Check
at pin
correct,
TC1,
Also check
Type in and
200,200: GOTO 10
pulses
see "Miscellaneous
at pins
present
3
check
IC3
are missing
(IC2) by substitution.
is
dead. Check the
good
AND PHOTOS
7 of SAM IC
see "Miscellaneous
IC22
at pin
check
thru
8 of IC3. If the
by substitution.
connections.
for
(IC22).
check
the
by substitution.
run the
1 of DAC IC (IC3).
the
adjustment of the|
Adjustments"
at pin 1 of
pins
at
3
keyboard
WITH
a frequency
If the fre-
adjustment
Adjust-
following pro-
If the!
IC3, check
thru
pulses
8 of IC3,
Connec-
fori
are|
of
of
(B) If
check for
when
data pulses
(C) If data
and
thru IC21),
(IC13)
©
VIDEO
(A) No video.
(IC8)
(B) Dots are
Check (IC8)
Wrong
(C)
Latch IC
COLOR
©
(A) No color. Check for
(IC22).
1C22 by
If
(B)
the 3.579MHz signal is present
check the
pulses are
the
then
and the
present
data
Computer
present,
pulses
suddenly
ROM
by
substitution.
Check the
RF
missing
by substitution.
characters appear on the screen. Check
(IC5) and IC8
the
If
3.579MHz signal is missing, check
substitution.
at pins
pulses on
is turned
check
appear on
stop, check
IC(IC12)and
Video
Modulator
from
alphanumeric
by
3.579MHz at
and
34
pins
24 thru
On. If
IC9
pins
there
by
substitution.
24 thru
RAM
Expansion
Display
substitution.
Generator
by substitution.
pin
7 of SAM IC
pin
at
RF Modulator by substitution.
35 of IC9,
31
of IC9
are no
31 of
IC9
ICs (IC14
RAM IC
characters.
7 of IC22,
(B) If the keyboard
for
pulses at pin
pulses are
(C) If
pulses are
IC (IC7)
(D) A group
keyboard
tions.
CASSETTE
©
IC
(A)
Cassette
Check
of
run,
while saving
by substitution.
Also
Relay
Connector
check for
gram from
the time,
(B) If
Relay RY1
substitution.
(C)
Programs
and
DAC IC
(D) Programs
IC2 and
SALT IC
connector checks
11
missing, check
present
of keys
Connector
check
motor will not
of Decoder
at pin 11 of IC11,
do not
(CN2) for
IC7
by substitution.
run or
RY1 contacts
JK4. If the
continuity
a
program on
tape. If the cassette
check
for
checks
cannot
(IC3)
cannot
(IC1)
cassette
a short (relay
good, check
be saved
by substitution.
be
loaded from
by substitution.
IC11
by substitution.
work.
runs
between
between
tape or
motor
contacts
on tape,
good,
check
IC (IC11).
check
PIAJ
Check the
good connec-
all the time.
pins
and
1
motor
will not
pins
1 and
loading
PIA
tape.
runs
stuck).
IC (IC2)
Check
Check
a pro-
all of
IC2
If
3
3
by
III
PRELIMINARY
SERVICE
CHECKS
(Continued)
@@@(7D)
CLOCK
(4C)
TC1
^-^
PINS
34
AMD 35
PULSES
!C3
PSMS 24
THRU 31
PULSES
PULSES
1
PIN
11
ICT1
PIN
7
)(2A)
579MHz
lp\
C22
J
(4A)
2A)
33
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3D
IV
PRELIMINARY
SERVICE
CHECKS
(Continued)
@@@(7D)
CLOCK
(4C)
TC1
^-^
PINS
34
AMD 35
PULSES
!C3
PSMS 24
THRU 31
PULSES
PULSES
1
PIN
11
ICT1
PIN
7
)(2A)
579MHz
lp\
C22
J
(4A)
2A)
33
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W
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m
3D
IV
JOYSTICKS
(?)
(A) Joystick does
(B)
PRELIMINARY
not work,
following program:
10 FORX
20 Y
30 NEXT X: GOTO
=
=
JQYSTK(X)
0TO3
10
While the program is
pins
and
19
ing, check IC7 by substitution.
if
pulses
of PIA IC
39
are present at pins 19 and
check for pulses at
the pulses are missing at
IC11 by
substitution.
Type
running check
(IC7).
pin
11 of
pin
SERVICE CHECKS
SERVICE
in
and run the
for pulses at
If pulses are miss-
of IC7,
Decoder
39
IC <IC1
11 of IC11,
1).
check
If
(9_)
(Continued)
CHECKS
If pulses are present at
(C)
pulses
pulses
(D) If pulses are
check
Joystick buttons
(E)
joystick
joystick Connectors JK1 and JK2 for good con-
nections.
