Hal Communications DS2000 User manual

HAL DS2OOO KSR VIDEO DISPLAY TERI1INAL
CUSTOMER MAINTENANCE MANUAL
Copyright O 1981 by HAL Communications Corp., Urbana, lllinois. Printed in the
United States of America. Al l Rights Reserved. Contents of this publ ication
may not be reproduced in any form without the written permission of the copyright
owne r.
|4arch, 198l Pr int ing
PRINTEO IN U,S.A.

DS2OOO KSR CUSTOIV]ER IVIAINTENANCE IVIANUAL
P reface:
This DS2000 Customer Maintenance Manual provides technical information
about the circuitry of the DS2000 KSR terminal and presents a step-by-step
troubleshooting guide. The DS2000 has been designed in a modular arrangement,
and the troubleshooting guide is designed to isolate problems to specific
boards whenever possible. When the defective module is located, please contact
the factory (or authorized HAL distributor) so that arrangements can be made fo!"
repair of the module, This approach should expedi te repairs of units and reduce
the danger of shipping damage that might occur if the entire terminal were
returned for repair. Since special test fixtures are required to test circuitry
on each board, it is highly recommended that repair of the boards themselves
be left to the factory or authorized-distributor technicians,
This manual is organized in six sections, presenting a discussion of the
circuitry, disassembly procedures, specifications and limitations, trouble-
shooting, adjustments and options, and schematic diagrams. lt is recommended
that you give all sections at least a cursory reading before beginning any
Les ts or measuremenLs.
The troubleshooting flow diagram has been prepared to utilize on-screen
symptoms and l,z0 tests, minimizing the amount of external test equipment
required. A good 20,000 ohms-per-volt VOM may be the only piece of test equjp-
ment you need! An oscilloscope is not required by the procedures given, but
may prove usefu I .
Problems with the D52000 can be placed in three general categories: those
due to internal component failures, those due to a hostile environment, and
those due to operator nisunderstanding. As with al1 electronic equipment,
some failure of internal circuitry may occur, particularly during the first
few weeks of operation, However, the factory "burn-in" testing and the
conservative design of the DS2000 have shown this mode of failure to be rare.
Equipment failures due to application of improper l/0 connections or
voltages, lightning strikes, or a hostiie environment (water or excess heat) ,
vary with the user. Experience has shown thbt the DS2000 problems can often
be traced to these sources.
Experience has also shown that improper operator understanding of the many
features of the DS2000 is often interpreted as an equipment malfunction. Please
double check your operating procedures before 'rdigging-intorr the troubleshooting
checks -- you may save yourself a lot of time and effort! lf you discover
a potentially confusing instruction in any of the manuals, please let us at
the factory know so that future versions may be ammended. Use this DS2000
Customer l',laintenance Manual in conjunction with your DS2000 0peratorrs Manual
and 0peratorrs Guide.
ltt

DS2OOO KSR VIDEO DISPLAY TERIvlINAL
CusromrR lVlRtuteunucr MRuunl
CONTENTS:
PREFACE. ttt
SYSTEI.I DESCR I PT I ON I
l.l System Block Diagram. I
1.2 CPU/Memory Sect ion . 1
l. P rog ram Memory. 4
2. Text Storage Memory 4
3. Z-BO CPU. . 4
1.3 lnput/Output Section. 4
l. Keyboa rd. 4
2. f/0 Connections . .. .7
3. Receive Loop Detect . 7
I.4 Video Generator Section . 7
1.5 Audio Input lnterface Section (MR2000) .10
2. DISASSEMBLY OF THE DS2OOO.
2.1 Introduction.
2.2 Remova I of MR2000
2.3 Removal of Power Supply
2.4 Removal of Logic Board.
2.5 Reassembly of DS2000 KSR. 13
2
4.
I/O SPECIFICATIONS AND LIMITATIONS .I5
TROUBLESHOOTING PROCEDURES FOR THE DSzOOO KSR. .17
4.1 lnitial Connector Check .17
l+,2 Returning Equ i pment .17
4.3 Using The Flow Chart. .19
4.4 Troubleshooting Guide .19
2. Typ ica I Display?. .20
3. Loop, KOS and C\,/ Lines Key 0K?. .20
4. RX Morse 0K?. .21
5. Bell Tone 0K? .22
6. 0ther Problems.... ,22
4.5 RF- lnduced Problems ,22
\-6 Minimizing Rf-Related Problems/Antenna Seiect .26
ADJUSTMENTS AND OPT I ONS. ,29
5,I Sidetone Adjustments. .29
5-2 0ptional Sidetone output. .29
5.3 Modification for Operation/50-Hz Line Frequency .32
5.\ Modification for 0peration/69-Charact. Video Line .32
ILLUSTRAT IONS. .35
5.1 Table of Contents - lllustration Section.
E
6. .35

