IBM 3270 User manual

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IBM 3270
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Personal Computer
Maintenance
Information
SY27-2567-2

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IBM 3270
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Personal Computer
Maintenance
Infortnation
SY27-2567-2

Federal Communications Commission (FCC)
Statement
Warning: This equipment generates, uses, and can
radiate radio frequency energy and if not installed
and used in accordance with the instruction manual,
may cause interference to radio communications. It
has been tested and found to comply with the limits
for a Class A computing device pursuant to Subpart J
of Part 15 of FCC Rules, which are designed to
provide reasonable protection against such
in terference when operated in a commercial
environment. Operation of this equipment in a
residential area is likely to cause interference in
which case the user at his own expense will be
required to take whatever measures may be required
to correct the interference.
IBM Statement
The FCC statement is required for those machines that
are used in the United States.
CAUTION
This product is equipped with a line cord and plug
designed to avoid electrical shock. To insure
electrical safety, the user MUST supply a properly
grounded power receptacle.
Third Edition (October, 1984)
References in this publication to IBM products, programs, or services do not imply
that IBM intends to make these available in all countries in which IBM operates.
Any reference
to an IBM program product in this publication is not intended to
state or imply that only IBM's program product may be used. Any functionally
equivalent program may be used
instead.
Publications are not stocked at the address giv.en below. Requests for IBM
publications should be made to your IBM representative or to the mM branch
office serving your locality.
A form for readers' comments is provided
at the back of this publication. If the
form has been removed, address comments to IBM Corporation, Department 52Q,
Neighborhood Road, Kingston, N.Y. 12401. IBM may use or distribute whatever
information you supply in any way it believes appropriate without incurring any
obligation to you.
(~i Copyright International Business Machines Corporation 1983, 1984

Safety Procedures
This section provides safety practices for service
personnel, a
listing of the safety notices that
appear in this manual, and a safety inspection
checklist for the 3270 Personal Computer.
Service Personnel Safety
Practices
These safety practices include suggested safety
guidelines for service personnel working on
machines, first-aid if an accident occurs, and
reporting of accidents.
Rules for Safety
If (1) you know the safety rules for working with
electrical and mechanical equipment and (2) you
observe these rules, you can work safely with
IBM equipment.
Do not fear electricity, but respect it.
While you are maintaining IBM equipment:
1. Observe every safety precaution possible
2. Observe the following safety rules.
iii

Work Environment
IV
• Do not work alone under hazardous
conditions or near equipment that has
dangerous voltages. Always inform your
supervisor if the conditions or voltages are a
possible problem.
• Remove all power ac and dc when removing
or assembling major components, when
working in the immediate area of power
supplies, when performing mechanical
inspection of power supplies, and when
installing changes in machine circuitry. Pull
the power cable plug from the receptacle to
remove the power source.
• Always look for possible hazards in your
work environment. Examples of hazards are
moist floors, non-grounded extension cables,
power surges, and missing safety grounds.
• Do not perform any action that makes the
product unsafe or that causes hazards in the
work environment.
• Before you start the equipment, make sure
that other service personnel or employees are
not in a hazardous position.
• Do not wear loose clothing that can be
caught in the moving parts of a machine.
Make sure that the sleeves of your clothing
are fastened or are rolled above the elbow. If
your hair is long, or if you wear a neck scarf,
fasten it to make it safe.
• Insert your necktie into your clothing or
fasten it with a clip (preferably
non-conductive) at approximately 8
centimeters (3 inches) from its end.

• Lift the equipment or parts by standing or
pushing up with your leg muscles; this action
removes the strain from the muscles in your
back. Do not lift any equipment or parts that
are too heavy for you.
The maximum load to be lifted is that which,
in your opinion and management's, does not
jeopardize your own health or well-being, or
that of other employees.
• Put removed machine covers in a safe place
while you are servicing the machine.
Reinstall the covers before returning the
machine to normal operations.
• Always keep tools, tool kits and other service
items away from walk areas so that other
persons cannot trip over it. For example,
keep the kit under a desk or table.
• Observe good housekeeping practices in the
area of the machines while you are
performing maintenance and after completing
it.
• After maintenance, reinstall all safety
devices, such as guards, shields, labels, and
ground wires. Exchange safety devices that
are worn or defective. (Remember: the safety
devices protect you from a hazard. You
destroy their purpose if you do not reinstall
them when you have completed the servicing.)
v