(F) If the joystick buttons and connectors are good,
check PIA
__
pins
at
are
4
missing,
present
DAC IC (IC3) by
buttons for
IC (IC7) by
SERIAL I/O PORT
Serial port
(A)
SALT IC (IC1)
not work. Check PIA IC (IC2) and
does
by
pin
thru
do
substitution.
11 of IC11, check for
of
9
PIA IC (IC2).
check
IC2 by
at pins 4 thru 9 of IC2,
substitution.
not work. Check the
continuity.
substitution.
substitution.
If the
Also check
POWER
The
with no
Computer
UP
Computer will come up
cartridge
come
will
RESET
The Computer
located on
(SW2)
PROGRAMS
BASIC
Basic
A
RUN
ing
stopped
be
CABINET
Remove sfx
Computer
MAIN BOARD
will be
program in the
and then pressing
pressing the
by
REMOVAL
Phillips screws
right side
REMOVAL
in the slot.
running the
up
Reset
right rear of
Computer
and remove
up
GENERAL
in Basic
If
cartridge
a
pressing
by
cabinet.
RAM
ENTER key.
the
BREAK key
from
OPERATING
mode when
program
can
or the
turned On
installed, the
is
in the cartridge.
the Reset
started by
be
program can
The
Reset button.
DISASSEMBLY
cabinet bottom.
cover.
button
typ-
Turn
INSTRUCTIONS
CASSETTE
Connect
the Computer using the cable furnished with the Computer.
Plug the black plug on the cable into the Earphone
large
into
To
load
mode with the
CLOAD and
pear
the program.
ter
F
after the
save
To
Record mode.
The
gram has
OPERATION
cassette recorder
a
gray plug into the Auxiliary jack and the small gray plug
the Remote On/Off
program from
a
volume turned about half
then
press the Return key. The letter
on the Monitor screen while the Computer searches for
the
will
When
appear on the screen and the word
program has been loaded.
a program to cassette, put the Recorder in the
Type CSAVE and
word
will appear on the Monitor screen after
OK
been saved and the Recorder will shut Off.
to the Cassette Socket
on the Recorder.
jack
cassette, put
Computer
the Recorder in Play
finds the
then
press the Return key.
(JK4)
jack,
way up.
program, the let-
OK
Type
will ap-
S
will appear
the pro-
on
the
INSTRUCTIONS
board. Remove six
cabinet
of Main board
tom
board.
POWER
and
base
TRANSFORMER REMOVAL
Phillips screws
remove board.
removing 17 clips that attach it to
by
holding Main
Remove shield from bot-
board
to
the
Carefully
remove
disconnect
Keyboard.
keyboard
Unplug
cable from
Power
Transformer
MISCELLANEOUS
CLOCK
Connect
(IC22).
3.579545MHz.
RF
Connect
VI
ADJUST
input
the
the
Adjust
MODULATOR
Computer
of
a
Clock
to a
frequency
counter to
Trimmer (TC1)
Monitor.
TV
for
Set
Main board
from Main
pin
of SAM
7
frequency
a
and
the TV
and
the
Unplug Power
Phillips screws
Transformer
holding
ADJUSTMENTS
Channel Select
the following program:
IC
of
10 SOUND
Adjust the Channel 4 Coil for best
just the sound coil for best sound
the TV
and the
Adjust the Channel 3 Trimmer
Switch
200,200:
Channel
from Main board. Remove two
Power Transformer to cabinet base.
to Channel 4. Type in and run
(SW3)
GOTO10
Select
t
picture and sound.
with minimum noise. Set
Switch SW3 to
for best picture and sound.
Channel
Ad-
3.
PRELIMINARY
SERVICE CHECKS
(Continued)
CASSETTE
POWER
RESET
(SA)e
SOUND
RF
MODULATOR
(3A)(4B)
CHANNEL 4
<S>
CHANNEL 3
120MC
R2
OB)
s.ov
source
/
IC1
(IS)
©
6a)
SALT
o
PULSES
IC7
PI
A
C6A (6D
@
©
PULSES
@©@
(g)
4
7
8
^9
IC2
P1A
KEYBOARD
3
>
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33
INTERCONNECTING
DIAGRAM
II
INTERCONNECTING
DIAGRAM
VIS
PRELIMINARY
ENVIRONMENT
SERVICE CHECKS
PREVENTATIVE
(Continued)
MAINTENANCE
Computers perform
dust and smoke particles.
as much
around the
Monitor, Printer, or
as
Computer.
best in
commercial
Do
other
ELECTRICAL POWER
Variations in
an AC receptacle
devices.
may
be
the line
that
A power-surge
needed
cure
to
voltage can
is
KEYBOARD
Liquids spilled into
Computer
power
disassemble the
water and
cleaner
DISK
Clean the
let it
and
DRIVES
read/write
Use only an
Handle
carefully
Drives
can knock the disk head
an old disk
in slot and
the
plug from AC
Keyboard
dry.
