Commodore Plus 4 User manual

SERVICE MANUAL
MODEL PLUS 4 COMPUTER
OCT. 1984 PN-314001-04
Commodore Business Machines, Inc.
1200 Wilson Drive, West Chester, Pennsylvania 19380 U.S.A.
Commodore makes no expressed or implied war-
ranties with regard to the information contained
herein. The information is made available solely on
an as is basis, and the entire risk as to quality and
accuracy is with the user. Commodore shall not be
liable for any consequential or incidental damages
in connection with the use of the information con-
tained herein. The listing of any available replace-
ment part herein does not constitute in any case
a recommendation, warranty or guaranty as to
quality or suitability of such replacement part.
Reproduction or use without expressed permission,
of editorial or pictorial content, in any matter is
prohibited.
This manual contains copyrighted and proprietary information. No part
of this publication may be reproduced, stored in a retrieval system, or
transmitted in any form or by any means, electronic, mechanical,
photocopying, recording or otherwise, without the prior written permis-
sion of Commodore Electronics Limited.
Copyright
© 1984 by Commodore Electronics Limited.
All rights reserved.

CONTENTS
RF MODULATOR 251844 LAYOUT .
251844 SCHEMATIC
• • ••• • • • • • ••• •• • • • • • • • • • • • • ••••• • • • • •••••• • • •••• • • ••••• • • • • • • • • ••••
Page
1
2
3
3
4
5
7
7
9
11
11
12
12
Title
SPECIFICA TIONS
• • • • • • • • • ••• • • • • • • ••••••• •
•••••• • • • • • • • ••• •••• • • ••• • • • • • •••••• ••••••• • • • • • • • • • • • • ••••• • •••• • • • • • • •
OVERVIEW .••• • ••• • • • • ••
• ••• • • • • • • • • • • • •••• •• •••• • • ••• •• •••• • • •
PRODUCT PARTS LIST .
CASEWORK IDENTIFICATION
• • ••• • • • • • • • • • • • • • •••••• • ••• • • • • •••• •• • • •••••••••••• • • •••••••• • • • • • • • • • • • • • • • • • • •
PCB LAYOUT .
PCB PARTS LIST
• • • • • • • • • • • • • • • • • • ••• ••••• • ••••• • •••• •••••••••• ••• •••••• • • • • • • • • •••
• • •••••• • • • • • • • • • • •• • • • • • • • • • • • •
PCB SCHEMATIC DIAGRAMS
•••
• • • • • • ••• ••••••• • • • ••••• • • • • • • ••••••• • • • • •••••• •• •••••• • • • • ••••
• • •••• •• • • • • • • •
KEYBOARD MATRIX .
I.C. PINOUTS FOR UNCOMMON CHIPS •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
RF MODULATOR 251311 LAYOUT ..
251311 SCHEMATIC .
iii/iv

PLUS 4 PRODUCT SPECIFICATION
MEMORY
64K RAM. 60K RAM User accessible for BASIC programs.
ROM
32K ROM Standard (includes operating system and BASIC interpreter) with 32K additional ROM con-
taining the built-in productivity software.
MICROPROCESSOR
7501 Microprocessor - .89 or 1.76 MHz clock.
DISPLAY
40 Columns x 25 lines of text.
COLORS
128 Colors (16 colors; 8 luminance levels).
CHARACTERS
Upper
& lower case letters, numerals and symbols. Reverse and flashing charachters. All PET graphic
characters.
DISPLAY MODES
Text characters. High resolution graphics. Split screen text/high resolution graphics. Multicolor graphics.
RESOLUTION
320 x 200 Pixels
SOUND
2 Tone generators or 1 Tone and 1 white noise generator.
VOLUME
8 Volume levels
KEYBOARD
Full size typewriter style design
KEYS
67 Keys total. 4 Cursor control keys. 4 Programmed (reprogrammable) function keys (up to 8 user
defined functions possible). Color control keys. HELPkey. Upper and lower case character set. Graphics
character set.
INPUTS/OUTPUTS
PLUS/4 MODEM (User) port. Serial port. ROM cartridge and parallel disk drive port. 2 Joystick ports.
C1531 Cassette drive interface port. RF Output-channel 3 or 4. Video output-composite/
chrominance/luminance. Audio input/output. Power supply input.
1

