Sams Commodore Plus/4 User manual

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PRELIMINARY SERVICE CHECKS
This data provides the user with a time saving service tool
which is designed for quick isolation and repair of Computer
malfunctions .
Check all
interconnecting cables for good connection and
correct hookup before making service checks .
Replacement
or repair of the Power Supply, Main Boar d, or
Keyboard or connectors may be necessary after the mal-
function has been isolated.
GENERAL OPERATING INSTRUCTIONS
PO WER UP
The Computer will come on ready to program in Com·
modore Basic when turned On.
For instructions on loading
and saving programs see "Cassette or Disk Operationn sec-
tion of the General Operating Instructions . To run a pro-
gram
when loaded, type RUN and press the RETURN key.
To
stop a program in progress, press the RUN/STOP key. A
program can
also be stopped by pressing RESET button on
the ri
ght side of the Computer but the program will also be
lost.
MONITOR PROGRAM
The Computer has a built·in Monitor program to enable the
user
to program with machine language. To go from Basic
to Monitor, hold down the RUN/STOP key and press the
RESET key. The word MONITOR will appear at the top left
of the display screen. To go back to Basic from Monitor,
type X and press the RETURN key.
CASSETTE OPE RAT IO N
Plug a Datassette Recorder into Con nector CN3 at the rear
of the Computer. Note: A standard tape recorder will n ot
work on the Commodo re Plus/4. To load a program, ty pe
LOAD, press the RETURN key and fol
low the in structions
displayed on the Monitor screen. To save a program, type
SAVE, press the RETURN key and
follow the instructions
displayed on the screen.
DISK OP ER ATION
Connect Disk Drive unit to the Serial 1/0 Connector (CN2)
located
at the rear of the Computer. Carefully insert the
diskette so that the label on the diskette is facing up and
the
notch on the diskette is on the left side. Once th e
diskette has been inserted, close the protective gate by
pushing down on the gate lever. To load a program fr om the
diskette , type LOAD "PR OG RAM NAME", 8 and press t he
RETURN key. To save a program, type SAVE "PROGRAM
NAME", 8 and press the
RET UR N key.
NOTE: Number 8 is the Device number the D isk Drive is nor·
mally set up for. The device
number can be any n umber
from 8 to 11 depending on how the device number jumpers
are connected in the Disk Drive.
Datasette
is a trademark of Commodore Business Machines, Inc.
DISASSEMBLY INSTRUCTIONS
CA BI NET TOP RE MOVAL
Remove five screws from cabinet bottom holding keyboard
assembly and cabinet top. Carefully
lift cabinet top from
unit and disconnect keyboard ribbon wire from main board.
KEY BO A RD REMOVAL
Remove eight screws holding keyboard assembly to
cabinet top. Lift Keyboard from cabinet top.
CPU BOA RD RE MOVAL
Remove five sc rews holding C PU board to cabinet b ottom.
Lift CPU board from cabinet.
Howard W. Sams & Co., Inc.
4300 West 62nd Street . P.O. Box 7092. Indi anap olis. Indiana 46206 U.S.A.
Th. listing 01 any o\!oUobl. replac.ment po,t nere in doel not R.prod ... cIlOfl or ule. wllho ... 1 •• pr.1I pe,mlilion. 01 ediloriol or pictorIa l
cOnslllut. in any
cal. a flKOmmendoli on . warranty or guaranty by conl.nl . I" any mon".r . 11 pr ohibited . No pol."ll/ oblllty I, o .. ... ~ wilh
Howard W. Soml &
Co .. In c .• 01 10 ,h. quality and lu ilobility 01 luch r.lpeel to 11'1. u •• of In. Informollon conlol ned ....r .i".
replac.menl porI. Th. numbers 01 Ih ... po,1I h"". be.n compiled Cl 1965 Howard W. Slm. & CO .• 1m:: .