Use a
lint-free
wipers on accessible
heads of the Disk
approved head cleaning
preserve
to
close door during
clean,
a
cool
Even though
Computers
not
are affected,
block cabinet
power devices.
power
a
protector,
affect the
line not
power-line
Do
on
the problem.
Keyboard can ruin
power outlet.
and carefully
cotton
swab to clean
kit.
proper disk
out of alignment.
area that
home
is
Computers
it is better
vents
of
Computer. Try
used
by appliances
conditioner,
not switch
it. Immediately
Then, if circuitry
rinse
the Keyboard printed
between the keys.
connectors and
Drives
about once
head alignment.
transport.
If the disk drive
below
80 degrees
are not
any
to maintain
of the
Computer
to avoid
or other
or
non-interruptable power
power On and
after a spill occurs,
or
contacts.
month
a
A
sudden bump or jolt
Fahrenheit and free of
affected
by cigarette smoke
smoke-free
a
system; Computer,
these fluctuations by using
heavy current demand
supply
Off
frequently.
disconnect
contacts are
circuit
Use
a
or after
must
contaminated,
board with distilled
non-abrasive
100 hours usage.
to
contact
the
be transported,
Disk
place
area
the
Store
disks in their
handling
precautions usually found
PRINTERS
Carefully vacuum
cleaner.
blanket.
a
STATIC
Static
anti-static mats,
vironment.
not
Do
This can
ELECTRICITY
electricity discharge
MONITOR
an isolation
Use
some Monitors
the Monitor
when
preserve
pattern
the
should never
is being
glare-reduction
protective covers and
the Printer
oil the machine.
regularly.
cause components
can affect
sprays, tools
transformer
and materials,
with any
use a HOT chassis
left
be
changed periodically.
feature.
on the
Wipe surface
The oil will
to overheat
the
Monitor
(chassis
on for long
never
touch the disk
back of disk
collect abrasive
protective
areas clean
grit and dust.
and fail.
Computer. In order
and maintain
that
does
to
good humidity in
not
come
connected to one side
periods of
time at high brightness
Use caution when cleaning
surface. Observe
covers.
using
light
a
The dust will
minimize
as
of the AC line). The
the
possibility,
the
Computer en-
part of
the system
anti-glare screens,
the disk
all-purpose
act
as
use
since
face of
level except
to
Vtll
SAM
CM
cc
HI
i-
=5
CO
a.
CO
2
CO
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CM
cc
o CO
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^
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u
111
<
a
X
o
(/)
s
o
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<
CC
in
T"
o
o
PRELIMINARY
Block Diagram
Disassembly
General Operating
GridTrace
IC Pinouts and
Line
Logic Chart
Miscellaneous
S
Location
Definitions
COMPUTERFACTS"
SERVICE
ENCLOSED
Instructions
Instructions
Guide
Terminal Guides
Adjustments
CHECKS
Page
24
25
25
3,22
17
15,16
25
INDEX
7
•nataie
-
:
^-'-;*;V-;^
SAFETY
Parts
List
Photos
Safety
Precautions
Schematic
Schematic
Test
Troubleshooting
Notes
Equipment
RADIO
SHACK COLOR
MODELS
mm
PRECAUTIONS
See
page 18.
26-3134,
11 thru
5,
6,19,20
2,4,21
8,9,10
COMPUTER 2
26-3136
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30
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14
18
23
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33
NS
SAMS
The listing of any available replacement
constitute in
Howard W. Sams
replacement part. The numbers of these parts have been compiled
from information furnished to Howard W. Sams
manufacturers
im
recommendation, warranty or guaranty
any case a
Inc.,
& Co.,
of
as
the particular type of replacement
Howard
4300 West 62nd Street, P.O.
to the quality and suitability of such
W.
part herein
& Co..
Sams
does
inc., by the
listed.
part
& Co.
not
by
Box 7092,
Reproduction or
content,
respect to the
© 1986 Howard W. Sams & Co.
4300 West 62nd
Printed in U.S. of America.
Indianapolis,
without express
use,
in any
manner,
use of
prohibited. No patent liability is assumed
is
the information contained herein.
Street, P.O. Sox 7092, Indianapolis, Indiana46206 USA.
Indiana 46206 U.S.A.
permission,
86CC14969 DATE
editorial or
of
pictorial
with
4-86
A
PHOTOFACT STANDARD
NOTATION
SCHEMATIC
w.THHEBffiQEBl
©
Howard W. Sams
&
Co.,
Inc.
1886
RADIO
SHACK
COLOR
COMPUTER
MODELS
26-3134, 26-3136
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