Zenith Z-100 PC series User manual

SERVICE MODULE
Power Supply
Z-100 PC Series Computers
585-60-01 860-45
aNI'N data
~. systems

The purpose of this page is to make sure that all service bulletins are
entered in this manual. When a service bulletin is received, annotate the
manual and list the information
in the record below.
Record of Service Bulletins
SERVICE DATE CHANGED PURPOSE OF SERVICE INITIALS
BULLETIN OF PAGE(S) BULLETIN
NUMBER ISSUE
)
LIMITED RIGHTS LEGEND
Contractor is Zenith Data Systems Corporation of
St. Joseph, Michigan 49085. The entire
document is subjectto Umited Rights data provisions.
Copyright ©1984 Zenith Data Systems Corporation, all rights reserved.
Printed in the United States of America
Zenith Data Systems Corporation
St. Joseph, Michigan 49085

Contents
Record of Service Bulletins II
Figures III
Abbreviations
v
Chapter 1 Introduction and Specifications
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1
Chapter 2 Configuration
Chapter 3 Theory of Operation
Introduction .................................................... 3.1
Outputs ....................................................... 3.1
Power Supply Good (PSG) Signal ............................... 3.3
Operation at
No Load ......................................... 3.3
Chapter 4 Troubleshooting
Figures
2.1 Power Supply Rear View .................................... 2.1
3.1 Power Supply Output ....................................... 3.2
4.1 Power Supply Connectors ................................... 4.1

Abbreviations
CSA Canadian Standards Association
FCC Federal Communications Commission
KHz Kilohertz
ms millisecond
mV millivolt
PSG Power Supply Good
TTL Transistor-Transistor Logic
UL Underwriters Laboratories
VAC Voltage Alternating Current
VDC Voltage Direct Current
VDE German Engineers Association

Chapter 1
Introduction and Specifications
Introduction
WARNING: Do not attempt to service the power supply. Serious or fatal
injury may result.
This module provides information on the power supply. The power supply
as a unit
is NOT SERVICEABLE. The power supply contains ~roprietary
information. Therefore, there is no disassembly, parts list, reassembly,
or schematic included with this module. The specifications for the power
supply are listed below.
Specifications
Part Number: HE 234-434.
AC Input: 100-130 VAG, 60 Hz.
200-260 VAG, 50 Hz.
Switch selectable.
DC Outputs:
+5 V (±3%), +12 V (+5, -4%),
-12 V (+5, -4%).
Temperature Range: 10to 32°G.
47 to 89°F.

Chapter 2
Configuration
Refer to Figure 2.1 while reading the following.
The voltage switch at the rear of the computer is located through the
small window
on the power supply that is covered with plastic. The voltage
switch
is normally set for 115 VAC. If this computer is to be operated
on 240 VAC line voltage, use a small-bladed screwdriver and break the
plastic window over the 115 VAC position of the switch. Then slide the
switch so that 240 VAC is visible on the switch. Connect the appropriate
line cord.
@l')
~
~
~
®
~
,,
"
@.
~
0 0
§o
g~~~
§
~
@
[ _c.,,,,;,:; :'~:;':::.J ;.' 1
© "
, ,
"
,,
"
~
®
rft
00
, ,
, ,
00
,,
,,
"
~
@
[U
00
0 0
go
@
~
~
®
rf.;-
,'
00
og
0,
0 0
0 0
00
0 0
~
@
@
~
00
\
\
~
@
'--
'--
I....-
--
l....- I--
@
-/
POWER SUPPLY
Figure 2.1. PowerSupply Rear View

Chapter 3
Theory of Operation
Introduction
Refer to Figure 3.1 while reading the following.
The power supply provides regulated voltages used by the various compo-
nents within the Z-100
PC Series Computers. The power supply is located
toward the rear and to the right of the chassis, and uses a quasi square
wave switching regulator to produce three regulated output voltages. This
unit complies with FCC, VDE, CSA, and UL regulations.
Outputs
All outputs from the precision-regulated power supply are electrically iso-
lated from the main voltage and share a common ground, which is the
chassis of the power supply.
The voltages output to disk drive connectors P1 and P2 have special
requirements for output ripple frequency components
in the frequency
range of 60 to 120 KHz. To obtain these low levels, a low pass filter
is added to the regular output leads of P1 and P2. The output ripple is
measured with an oscilloscope with a bandwidth of 3 KHz. Component
frequency of the output ripple of the 5-volt or 12-volt outputs should NOT
exceed 2 mV peak between the frequencies of 60 KHz to 120 KHz. Con-
nector P3 supplies the output voltages to the backplane board.