Irom I
"Iormollon !u", ' shed 10 Howo,d W. Soml & Co .. Inc .. by 'h. 4300 W.s I 62nd SI,_I . P.O. 80. 7092. IndionopoUs. Indiana -'6206 U.S .A.
mon
... loclu, ... 01 Ih. po,l lc ... lor type 01 replac.m.nt porlli.ted . Prlnled In U.S . 01 America. 84 CC1 49 31 DATE 1.85

PRELIMINARY SERVICE CHECKS (Continued)
SERVICE CHECKS
SEE INTERCONNECTING DIAGRAM, PLACEMENT CHART, AND PHOTOS TO MATCH
THE NUMBER IN THE CIRCLES WITH THOSE IN THE FOLLOWING DATA FOR SERVICE
CHECKS
TO BE PERFORMED.
CD RF MODULATOR (SNOWY SCREENI
(B) If the Mi croprocessor is working and the Com·
puter does not come up, check Kernal IC (U24)
and PLA IC (U19) by
substitution. (A) Turn Computer On a nd check if the Power In-
dicator LED is lit. If Indicator LED is not lit, see
"Power Supply" section of the Preliminary Service
Checks.
(8) Make certain the TV and Computer Channel
SelectorSwitchesare on the same channel L (3) or
H (4).
(C) Make certain the Antenna Switch is In Computer
position.
( 0) Check for open or intermi ttent connect i ons or an
improp er h ook up at both the Monitor and Com·
puter.
(E)
Check lor 5V at end 01 Coil L4, lor .9V at pin 1 01
Connector eN7 and for 1.6V at pins 4 and 6 of
Connector eN7.
(F) To help Isolate problem, connect the Video Input
of the Monitor to the Video Output Connector
eN7. If video appears, replace RF Modulator
(M1). If the video does not appear when Video In-
put of Monitor is used, the problem is probably
not the RF Modulator. See "Main Board (Process·
ing)" section
of th e Pr e limin ary Service Checks.
® POWER SUPPLY
(A) Conne
ct the P ower S upp ly to 120V AC. Discon-
nect P ower Conn ector (CN 1). Check f or SV DC
between pins 1and 2
of Connector CN1 . Check for
10 .6V AC between pins 3and 4 of Connector CN1.
(6) Check AC Fuse
(Fl) .
(C) If the AC Fuse ( Fl ) is open, check lor a shorted
Diode (CR 1).
(D) Connect the Power Supply
to the Compute r, press
P
ower Switch (SW1) On and check f or 13.8V at
the
positive (+ ) end of E lectrolytic C7 .
0) MAIN BOARD (PROCESSING)
II
(A) If the power supply Is normal but the Co mpute r
does notcome up when powered, check fora
clock
waveform at pin 1 of C PU IC (U 2) and also check
IC U2 by substitution .
(C) If Computer comes up but not in Basic Ready
mode , che ck Basic ROM IC (U 23) by substitu-
tion .
(D)
If the Computer does not come up and the
Monitor screen remains black, check for clock
waveforms at pins 12 and 14 of TED IC (U1) .
(E)
If special programs activated by pressing the
functio n switches do not operate, check Function
Low IC (U25) and Function Hi IC (U26) by
s
ubstitution .
(
F) Disk Drive or Printer does not function properly.
Check
for open or i ntermittent connections at
Connector CN2.
(G) Vi deo Output Connecto r (CN7) does not function ,
check TEO IC
(U1) by substituti on. If IC U1 is
good, check the RF modulator (M1).
(H)
Joystick Connectors (CN5 and CN6), Keyboard
Connector (CNS) or Expansion Connector (CN4)
do not fun ction, check the CPU IC (U2) by
substitu ti on .
(K)
No sound , check Audio Amp Transist or ( 03 ) by
substitution.
(L) Sound only miss ing when game cartridge is us}d ,
check Electrolytics C17 and C1S .
o KEYBOARD
(A)
If any or all of the keys function abnormally,
check
Connector CNS and check the keyboard by
substitution .
(8)
If the functio n keys do not function properly,
check Function Low IC (U25) and F uncti on Hi Ie
(U26) by substitution .
CD CASSETTE OPERATION
(A)
If cassette motor does not run, check voltages at
Motor Drive Transistor (04)and also che ck Zener
Diode (CR2) by
sub s tituti on.
(B)
If the cass elle motor s till doe s not run, check IC
(U7) by s ubstitut ion.