F I GU RES :
.I KSR Subassembly-0riented Block Diagram I
.Z DS20OO/MR2000 Block Diagram (functional). . . . .3
.3 CPU/Memory Section of DS2000 Circuitry, .5
.4 l/0 Section of D52000 Circuitry . 6
.5 Block Diagram of Video Section of DS2000. B
.6 Block Diagram of MR2000 Circuitry 9
3.
4.
Chassis Position for lnstallation/Removal of MR2000
DS2000 l/0 Connections.
Troubleshooting Flow Chart.
2
6
8
4..2
4.3
5.1
E,)
c1
5.4
o.l
o.z
6.3
6.4
6.5
6.6
o. t
6.8
6.9
6. i0
6.1r
Cable Arrangements and Use of Ferrite Materials to Reduce RF. .24
Simple RF-Bypass and Brute-Force Methods of RF El imination. .25
Location of Jumpers, Sidetone Vol. Pot and C, R", Rg. .30
DS2000 Sidetone Oscillator Component Selection Chart. .31
Location of Optional Sidetone-Output Circuit Pad rrSrr. .32
Location of Optional Sidetone-Output Connector Pin 3. .3\
CPU/Memory Schematic Diagram (A-1352) .36
lnput/0utput Schematic Diagram (A-,|353) .37
Video Generator Schematic Diagram (4-1354) .38
Power Supply Schematic Diagram (A-1355) .39
MR2000 Audio lnput lnterface (A-1354) .40
DS2000 External View of Complete Unit . .41
Cabinet Top Removed From Lower Chassis, . .\2
Lower Chassis with Top Section (logic board) Removed. .\3
Top View of Logic Board, Showing Keyboard ,44
Bottom View of Power Supply Board .\5
View of Back Side of MR2000 Board, Pot C E Connector .\6

THE DS2OOO KSR COIvll4UNICATIONS TERI4INAL
1. SYSTElvl DESCRIPTION
Circuitry of the DS2000 KSR is contained primarily on three printed
circuit boards (two, excluding the MR2OOO option). These are the power supply
board, the logic board, and the MR2000 Morse receive board, Fig. l.l shows
the basic interconnections between these subassemblies. Each subassembly has
a numerical designation, which is used to identify it. These designations
appear on each pc board to help make identification easier.
l.l System lllock Diagram
Fi9. 1.2 contains a functional block diagram of the entire KSR,
including the MR2000 option. Like other HAL terminals, the DS2O00 is designed
around a dedicated microcomputer, the heart of which is a type Z-80 B-bit
microprocessor lC. The Z-80, along with i ts associated anci I lary devices,
controls all KSR operations. The kinds of devices directly interfaced with
the Z-80 in the DS2000 are as follows: Read-0nly Memory (i,Ou), Random-Access
ttemory (RAM), Cathode-Ray-Tube Control Ier (CRT Control ter or CntC), Keyboard
Matrix, lnput/0utput (l/0) lnrerface Circuitry, and the MR2000 Morse Receive
Circuitry. Other devices, such as the line buffer, character generator, and
video combining circuitry, are interfaced directly with the CRT controller,
which can directiy access memory, as necessary, during video display routines.
Communication between the Z-80 and its ancillary devices is through
the bi-directional data bus, address bus, and control signals such as l/0
Read/write and Memory Read/write. Operation of the z-80 central processing unit
(CPU) requires that a multitude of commands, data and address information be
communicated on a common mul ticonductor data bus. A system of tri-state
buffer/driver devices actuated by commands from the Z-80 and gRT Controller,
along wi th two types of interrupts, ensure that inter-device communications
are carried out properly on this rrparty line,r, The two types of interrupts
used on the z-80 CPU are software maskable (lNT) and non-maskable (Ntii-).
Maskable interrupts can be " i g no reTil-6!--il-e CpU if rhey happen at other than
specific times during program execution, whereas non--maskable interrupts must
be serviced by the CPU as soon as it completes the current.program instruction
being executed. lnterrupts will be discussed in more detail when the circuitry
that generates them is analyzed.
The DS2000 KSR operates differently than all previous HAL amateur
terminals in that the Z-80 shares control of the address and control buses
with the 8350 CRT Controller, ln this system, the CRTC is said to be operating
in Direct-Memory Access (OUn) mode when it takes control of the buses from
the Z-80 CPU. How this system operates is explained in more detail in the
sections of text that deal with the CpU and CRTC.
1.2 CPUIMEMORY SECT ION
The CPU/Memory section of the
form in Fi9. 1.3, and schematical ly in KSR circuitry is shown in block-diagram
Fis.6.l.

VIDEO OUT
I/O LINES:
LOO P
CW KEYING
K0s
MORSE AF INPUT
FlG. 1.1 -- Block diagram of pc-board interconnections in DS2000.
POWER
SUPPLY
(D 1 r43)
PRO CESSO R/VID EO
BOARD WITH KEYBOARD
(D 1 139A)
MR2()OO MORSE AUDIO
INTEBFACE
(D 1 146)