PLUS 4 PRODUCT SPECIFICATION (Continued)
FEATURES
Built-in extended BASIC 3.5 - over 75 commands. Built-in Machine Language monitor - over 12
commar.ds. Built-in graphics and sound commands. Screen window capability. Reset button (Warm
start). Built-in integrated productivity software.
PERIPHERALS
C1551 Fast Disk drive, C1531 Datasette, MPS 802 Dot matrix printer, MPS 803 Dot matrix printer,
DPS 1101 Daisy wheel printer, C1802 color monitor.
OTHER PERIPHERALS
C1541 Disk drive, MPS 801 Dot matrix printer, C1702 color monitor.
PLUS 4 OVERVIEW
The Plus 4 system is based on the 7501 microprocessor, an HMOS version of the 6510. Video pro-
cessing is achieved by the 7360 TED chip. 64K bytes of dynamic RAM are accomplished by 8 (64K
x 1) I.C.'s. (See page ). The system program is contained in 2 (16K x 8) ROMs. The system supports
up to 128K x 8 of ROM banked in 16K sections. By software control, through the 7360, ROM can
be completely banked out and RAM banked in for a true 64K of RAM (minus 256 byte pages), allow-
ing 60,671 bytes available for BASIC.
Keyboard and joystick scanning are accomplished by outputting the row data on the data bus while
addressing a particular register in the TED chip. This will in turn cause the TED chip to latch the column
information.
A standard serial port supports serial bus peripherals such as the 1541 disk drive and the various
serial printers. A cassette port is provided and the expansion port supports ROM cartrdiges. TTL serial
ASCII is intended to drive an RS-232 adapter.
2

PARTS LIST
PLUS/4
TOP CASE ASSY
Top Case
Keyboard,
67 Key, KKR-I
Nameplate
Shield Clip, R
Shield Clip, F
C 251453-01
C 251501-01
C 251655-01
C 251855-01
C 251856-01
BOTTOM CASE ASSY
Bottom Case
Foot, Self-Adhesive
Paper Shield
Shield Chip
Shield Plate
Insulation Sheet
C 251454-01
C 950157-04
C 310156-01
C 310199-01
C 310197-01
C 310198-01
ACCESSORIES
Users Manual
Power Supply
RF Cable
Switch Box
C 310196-01
C 310157
C 326189-02
C 904778-01
C - Commodore Stock Part

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PARTS LIST - PLUS/4 PCB ASSEMBLY #310163-01
PLEASE NOTE:
Commodore part numbers are provided for reference only and do not indicate the
availability of parts from Commodore. Industry standard parts (Resistors, Capacitors,
Connectors) should be secured locally. Approved cross-references for TTL chips,
Transistors, etc. will be available in manual form through the Service Department
in November of 1984. Unique or non-standard parts will be stocked by Commodore
and are indicated on the parts list by a "C".
DIODES (Continued)
INTEGRATED CIRCUITS
Bridge Rectifiers DBA20C
Sanyo 251026-03
Diode, Zener RD 6.8 EB 900927-01
Diode, IN 914 Sub: 900850-16
Diode, IN 4148 Taping 251819-21 Sub:
Diode, IN 4148 900850-01
CR1
(cont.)
CR2
CR11-20
7360 VLSI, Text Dislay (TED)
Sub: C 251535-01
8360 C 251535-02
7501 Custom Microprocessor
C 251536-01
6551 A (Synertek) 901895-02
74LS08 901521-03
6529B Single Port Interface
C 251640-03
901521-02
901522-06
901523-01
901521-57
901505-01
C 251641-02
901521-18
901521-34
901521-22
Ul
U2
U3
U4
U5
RESISTORS - All values are in ohms-1/4 W
5% unless noted otherwise.
74LS04
7406
555
74LS257
4164-2 D-RAM
7700-01 0 PLA
74LS139
74LS175
74LS27
2312B ROM TED Basic
U6
U7
U8
U9-10
U11-18
U19
U20
U21
U22
U23
240
250
lOOK
1.5K
47K
lOOK
3K
1K
1K
lK
1K
1K
R14
R15
R16
R17
R18
R19
R20
R21
R22
R23
R24
R25
4.7K
10K
470K
220K
18K
1.5K
470K
lOOK
1K
1K
12K
10K
lK
Rl
R2
R3
R4
R5
R6
R7
R8
R9
Rl0
R11
R12
R13
C 318006-01
23128 ROM TED Kernal C 318005-04
23128 FUNCTION ROM, 3 + 1 LOW
C 317053-01
23128 FUNCTION ROM, 3+HIGH
C 317054-01
6529B Single Port Interface
C 251640-03
U24
U25
U26
RESISTOR PACK
U27 3.3K, 6 PIN 902441-29
68, 8 PIN 4 ISOLATED 326149-06
RP1, 2
RP3,4
TRANSISTORS CAPACITORS
01-03
I 2SC 1815 902693-01 C1 Elect 0.1 µ,F25V 900100-40
04
I 2SD 880 902694-01 Sub: C2 Ceramic 0.1 µ,F25V 251075-06
Tip 29A 902653-01 Sub: C3 Film 0.22 µ,F 100V 900150-11
2SD 1266 902694-04 C4 Film 0.22 µ,F 100V 900150-11
C5-C6 Ceramic 0.22 µ,F50V 900022-01
DIODES
I I C7 Elect 2200 µ,F 16V 900101-33
C8 Elect 10 µ,F 16V 900100-25
CR1
I Bridge Rectifiers S2VB 10 Sindengen C9 Ceramic 0.1 µ,F25V 251075-06
215026-01 Sub: C10 Trimmer 40 pF
! 251029-02
Bridge Recitifers DBA20B Sanyo Cll Ceramic 22 pF 50V 251070-14
251026-02 Sub:
5