PRELIMINARY SERVICE CHECKS (Continued)
H<WJTOR
@
ANTENNA
TV
CHMtIEL
SELECTOR
SWITCH
INTERCONNECTING DIAGRAM
VI
VIDEO IN
@
11
111
~
AF I1OOUl.A TOR
@
FmCT2
WVIDEO
® LEVEL
...... 1
••••• 5
® El=+
+~
041.010 AHP
i©sv
CN8
YI
'4.318181ftr
LED
POIIER
..I It«)JCATOR
If@
.9V
1.6V @
®
EXPAHSION
OSCILLATOR
Q2
U23
BASIC
(ROO
®
21
71
®
40
3
D D
2 I
CH3
FRONT vIEW
13.8V +
@)
U2
@®
21
71
U24
@ KEYBOARD
@
PRELIMINARY SERVICE CHECKS (Continued)
C7
z;oosr
sv
@>®
IO.SVAC
@)
RESET
SIi2
POIIER SI.f'Pl.Y
@)
PI. 1
POlARIZED
120VAC
~
INTERCONNECTING DIAGRAM
III

PRELIMINARY SERVICE CHECKS (Continued)
@)@@@
~
f
VIDEO OUTPUT
14 . 31818MHz
C10
@ RF OUTPUT
®{ RF
~ MODULATOR
® M1
{
CHANNEL
f1B\ SELECTOR
~ SWITCH
@5V
®{:::----
MAIN BOARD
IV
@
~ AUDIO
® AMP
CN8
PIN 1
KEYBOARD
@@
CN7
" ®
®®
@ ® ® A
r
EXPANSION PIN 1 PIN 1
CN4
U25 U26
PRELIMINARY SERVICE CHECKS (Continued)
® @® 3F
@@r
~OTOR' ® ®
SERIAL ®
@)
DRIVE PIN 1
PIN 1
PIN 1 1/0
U1
Q4
U19
U2 CN2
CR1
MAIN "BOARD
V
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SEE PAGE 3

PRELIMINARY SERVICE CHECKS (Continued)
MISCELLANEOUS ADJUSTMENTS
Alignment Tools GC ELECTRONICS
Tl ........ . .
.............. 5000,5009,8276
CRYSTAL OSCILLATOR ADJUSTMENT
Connect a frequency counter to the base of Oscillato r Tran-
sistor (01). Adjust Trimmer Capacitor (elO) for a frequency
of 14.31818MHz.
RF FREQUENCY
Connect the Computer to a TV and set the TV and Computer
Channel Selector Switches to the same channel L(3) or H
(4). Adj ust T1 tor the best picture with MINIMUM noise from
the TV speaker.
VIDEO LEVEL
Connect the Computer to a TV and set the TV and Computer
Channel Selecto r Switc hes to the same channel L (3) or H
(4) . Adjust the Video Level Trimmer Capacitor (C T 2) for the
best
picture on the M onitor .
TEST EQUIPMENT AND TOOLS
TEST EQUIPMENT
Digital Volt/Ohm Meter
Logic Probe
Monito r with Audio
Frequency Counter
ITEM PART NO.
C7 900101-33
Cl0 251029·01
C17 900100·25
C18 900100·25
CRl
251026·01
CR2 900927-01
Fl
903556·18
L4 90 11 52-01
LED
Ml 251311·01
TOOLS
Phillips Screwdriver
Low Voltage Soldering Iron
Desoldering Tool
Alig nment T oo l (GC ELECTRONICS 5000, 5009, 8276)
Small Screwdriver
REPLACEMENT PARTS
DESCRIPTION
El eclrolylic , 2200~F 16V
Trimmer , Oscillator, 40pF
Electroly
tic 10 JL F 16V
Electrolytic 10JLF 16V
Diode, Bridge Rectifier, 2B4-E
Diode, Zener, 83C6V8 (6
08V)
Fuse,
AC 1.5A @ 250V
Fast
Acting
Coil
LED, Power
Indicator
RF Modulator , with Channel
Selector Sw itc h (H/L) and
Video Level
Trimm er (C T2)
ITEM
Ql
Q3
Q4
SWl
Ul
U2
U7
U1 9
U23
U24
U25
U
26
PART NO.