Page 3.2
Theory of Operation
L----- .... ------------------ - 12 GR0 UND
-- ______ 1
NOTE: RESISTORS SHOWN ARE EXTERNAL LOAD RESISTORS.
Figure 3.1. Power Supply Output
+5V @
1.5A
+12V @
1.5A
+12V @
2.5A
+5V@
1.8A
+12 REG.
@ FULL
LOAD
1------- ...
P3 8 I
+5
+5V @ BALANCE
+5
FULL LOAD
GROUND
15 I
I
P1 I
I
I
151lH
151lH
+12
+ 12V @ BALANCE
+12
OF FULL LOAD
GROUND
~
r---------~~--~)~7--~----------------SPARE
)
~--~-----------------POWER
10 SUPPLY GOOD
)>-1-3---,1f----------------- POW ER FAIL
-12V AT
)>-4--!-------- - 12
FULL LOAD
...... -----t~-i---~>~-5-i:-----------------

Page 3.3
Theory of Operation
Power Supply Good (PSG) Signal
The PSG logic signal is an open collector TTL-compatible output which
is used by external circuits to determine if the output voltages are valid
and within specification. Upon power up, PSG shall remain high until all
the DC output voltages stay within specification for a minimum of 70 to
130 ms, after which time PSG will go low. If any voltage is not within
this normal limit plus 1% of nominal voltage (refer to Specifications), PSG
will go high. PSG will not return to a low condition until outputs have
met the same conditions as those required at initial power application.
Operation at No Load
The power supply is capable of operating under the adverse condition
of
no load without damage. If the power supply shuts down, it will require
a manual reset by turning the power supply off, waiting 5 seconds, and
then turning it back on. The output voltage may seek a value between
ground and 50% over nominal. Output voltages will not exceed the peak
rating ofthe output circuit components.

Chapter 4
Troubleshooting
Refer to Figure 4.1 while reading the following.
Measure the power supply outputs with the disk drive connectors discon-
nected, and connector
P3 connected to the backplane board. Measure
the voltages at the test points on the backplane board, and refer to Figure
4.1 for the power supply voltages.
Measure the ripple voltage with
an oscilloscope. If the power supply volt-
ages are normal, measure the voltage with the disk drives connected.
This will indicate if the circuit cards or disk drives are loading down the
power supply.
WARNING: The load resistors listed below generate heat. Use caution
to avoid burns.
NOTE: Voltages may not be within tolerance. The correct loads for the
output voltages are: +5
Vat 4 Amps (1.25-ohm resistor rated at 20 watts
or greater), +12 V at
tAmp (12-ohm resistor rated at 12 watts or greater),
and -12 V at 250 rnA (50-ohm resistor rated at 3.5 watts orgreater).
ROW 1
ROW 2
ROW 3
PIN
ORG+12V
ORG+12V BlK GND
WHT-12V
BlK
GND
BlK GND
ORG+12V
RED +5V
BlK GND
VEL PSG
RED +5V
BlK GND
BlU
PFL
RED +5V
BlK GND
ORG
Bl~ P2
BL~I~"'V
RED~j: m
ROW 3
ROW 2
ROW 1
TO DISK
DRIVE
Figure 4.1. Power Supply Connectors

SERVICE MODULE
Backplane Board
Z-100 PC Series Computers
585-64-02 860-45
aNI'. data
~ systems