PARTS LIST - PLUS/4
PCB ASSEMBLY #310163-01 (Continued)
CAPACITORS (Continued) MISCELLANEOUS (Continued)
C12
C13
C14
C15-C16
C17-C18
C19
C20
C21
C22
C23
C24-C26
C27
C28-C29
C30
C31-C32
C33-C40
C41-C51
C100
Ceramic 220 pF 50V
251071-26 Sub:
220 pF 50V
150 pF 50V
Ceramic
Ceramic
Sub:
Ceramic
Ceramic
Ceramic
Ceramic
Ceramic
Elect
Ceramic
Elect
Elect
Ceramic
Elect
Ceramic
Elect
Ceramic
Ceramic
Sub:
Ceramic
Ceramic
Sub:
Ceramic 0.1
Ceramic 0.1
150 pF 50V
0.1 µF25V
0.1 µF 25V
10 µF 16V
0.01 µF 25V
10 µF 16V
0.1 µF 25V
10 µF 16V
1 µF 16V
0.1 µF 25V
10 µF 16V
0.1 µF 25V
10 µF 16V
0.1 µF 25V
0.22 µF 25V
0.22 µF 50V
0.1 µF 50V
µF 50V
µF 50V
MISCELLANEOUS
Y1
Y2
SW1
SW2
M1
Sub:
900463-08
251071-24
900462-41
251075-01
251075-06
900100-25
251075-01
900100-25
251075-06
900100-25
900100-16
251075-06
900100-25
251075-06
900100-25
251075-06
251075-07
900022-01
900020-06
9000010-01
900010-20
Crystal 14.31818 MHZ 251081-01
Sub:
Crystal 14.31818 MHZ 251081-02
Crystal 1.8432 MHZ 900555-02
Switch, Rocker C 251587-01
(PC Mount)
Switch, Push Button C 251260-01
RF Modulator C 251844-01
Sub:
RF Modulator 251311-01
FB2-14
FB15-21
FB22-26,
FB28-38,
FB40
FB41-58
FB59
FB60
FB61-63
FB64-65
EM1,2
CN1
CN2
CN3
CN4
CN5-6
CN7
CN8
L1
L2
L3,L3
F1
Ferrite bead
Ferrite bead 325563-01
903025-01
Ferrite bead 325563-01
Ferrite bead
Ferrite bead
Ferrite bead
Ferrite bead
Ferrite bead
903025-01
325563-01
903025-01
325563-01
903025-01
EMI Filter 251842-01
Connector 4 PIN (power supply)
C 251614-01
Connector 6 PIN DIN (serial bus)
C 903361-01
Connector 7 PIN MINI DIN (cassette)
C 251616-01
Connector 50 PIN Female Edge
(exoab) C 251630-01
Connector 8 PIN MINI DIN
(joy 1
& 2) C 251259-01
Connector 8 PIN DIN (audio/video)
325573-01
Connector 18 PIN (keyboard)
C 251841-01
Noise Filter
Line Filter
Sub:
Sub:
Coil Inductor 1.2 uHpt
Sub:
251264-01
906127-01
251701-01
901152-01
325570-01
Fuse 250V 1.5A
Fuse Clip
Cartridge Guide
Shield Box
Shield Cap
903556-18
906102-01
310171-01
C310172-01
C 310173-01
C - Commodore Stock Part
6