902653·01
251587-01
901522·06
251641·02
318006·01(1)
318005·04(1)
317053·01(1)
317054·01
(1)
(1) Number on Unit
DESCRIPTION
Transistor, Oscillato r
2SC945
Trans
istor, Audio Amp 2SC945
Transistor , Motor Drive T1P29
Switch , Power
IC, TED, MOS8360Rl
IC, CPU, MOS8501
Rl
I C, SN7406N
I
C, PLA, 7700 ·0 1D
IC, BASIC ROM, 26011B·575
IC, Kernal, 26011 C·699
IC,
Functi on Low, 260110-717
IC, Fun
ction HI, 26011D·718
Power
Supply Unit
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VII

PRELIMINARY SERVICE CHECKS (Continued)
SAFETY PRECAUTIONS
1. Use an Isolation transformer for servicing.
2. Maintain AC line voltage at rated input.
3. Remove power from the Computer before servicing or installing electrostatically sensitive devices. Examples of typical
ES devices are integrated circuits and semiconductor "chip" components.
4. Use extreme caution when handling the printed circuit boards. Some semiconductor devices can be damaged easily by
static electricity. Drain off any electrostatic charge on your body by touching a known earth ground. Wear a commercial·
ly ava ilable discharging wrist strap device. This should be removed pri or to applying power to the unit under test.
5. Use a grounded·tlp, low voltage soldering iron.
6. Use an isola tion (times 10) probe on scope.
7. Do not remove or install boards, floppy disk drives, printers, or other peripherals with power On.
B. Do
not use freon·propelled sprays. These can generate electrical charges sufficient to damage semiconductor devices.
9. The Computer cabinet is equipped with ve nts to prevent heat build·up. Never block, cover, or obstruct these vents.
1
0. Instructions should be given, especially to children, that objects should not be dropped or pushed into the vents of the
cabinet. This could cause shock or equipment damage.
11. Never expose the Computer to water. If exposed to water, turn the unit Off . Do not place the Computer near possible
water sources.
12. Never leave the Computer unattended or plugged into the AC outlet for long periods of time. Remove AC plug from AC
outlet
du ring lightning storms.
1
3. Never use liquids or aerosols directly on the Computer. Spray on cloth and then apply to the Computer cabinet. Make
sure the
Computer is disconnected from the power line.
VIII

COMMODORE
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MODEL PLUS/4
SAFETY PRECAUTIONS PRELIMINARY SERVICE CHECKS
See page 21 . ENCLOSED
INDEX
Block Diagram ................ . .. .. .
Disassembly Ins tructi ons . ..... .. ... .
General Operating Instructions ..
GridTrace L ocatio n Guide
Main Board . . . .. ... .. . .... .
Ie Pin outs & Terminal Guides
Logic Chart
Main Board
Miscellaneous Adjustments.
Page
.21
. .20
.... .20
..7
.. 8
.13 ,1 4
.
... 14
Par ts · List
Photos
Main Board
Safety Pre cautions
Schematics
Pag e
...... 10,11,12
.
....... .4,5,6,15,16,17
. •• . . . . . .
... 21
Main B oard. . .2,3,18
Notes.. . . ........• .. ............. 19
Troubleshooting ..... . ... . . . • • • . •... . .... .. 9
S~N~ ,.
Howard W. Sams & Co., Inc.
4300 West 62nd Street , P.O. Box 7092, Indionapolis , Indiana 46206 U.S.A.
Th. li n i ng of any availab le r.plac.m.nt port her.in do., not
(onstitut. In Iln" co •• Il re<:ommendlltl on . wllTr ll nty or gUCl,onty by
Howord W. Somt & Co" I n< " Ot to th. quolity and lu ilobllity o llu ch
r.plac.men t pelrl. Th. numbeu D lthet.. porh hove be.n c ompiled
from informDti on furni lhed 10 H ow o,d W. Soml & Co.• In< " by th.
mllnuiodu' .... 01 th. porllculllr type of ,.plac .... ent pCIM lil t ed .