The purpose of this page is to make sure that all service bulletins are
entered
in this manual. When a service bulletin is received, annotate the
manual and list the information in the record below.
Record of Service Bulletins
SERVICE DATE CHANGED PURPOSE
OF SERVICE
BULLETIN OF PAGE(S) BULLETIN
NUMBER ISSUE
INITIALS
LIMITED RIGHTS LEGEND
Contractor is Zenith Data Systems Corporation of St. Joseph, Michigan 49085. The entire
document issubjectto Umited Rightsdataprovisions.
Copyright ©1984Zenith DataSystems Corporation, all rights reserved.
Printed in the United States
of America
Zenith Data Systems Corporation
St. Joseph, Michigan 49085

Contents
Record of Service Bulletins
II
Figures Iv
Tables Iv
Abbreviations v
Chapter 1 Introduction and Specifications
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1
Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1
- 5 Volt Regulator .............................................. 1.1
Signal Bus .............................. . . . . . . . . . . . . . . . . . . . . . . 1.2
Chapter 2 Theory of Operation
Power Connector ............................................... 2.1
-5 Volt Regulator .............................................. 2.2
Diagnostic LEDs
............................................... 2.2
Backplane I/O Connectors
....................................... 2.2
Chapter 3 Detailed Circuit Description
Power Distribution ............................................... 3.1
- 5 VDC Regulation ............................................ 3.1
Diagnostic Circuitry .............................................. 3.2
Signal Bus .................................................... 3.2
Chapter 4 Troubleshooting
General Troubleshooting ......................................... 4.1
DC Voltages and Diagnostics .................................... 4.1
DC Voltage Checks ........................................... 4.1
Backplane Connector Fault Isolation ............................... 4.3
Chapter 5 Parts List
Introduction .................................................... 5.1
Component Parts List ........................................... 5.1
Semiconductor Identification Index ................................. 5.2
Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fold-in

Page iv
Contents
Figures
2.1 Backplane Board Block Diagram .............................. 2.1
5.1 Backplane Board Component Layout .......................... 5.3
Tables
3.1 I/O Bus Signal Names ...................................... 3.3

Abbreviations
ClK Clock
CPU Central Processing Unit
DC Direct Current
DMA Direct Memory Access
GND Ground
liD Input/Output
lED Light-Emitting Diode
mA Milliamperes
MHz Megahertz
NMI Non-Masked Interrupt
ns nanosecond
PSG Power Supply Good
ROM Read-Only Memory
VDC Volts DirectCurrent

Chapter 1
Introduction and Specifications
Introduction
The backplane board in the Z-100 PC Series Computer contains five sup-
ply voltage diagnostic LEDs, a - 5 VDC regulator, and the eight
IBM®-
compatible bus connectors, P101 through P108, into which the remainder
of the computer's cards are inserted for intersystem communication. A
power supply interface connector,
P11 0, and a +12 VDC connector, P109,
also are contained on this board. P109 supplies +12 VDC to an internal
video monitoron some models.
Diagnostics
The LEDs on the backplane board aid the user in determining whether
or not a fault lies in the DC power generation circuits. The five LEDs
on this board indicate the overall integrity of the power supply, and the
presence or absence of the four individual operating supply voltages: +12
VDC, -12 VDC, +5 VDC, and - 5 VDC.
-5 Volt Regulator
The only supply voltage actually generated on this board is the - 5 VDC.
The specifications forthis supply are as follows:
•
Input: -7.3 to -25 VDC, filtered by 2.2 JLF.
• Output: -4.8to -5.2 VDC, at 100 rnA, filtered by 47 JLF.
• Load: 1 rnA to 100 rnA, short-circuit protected.
•
Ambient Temperature: 0 to +70°C.
32 to 158°F.
"'IBM is a registered trademark of International Business Machines Corporation.

Page 1.2
Introduction and Specifications
Signal Bus
The eight-connector array on this board is basically an input/output (I/O)
extension
of the microprocessor bus. The bus interface is implemented
via a 62-pin edge connector on the card or device which plugs into one
of the eight backplane sockets. The bus supplies the following:
• Eight bits ofbidirectional data;
• Twenty address lines to access up to 1 megabyte of memory. The
maximum user memory is 640K of 64K devices, or 76aK using 256K
devices;
• Six levels ofinterrupt;
• Control lines for memory and I/O read and write;
• Clock and timing control lines;
• A channel check line for device error reporting or parity error reporting
by existing and add-on memory. A non-masked interrupt (NMI) is
supplied to the central processing unit (CPU) when this line is active;
• Operating power consisting of + and - 5 VDC, + and -12 VDC,
and ground;
•
An I/O CH RDY line for use by slowacting peripherals;
• Capability ofaddressing up to 64K I/O ports;
A complete listing of the signal names and their functions
is presented
in the "Detailed Circuit Description," Chapter 3.