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or Q 2
w ~ ... ~
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-
2 39
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338
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437
-
5 36
-
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734
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833
-
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932
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10 31
-
7501
1-
11 30
-
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12 29
-
-
13 28
-
-
14 27
-
-
15 26
-
no.
16 25
-
-
17 24
-
-
18 23
-
-
19 22
-
,-
20 21
-
cj>OI N
RDY
-
IRQ
AEC
VCC
A
A
A2
A3
A4
A5
A6
A7
A8
A9
A1
A 11
A12
A13
GND
KEYBOARD MATRIX
RES
R/W
D0
D1
D2
D3
D4
D5
D6
D7
P0
P1
P2
P3
P4
P5
P6
GATE IN
A15
A14
A2
A1
A0
VDD
CS0
CS1
R/W
IRQ
MUX
RAS
CAS
cj>0
COLOR
CLK IN
K0
K1
K2
K3
K4
K5
K6
K7
SYNC
VSS
PIN ASSIGNMENT
U2-251536-01
CUSTOM MICROPROCESSOR
HELP
-
148
-
247
-
346
-
4 45
-
544
-
643
-
742
-
841
-
940
-
10 39
-
11
7360
38
12 37
-
-
13 36
-
14 35
-
15 34
-
16 33
-
17 32
-
18 31
-
19 30
-
20 29
-
21 28
-
22 27
-
23 26
-
24 25
-A3
-A4
-A5
-A6
-A7
-A8
-A9
-A10
-A11
-A12
-A13
-A14
-A15
-AEC
-BA
-SND
-D7
-D6
-D5
-D4
-D3
-D2
-D1
-D0
PIN ASSIGNMENT
U1-251535-01
VLSI, TEXT DISPLAY
(TED)