R.produclion or UI •. without .xp'." pe rml .. lon. of edlt o, lo! or p<ctoriol
conl .nt . in Il"y mo nn.r . II prohlblled . No po len t 1I0blllty II OIiUmed with
r.' pect 10 the UI. of the Inlorrnollon cOIl toln.ci her.in .
C! I~ HOWard W. Sam, " CO " In<: .
.300 WMt 62nd Sir_ I. P.O. Bo x 7092. Indl_poU •. Indlono 046206 U.S.A.
Printed In U.S . 01 Amerk ll . 84CC14931 DATE 1.85
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SEE PINOUTS, TERMINAL
GUIDES AND SCHEMATIC
NOTES PAGES 8.19
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SEE PINOUTS, TERMINAL
GUIDES AND SCHEMATIC
NOTES PAGES B.19
14t RF HOOULA TOR
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SCHEMATIC CIRCUITRACE =
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A PHOTOfACT STANDARD NOTATION SCHEMATIC
WITH Iii·AiI"·'·A-
© Howard W. Sam. & Co., Inc. 1985
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7 8 9 10 11 12
13 14 15
7 8 9 10
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15
16 17 18
19
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MAIN BOARD GridTrace LOCATION GUIDE
CI
F-26
CR20 0-5 J9 C-23
C2
E- 27
F1
E- 23
L1
C- 27
C3
C-26
FB2 C -3
L2
C- 26
C4
0- 26
FB3 C-2
L3 H-B
C5
0- 26
FB4 C-3
L4
1-4
C6
0-25
FB5 C-2
PI
A-21
C7
C- 21
FB6 B -3
01 G-7
CB
C -1 B
FB7 A -3
02
G-B
C9 C
-I B
FBB C-3
03
M-2
C10
G-6
FB9 B- 22
04
C- 17
CII
G-6
FB10 A- 24
R1
H-7
CI2 H-B
FBI I B- 24
R2
H-7
C13
1- B
FB12 B- 23
R3 H-B
CI4
G-B
FBD B- 23
R4
H-7
CI5
G-9
FBI4 B- 22
R5
G-7
CI6 J- B
FB15 E-10
R6 F-7
CI7
J-2
FBI6
E -1 2
R7 G-7
CIB
K-2
FB17 E-10
R8 J-2
C19 M-2
FB18 F-16
R9 J-2
C20
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FBI9 1-1 2 RIO L-2
C2 1 1-3 F
B2 0 F-II R
11 L-2
C22
L-27
FB21
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R12
L-2
C23
E- 28
FB22
A- 26
R13 L-2
C24
t~ - 28
FB23
C- 24
R14
E-8
C25
H-28
FB24
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R15 F-6
C26
H-22
F825
C-25
R16
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C27
1- 22
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C28
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FB2B B-5 RI8 L-
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C30
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R23 F- 25
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Ie PINOUTS &TERMINAL GUIDES
U,
TOP VIE W
U2
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TOP VI EW
I 1 GROU ND
LINE DEFINITIONS
AO Thru A15 . . . . . . . . . . . . . .... ..... A ddr ess Line s
ADDR
Cl K . . .. ....... . .. ... . .. . ... . . ... Addres s Cl ock
AEC . . .Address Enable Control
ATN . . . .
.. . .. . . Att ention
BA .
BASIC
CSt
BRESET
Ct HIGH
Ct lOW
C2 HIGH
C2 lOW
....Bus Available
.
.... . .. . .. . . ...... .. .. Basic Chip Se lect
CAS .
... . . .. . • . ........ . .Column Address Strobe
CST
RD . . . . . . . . • . . . . . . Ca ss ette Read
CST MTR .
.. . .. . . . . . . • . . .. .. . ... Cass ett e M oto r
CST SENSE . . .
•. . . . .. . . Ca ss ette Se nsor
CST WRT . .
... . ......... ... ... .. ....... Casse tt e Wr ite
eso , CS1 . . . . . ... .. ... . .. ..... Chip Select Lines
00 Thru 07 . . . . . . . . . . . . . . . .Data Lines
EXT AUDIO . . . ....... External Aud io
FUNCTION HI .. . .Functi on High Line
FUNCTION LOW . .