Chapter 2
Theory of Operation
Refer to Figure 2.1, the backplane board block diagram, for the following
description.
-5VDC
-5VDC
REGULATOR
U101
(8) 1/0 BUS
CONNECTOR
~
-12VDC
P101-P108
POWER
CONNECTOR
+5VDC.
P1 10
y+
12VDC.
~VDC'- 12VDC,-' 'VDC
f:6'OM POWER SUPPL
-12VDC.
0~
PSG
PSG
DIAGNOSTIC +
+12VDC
ARRAY
(LEDS)
POWER
CONNECTOR
P109
TO VIDEO
•
DRIVER BOARD
Figure 2.1. Backplane Board Block Diagram
Power Connector
P110 from the power supply delivers the operating supply voltages for
the cards which plug into the backplane board connectors, and for the
diagnostic LED array contained
on the backplane board. System ground,
+5 VDC, +12 VDC, and -12 VDC are routed to the backplane board
by this connector. To increase the currentcarrying capability on the heavier
loaded supply busses and the ground return, more than one pin on the
connector
is used for the same supply bus. Ground and +5 VDC are
contained
in the middle layerofthe printed circuit board.
P109 supplies +12 VDC to the video driver board.

Page 2.2
Theory of Operation
-5 Volt Regulator
The - 5 volt supply is derived from -12 VDC from the power supply,
which is applied to a solid-state voltage regulator, U101. The - 5 VDC
is then applied to the parallel bus connectors, and to its respective diagnos-
tic
LED circuit.
Diagnostic LEOs
Five green light-emitting diodes (LEDs) are incorporated to indicate the
power supply is good, and the presence or absence of +5 VDC, - 5
VDC, +12 VDC, and -12 VDC. Suitable current-limiting resistors are
connected inline with the LEDs to provide the appropriate operating volt-
age and current to the devices. The LEDs are on (lit) when the parameter
associated with a device is at or near its stated value, and off when the
associated parameter is deficient.
Backplane 1/0 Connectors
Eight 62-pin edge-type socket connectors are provided by the backplane
board to interconnect the CPU card, the memory card, the video card,
and the disk controller card with the appropriate edge connector, as well
as any other cards which may be added for system enhancement or ex-
pansion. The optional connectors are identical and are wired in parallel
so that, functionally, any card may be inserted at any connector location.

Chapter 3
Detailed Circuit Description
Refer to the backplane board schematicfor the following circuit description.
Power Distribution
P110, the backplane power connector, connects + 5 VDC, + 12 VDC,
- 12 VDC, the power supply good (PSG) signal, and ground to the back-
plane board. Ground is connected to pins 3, 5, 6, 9, 12, and 15. + 5
VDC comes in on pins 8, 11, and 14. -12 VDC appears on pin 4. + 12
VDC is applied to pins 1 and 2. The PSG signal is on pin 10. Pins 7
and 13 are not used.
+5 VDC, + 12 VDC, and -12 VDC are fed through to B3, B9, and B7,
respectively, on the parallel signal bus connectors, P101 through P108,
and also are applied to their respective LEOs. -12 VDC also is fed to
the input, pin I of U1 01, the - 5 VDC regulator. Ground (GND) is routed
to the signal bus, pins B1, B10, and B31. The PSG signal is connected
to the cathode of 0104, the PSG LED.
-5 VDC Regulation
U101, the -5 volt regulator, accepts the -12 VDC on its input, drops
and regulates it, and sends the - 5 VDC output, pin 0, to bus pin B5,
and to R1 01, the dropping resistor for the - 5 volt LED. The G pin of
U101 connects to system ground to serve as a return path for the regulator
circuit. C119 and C117 filter and decouple the
-12 VDC input. C118
filters the - 5 VDC outputto reduce the ripple to
an acceptable level.