L!L
F=
6o
o^
=E
5o
(-)>
(.5
i=
z>
OUJ
(J:Zo-o-=
e u33*
:. E))=.n
o QXxuJo
F > F aC .o :Z
F
3
o
o
!J
Cf
=
o
C
o
u
c
a
E
r0
q,
r0
p
(.)
o
-o
o
o
N
d.
=
o
a
o
N
o
I
I
N
<5
J
=
(j)
a
J
o
F
z.
O
CJ
o
LLI
o
=
.E OE
LIJ O
FF
(-)<
<cc
.E LIJ
<2.
:EUJ
(J (9
CE
UJ
J
J
C)
!c
F
z.
o
()
F
E
(J
=
l!
tl-l
at,
t,
o
=

I . I)roc_l t-,ti I fleficry
l"i1 op-.craticn5 prIformed by ihe DS?000 circuitty are deternrined
by sc(rirl,r'ri ial stcps in the 1,.:, r. erl prcgra . Thir Prcgranl, v"iliclr c()niains all
necessarv insiruclions for the tricrcpr,rt:cs-.or, li a(irltained in Pro'lrartlrlabic
ile ai-0rly Henrory (PRoM) . Iar1y DS20C0r LonL;ri]r 1-(rui J,;'pe 2;CS tra:.rirl(. PllC11i,
while the neu,Jesl versions conr-ain ar single masl.-1;i-C1t r;rrrr:rabit: R0l'1 T;oica1
sL!!rout incs ihal arc slorcd in lhe KSR PR0il arr; l<er'iboard (iacod;nq, charar:ler
siorage, speeC clranlie. c.-.de conversion, stal us iriocessor, :nd test flle:sage
generation. The p i-,.,,g rail irifcrmation stored in ircntory devicc.' is L-ften referred
to as "sof tr^riii-e" to distinguish it from the harcj-r.iired or "lrard,.'areI part cf
the system. The software in the DS2000 is iirstalleC in pluq-in !ockets,
as:,uring simpii replacernent if future sof i!i.lr.i-' upcli]le! aie rraLlc a"railable .
2. Text 5 toraqe liemory
The DS2000 KSR Iogic board conlains 3 kilobytc , of R.tndom-Acces:l
to store all text in the vicleo bul-fr:r (1728 cira;ac*.er:)
hidden buffer. six static RAl"1 lCs (each 1k x E l-.its)
whether it is being dispiayed or stored ;n the
Menro-y (RAM) , wh j ch
along l.rith the text
are used to store al
s used
n the
text,
h idden i i-ansm i t buffer.
3. z*80 cPU
The D0TCLK siqnal f rorn the CRT Controller is divided do!',/n to
generate the Z-80 clock and IIT signals. The fr equency of the non-maskable
interrupt is 2.1328 kHz, pr-oviding an interval of approximateiy 0.47 mS betv/een
NMls. The DS2000 software prograrq is interrupLed each time an N14l occurs,
providing a regular time-referenced "stopping point".
Two_Algna I s interface the Z-80
BUSEN. The H0LD signal is generated by
This signal goes to the BUSRQ input on
being performed and then removes itself
along with another Z-80 control signal
are used to enable or select al I ancil
from the l..1R2000 board is connected to
CPU with the CRT Controller: H0LD and
the CRTC to request control of the buses.
the Z-80, which completes the instruction
from the buses by tri-stating (going
-- ll0 Request (l0Rq) -- and address 'l ines
lary devices. The INTRP contrcl line
the maskable interrupt (tUf) on the Z-80.
to a high impedance) at all address- and data - bus connections. After the Z-80
has gone tri-state, it acknov./ledges the bus request with a BuSAR signal that is
used to enable the CRTC as a BUS Enable (AFSEN) signal.
Additionai control signals from the Z-80 are used to create Memory
write (tlEyWR), Memory nead (MElln) , t/O wri te -(10!ln), and l/0 nead (l0RD). These,
r.3 INPUT/OUTPUT SECT ION
(A b lock diagram depicting
is contained in Fiq. 1.4.)
Keyboa rd
ln the DS2000 KSR, the
memory device. Performing a part of
software, the Z-80 scans the keyboard
of the data lines, representing a key
the l/0 section circuitry in the DS2000
keyboard is treated as a read-only type
the main service routine in the system
natrix looking for a logic zero on one
press oo a specific key. lf a key press
4

FROM CR]
OOT CLK
cRr2
*l TO CRTC
t0 R0
ADD. BUS DATA BUS
EKBSW
(T0 r/0 sEcTt0N)
MEMB
INTRP
(FBOM MB2O()t))
MEMW
IO RD
IOWR
r0 R0
FlG. 1.3 -- CPUlMemory section of DS2000 circuitry.
BUSAK
E[-usRo
CLK
2"80
Nmi
m
DECODE/SELECT
D E CO D E/SE LECT

BDAUX
E KBSW
AODRESS
LiNES
FROIV] I/O CI]NNECTOR
Ao
ro-WE
)
I
t
) T0 r/0 c0NNEcroR
I
I
)
TO SPEAKEB
FlG. 1.4 -- l/0 section of DS2000 circuitry,
cJ7
:)
od
F
o
DRIVERS CONTROL & SHIFT
KEYSWITCH ES
DRIVEBS KEYB OA R D
MAT R IX
BX IOOP
D ETECT
DECODE TX LOOP
KEYING
vo
LATCH CW KEYING
BELL TONE