... . ..... . . ... . . .. Function L ow Line
IRQ . . . . . . . . . . . .Interrupt Request
KO Thru K7 . . . . • . .. . . . . Ke yboa rd Matrix Line
KERN
KERNAl CSt .... ... . .. . ... ... Kernal Chip Select
KEYPORT CS . . . • . . .
.. . . .Key Pori Chip Sel ec l
MU X. . . . . . . . . . . . . . • .. . •• .Multiplex
R/W . . . . . . . . . . . . . . .Rea
dlW rite
RAS .........
..• . . .. Row Ad dr ess Strobe
RESET . . . . . . . . . . . . ... ..... ..... . ... R ese t
00 . ... . .. . . .. . .. ... . . . ... . . .. . . . . .Phase 0
02 . . . . . . . . . . . . . . . . . . . . . . . . . . ... Phase T wo
SN H06N
"""
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FliPIFLOP
lOP VIEW

TROUBLESHOOTING
POWER SUPPLY
Connect the Power Supply to 120V AG . Check for 5V be-
tween
pins 1 and 2 and for 10.6V AC between pins 3 and 4 of
(male) Connecto r eN 1. If voltages are missing , replace the
Power Supply. If voltages are normal, connect the P ower
Supply to (female) Connector eN1. Press the P ower Switch
(SW1 ) On and check for 5V at the positive (+ ) end of
Electrolytic Cl . Also, check for 13. 8V at the positive (+)
end of Electrolytic C7. If the 5V is missing , check Line Filter
(L1) and Switch SW1. If the 13.8V is missing at CAl Output ,
check DC Fuse (Fl ). If Fuse Fl is open, check lor a shorted
Diode CRl and also check Electrolytics C7 and ca.
MICROPROCESSOR (CPU) OPERATION
Check for 5V at pin 5 of the CPU Ie ( U2). See if the Micro·
processo r is functioning by check ing with a logic probe for
pul
ses on Address Lines, (pins 4 and 6 thru 22) and Data
Lines,
(p ins 31 thru 38) of IC U2. If the Microprocessor is n ot
functioning, turn the Computer Off and connect a logic
probe to pin 40 of IC U 2. Turn the Computer On and check
for a logic Low reading lasting about two seconds . After
two seco nds the reading will then change to logic H i, reset-
ting IC U2. If the logic readings are incorrect, troublesnoot
components associated with IC U7 and Timer IC UB.
Check for clock pulses on pin 14 of the TED IC (Ul). If the
pulses are missing , tr oubleshoot the Master Clock cir cuit
and check the frequency at the base of Oscillator Transistor
(01). Adjust Trimmer (C10) for a fr equency of 14.31818MHz
for (NTSC) or 17.7344MHz lor (PAL). If the frequency will not
adjust, check Crystal (Y1) by substitution and also check
voltages, waveforms and components associated with
Oscil l ator Tr ansi sto rs (01 and 02). If clock pulses are pres-
ent at pin 14 of IC Ul , check for clock pulses at pin 12 of IC
U1. If
the clock pulses are missing at pin 12 , check IC Ul by
s
ub stitutio n. If the cl ock pulses are present at pin 12 of IC
U1 , check for the clock pulses at pin 1 of IC U 2. If the clock
pulses are present at pin 1 of IC U2 and the CPU still does
not wo rk, check the IC U2 by su bstitution.
SOUND
If there is no sound , type and run the following progam:
10 VOL
8: SOUND 2, 222, 22: GOTO 10
Check for a square shape waveform at pin 33 of TED IC (Ul) ,
See
Figure 1. If the waveform is missing , check TED IC (U1)
by substitution. If the waveform is present , check the
vo lt ages and compo n ents associated with Audio Amp Tran-
sistor (03), El ectrolylic C20 and Ihe RF Modulalor (M1). II
the sound is on ly miss in g when using a game ca rtridge ,
check El ectrolytics C17 and C18 and associated com -
ponents.
Figure 1
32V
5ms
OV
VIDEO
Check for video
waveforms on pi ns 13 and 23 of the TED IC
(U 1) . If waveforms are missing, check IC Ul by subs tituti on.