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M1 SCHEMATIC ON PAGE 11
PIN
CONFIGURATION
VSS
CSQ)
CS1
RES
RXC
XTL 1
XTLQ)
RTS
CTS
TXD
DTR
RXD
RSQ)
RS1
128
227
326
425
524
-
623
-
7
6551
22
-
821
-
920
-
10 19
-
11 18
-
12 17
-
13 16
-
14 15
-R/W
-Q)2
-IRQ
-D7
-D6
-D5
-D4
-D3
-D2
-D1
-DQ)
-DSR
-DCD
-VCC
U3-901895-02
ACIA
TRANSMIT/RECIEVE CHARACTERISTICS
CHARACTERTISTICS SYM -02 UNIT
2MHZ
MIN MAX
TRANSMIT /RECEIVE *
tCCY
CLOCK RATE 400
-
ns
TRANSMIT /RECEIVE tCH
CLOCK HIGH TIME 175
-
ns
TRANSMIT/RECEIVE tCL
CLOCK LOW TIME 175
-
ns
XTL 1TO TXD too
PROPAGATION DELAY
-
500 ns
RTS PROPAGATION tDLY
DELAY
-
500 ns
IRQ PROPAGATION tlRQ
DELAY (CLEAR)
-
500 ns
SYNERTEK ISYP6551A 12 MHZ
FE
17
16
15
14
13
12
I 1
IQ)
F7
F6
F5
F4
GND
PIN
CONFIGURATION
-
1 28
-
2 27
-
326
-
4 25
-
524
-
623
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722
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U19-251641-02
PLA
(tr, tf = 10 to 30 ns)
*The Baud Rate with External Clocking is:
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CS R/W
00-07
LLDATA BUS
TO PORT
LHPORT TO
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219
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318
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417
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U5/U27-251640-03
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U3, US, U19 PINOUTS ON PAGE 8
NC
DIN
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RAS
A(JJ
A2
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VCC
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CAS
PIN
CONFIGURATION
116
215
-
314
-
413
-
512
-
6
11
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7
10
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8
9
COMMODORE APPROVED VENDOR ACCESS POWER
PART SOURCE
1
PART TIME CYCLES ACTIVE STANDBY
NUMBER OF SUPPLY NUMBER
(ns) (ns)
(MW) (MAX)(MW)
901505-01 HITACHI HM4864-3 200 335 330 20
901505-01 NEC !-,PD4164-2 200 375 250 28
901505-01 MITSUBISHI M5K416NS-20 200 330 275 28
901505-01 MOSTEK MK4564N-20 200 345 300 22
901505-01 OKI MSM3764-20 200 330 248 23
901505-01 HITACHI HM4864P-3 200 335 330 20
901505-01 MATSUSHITA MN4164P-20 200 330 275 27.5
(PANASONIC)
901505-01 SIEMENS HYB4164-3 200 330 150 20
901505-01 SHARP LH2164-Z1 200 330 248 28
901505-01 HITACHI HM4864AP-3 200 330 242 20
901505-01 TOSHIBA TMM4164AP-20 200 330 275 22
-vss
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U11 - 18
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NC
A12
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A6
A5
A4
A3
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A1
ACIJ
D1
D2
D3
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D2
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128
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ROM - BASIC
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Q1. Q2: 2SC1684 OR EQUIVALENT.
L f (I
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LUH IN
RF oUT
t8
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AUDIO IN
L = H
03. 04: 1SS198 OR EQUIVALENT.
02 : 1SS110 OR EQUIVALENT.
01 : 1SS119 OR EQUIVALENT.
~u l
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TOP VIEW
-!1ft
CH4- 4 I "CH3
NO. TERMINALS
1
N.C.
2AUDIO SIG. INPUT
3
+B (+5V)
4
SYNC + LUM. SIG. INPUT
5COLOR SIG. INPUT
6
COLOR SIG. OUTPUT
7
COMPO. SIG. OUTPUT
8
SYNC + LUM. SIG. OUTPUT
9RF OUTPUT
10
CHANNEL SELECT SW.
'1
o
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,
RCA. PHONO JACK
D.ETAIL (CH.S'N)
,
tiLL
- -
REAR VIEW
RFModulator Layout and Schematic #251844
1 1

COLOR IN
LUI1 IN
i"B
AUDIO IN
RCA. PHONO
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01 : 1SS119 OR EQUIVALENT.
NO. TERMINALS
1N.C.
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3
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4
SYNC + LUM. SIG. INPUT
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TOP VIEW
D.ETAIL (CN.SH)
REAR VIEW
RF Modulator Layout and Schematic #251311 12

Issue 6, 1984 : Computer 3
.. commodore
Model: PLUS 4
© 1980 COMMODORE BUSINESS MACHINES INC.
Troubleshooting Aides
NOTE: Visual inspection is critical in this unit!
•
The upright position of many of the components used on the
board can create problems. It is possible for them to be
shorted to the shield or to each other. Make sure they are
evenly spaced and do not contact the shield.
Areas of the PCB particularly vulnerable to this
problem are:
Bottom right corner - caps
Bottom center - Jl-J6
Bottom left - Q3 shorted to FB57
Top left - ferrite beads
Center - Twisted caps (just outside of RF can)
1) NO VIDEO - Absolutely no video on screen
A) Check for 5 volts
O.K. If not: 1) Check fuse
2) Check for twisted or bent caps
+ ( 5 V. short to ground)
3) Check Ll
B) Check for oscillation at pin 14 of Ul
O.K. If not: 1) Check for good connection at
pin 14 of Ul
+ 2) Check for good connection at
Rl thru R7
C) Check for LUM signal at pin 23 of Ul, at pin 4 of
the modulator, at pin 8 of the modulator, at FB3
and at pinl of CN7
O.K. If not: 1) Check for LUM signal shorted
to ground
+ 2) Check for open traces
3) Check modulator
D) Check for reset
O.K.
+
E) Check for control signals:
Signal I.C. Pin Signal I.C. Pin
AEC Ul 35 R/W Ul 7
AEC U2 40Ul 12
CAS Ul 11 MUX Ul 9
CSI Ul 6IRQ Ul 8
CSl U20 15 RDY U2 2
CSO Ul 5BA Ul 34
CSO U20 1RAS Ul 10