If the waveforms are present, check for v id eo wavefor ms on
pins 6, 7 and 8 of the RF Modul ator (Ml). If waveforms are
missing , check Modulato r M1 by substitution. If the wave·
forms are present at Mod u lator M1 , check the Video Output
Connector CN7 for bad connectio n s.
COLOR
No color. Check for a colo r wavefo rm on pin 13 of TED IC
(U1).
If the waveform is missi n g, check Ie U1 by subs t itu·
tion. If colors are incorrect, check adju stmen t of
14.31818MHz Osc illator. See "Crystal Oscill ato r Adjust-
ment " section of Misce llaneous Adjustments .
KEYBOARD
Keyboard
does not work. Check the wavefor ms at pins 2
thru 9 of KernallC (U27). If any waveform is missing, ch eck
IC U27 by su bstitution. If the wavefor ms are normal , check
the Keyboard Connector CNS for goo d connections. If the
connections are normal, check TED IC ( U1 ) by substitution.
11 none of the function keys are operating, ch eck PLA Ie
(U 19 ) by substitution . If Funct ion Keys Fl /F4 or F1 / F5 are
not operating , check Function L ow Ie (U25) by substitution.
If Function Keys F3/ F6 or HELP/F7 are not ope rating, check
Function Hi IC (U26) by substitutio n. If any othe r key is er-
ratic
or does not operate, clean the switch contacts associ-
ated
with the erratic key with a contact cleaner.
CASSETIE OPERATION
Note: See
"Cassette Operation
n
section of the General
Operating Instru ctions for correct proced ures on loading
and saving programs wi th a Datassetle tape re co rder .
Check
Connector CN3 for good co nn ections. If a progra m
does not SAVE onto tape, check for pulses at pin 29 of CPU
IC (U2)
while attempting to save a program. If the pulses are
missing, check IC U2 by substitution. If pulses are present
at pin
29 of IC U2, check for pulses at pin 6 of IC U7. If the
pulses are missing at pin 6, check IC U7 by substit ut io n. If a
program
does not load fr om tape, check for pulses at pin 26
of IC U2 while attempting to load a prog ram. If pulses are
present at
pin 26, check pin 4 of Conne ctor CN3.
II the cassette motor does not run, check for a logic Low
reading at pin 3 and a logic Hi read in g at pin 4 of IC U7 while
attempting to save a program onto tape. If the logic reading
at
pin 3 of IC U7 is H i, check IC U7 by subst i tution. If the
logic reading is L ow at pins 3 and 4 of IC U7, ch eck IC U7,
Zener Diode (CR2),
Motor Orive Transist or (0 4) and Re sistor
R17 by substi tuti on. If th e rea dings at pins 3 and 4 of IC U7
are
normal , check for a logic L ow reading at pin 27 of IC U2
while attempting to save a program . If the logic rea din g at
pin 27 is Hi, check IC U2 by substitu tion.
Data
sette is a trademark of Commodo re B us iness Mach ines, Inc.
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9

~ PARTS LIST AND DESCRIPTION
When ordering part s, state Model, Part Number, and Description
SEMICONDUCTORS (Select replacement transistor for best results)
REPLACEMENT DATA
ITEM TYPE MFGR.
No . No. PART No. GENERAL MOTOROLA NEW·TONE PHILIPS WORKMAN ZENITH
ELECTRIC NTE
ECG
RCA
PART No. PART No. PART No. PART No. PART No. PART No. PART
No .
CA l 2B4 .E 25 1 026 - 01 r-tlA802 NTE5313
ECG53 13
SK3986/53B
251 026-02
25 1026- 03
CR2 83C6V8 900927- 0 1
GEZD - 6 .8 1N4736A NTE507 1A
ECG507 1A SK6V8/5071A
WE P1106/5 071 10
3-Z9 020
CR ll Thru
l N9 14 F 900850-16
GE -3 00
lN4935 NTEl77 ECGl77
SK9091/177
WEP 1 062/177
1 03- 131
CR20
lN41 4B 900850 - 01
GE -514 lN4935
NTE5 19
ECG519
SK3100/5 19 WEP925/519 1
03 - 13 1
01
Thru 2SC945 GE-2 12
WSA18" NTE85
ECGB5
SK3124Ai289A WEP736/1
23A" 121 -972"
03
2SC 1815 902693-01
GE-62 W'SA05"
NTE85
ECGB5
SK3 1 24Ai289A
WEP66/ 1 99 12 1- Z9065
Q4
TIP29
902653-01
GE -66A TIP298 NTE152
ECG152 SK3893/ 1 52
WEP745/ 1 52 12 1- 987 - 03
2SD880 902694-01
GE -66A
TI P4 1A NTE152 ECGI52
SK34 4 0/29 1 WEP745/152 12
1- 987-03
Ul ~S8360Rl
7360R7
251535-01
U2
~SB501Rl
,
7501Rl 251
536-01
U3
~S6551CBM
6551A 901895- 02
U4
~S8712
74LS08 90152
1- 03
74LS08 SN74LS08N NTE74LS08 ECG74LS08 SK74LS08
HE -4 43-780
U5
~S65298 251640- 03
U6
~SB7 1 3
74LS04
901521-02
74LS04 SN74LS04N NTE74L
S0 4 ECG74LS04
SK7 4L S0 4
HE -44 3-755
U7 SN74 06N
901522-06
GE-7406 NTE7406 ECG7406
SK7 4 06
HE-443- 698
U8
UA55 5TC 901523-01
GE I C-269
t-'C1455Pl
NTE955M
ECG955M SK3564/95 5M
WEP2119/955M 22 1- Z9042
U9,1 0 74LS257A
90 1 521-57
74LS257 SN74LS25 7
AN
NTE74LS257
ECG74LS25 7 SK74LS257
HE-443-802
Ull Thru HM4B64P-3
U18 4164- 2
901505-01 NTE41 64

~
~
PARTS LIST AND DESCRIPTION (Continued)
When ord eri ng parts, state Model, Part Number, and Description
SEMICONDUCTORS (Select replacement transistor for best results)(cont)
REPLACEMENT DATA
ITEM TYPE MFGR.
No.
No . PART
No . GENERAL
ELECTRIC
PART No.
UI 9
7700-0 10 25 1 64 1- 02
U20 74LSI 39 901 52 1- 18 74
LS 1 39
U2 1 SN74LS
175N
90152 1 -34
74 LS I75
U22 T74LS278 I 901 52 1- 22 74LS27
U23
260 11 8- 575
31 8006-0 I
( 1)
231288 31
8006-0 1
U24 26
011 C- 699 31 6005 - 04
(1)
231288 3 180
05 - 01
31
800 4- 01
(2)
U 25 260110-71 7 31
705 3- 0 1
I 1)
231
28
2364
U26 260
11 0- 718 3 17 05 4- 01
(1)
231
28
2364
U27
M:lS65298 25 164 0-03
# For SAFE TY u se o nl y e qui va le nt r ep l aceme nt pa rt.
* Lead co nf igura ti on may va ry fr om o ri g in a l.
(1) Nu mbe r on uni t .
(2) Used In Unit ed Kingdom and Ge rm any.
WIRING DATA
PH ILIPS
NEW·TONE
MOTOROLA NTE E
CG
PART N o.
PART No. PART No.
SN74LS I39N NTE74LS 139
ECG74LS I39
SN74 LS1 75N NTE74 LS175 ECG74 LS 17 5
SN74LS27N NTE74LS27
ECG74LS27
840 1 or 842 1 (Si ngle-Conduct or )
8208 (T wo-Co nductor )
RCA
PART
No .
SK74LS 139
SK74 LS175
SK74LS27
Shi e l ded Hoo k-up Wi re •.. • ••• • •• • •••••.•.. Use BE LDEN No .
Ge nera l- use Un sh ie l ded Hook -up W ir e .• •••• Use BE L DE N No.
300-D
hm Inp ut Lead . ••• ........•.••.....•. Use BE L DE N No .
8529 (So l id ) Ava i lable In 13 Co lors
8522 (S
tr anded ) Ava i l ab le In 13 Co l ors
6225
75- 0 hm Input Lead • •.•••• •• •• ••••...••••• Use BE L DEN N o.
824 1
~/snld 13COW
3HOCOWWOO
WORKMAN ZENITH
PART No. PART No.
HE-443-
752
HE -44 3- 800