Electrical Safety
VI
• If possible, always unplug the power-supply
cable before you work on a machine. When
you switch off power at the wall box, lock the
switch in the off position or attach a DO NOT
OPERATE tag (Z229-0237) to the switch.
Note: A non-IBM attachment to an IBM
machine may be powered from another source
and may be controlled by a different switch or
circuit breaker.
• Switch off all power before (1) removing or
assembling the main units of the equipment,
(2) working near power supplies, (3)
inspecting power supplies, or (4) installing
changes in machine circuits.
• Unless the maintenance documents
specifically instruct you, do not service the
following parts with power on if the part is
removed from its installed position in the
machine:
power supplies, pumps, blowers,
motor generators, and other units with
voltages that are more than 30 Vac or 42.4
Vdc. (This rule ensures that correct
grounding is maintained.)
• If you really need to work on equipment that
has exposed live electrical circuits, observe
the following precautions:
Ensure that another person who is
familiar with the power-off controls is
near you. Another person must be there
to switch off the power if necessary.
Do not wear jewelry, chains, metal-frame
eyeglasses, or other personal metal
objects. (Remember: if the metal touches
the machine, the flow of current increases
because the metal is a conductor.)

Use only insulated probe tips or extenders.
(Remember: worn or cracked insulation is
unsafe.)
Use only one hand while you are working
on live equipment. Keep the other hand
in your pocket or behind your back.
(Remember: there must be a complete
circuit for an electrical shock to occur.
This precaution prevents your body from
completing the circuit.)
When you use test equipment, set its
controls correctly and use insulated
probes that have the correct electrical
specification.
Do not touch objects that are grounded,
such as metal floor strips, machine frames,
or other conductors. Use suitable rubber
mats obtained locally, if necessary.
• Never assume that power has been removed
from a circuit. First check to ensure that the
circuit has been powered off.
• Do not touch live electrical circuits with the
surface of a plastic dental mirror. (Remember:
the surface of the dental mirror is conductive
and can cause damage and personal injury.)
• If an electrical accident occurs:
1. Use caution: do not be a victim yourself.
2. Switch off power.
3. Instruct another person to get medical aid.
4. If the victim is not breathing, perform
mouth-to-mouth rescue breathing. See
UElectrical Accidents"
under "First Aid."
Vll

Mechanical Safety
• Do not touch moving mechanical parts when
you are:
Lubricating a part
Checking for play
Doing other similar work.
• When using a stroboscope, do not touch
ANYTHING - it may be moving.
Safety Glasses
viii
Wear safety glasses when:
• Using a hammer to drive pins or similar parts
• U sing a power drill
• Using a spring hook to attach or remove a
spring
• Soldering parts
• Cutting wire or removing steel bands
• Using solvents, chemicals, or cleaners to
clean parts
• Working under any other conditions that
could injure your eyes.

Tools, Test Equipment, and Field-Use
Materials
• You should use approved tools and test
equipment. Make sure that electrical hand
tools, such as Wire-Wrap! tools and power
drills, are inspected regularly.
• Do not use worn and broken tools and test
equipment.
• Do not use solvents, cleaners, or oils that
have not been approved by IBM.
Summary
Prevention is the main aid to electrical safety.
Always think about electrical safety and use
good practice; for example:
• Make sure that the power receptacle used
matches the IBM equipment specifications.
• Inspect power cables and plugs: check for
loose, damaged,
or worn parts.
• Review the procedure in the maintenance
documents before you remove a part that can
hold an electrical charge from the machine.
Carefully discharge the necessary parts
exactly as instructed by the procedure.
• Do not use a normal light (for example, a
table lamp) as an extension trouble light at a
machine.
Trademark of the Gardner-Denver Co.
IX

x
Never assume that a machine or a circuit is safe.
No
machine is always completely safe. You may
not know the exact condition of a machine,
because, for example:
• The power receptacles could be wrongly
wired.
• Safety devices or features could be missing or
defective.
• The machine could have been damaged in
shipment.
• The machine could be deteriorated because it
is old or because it operates in an extreme
environment.
• A part could have become defective, thereby
causing a hazard.
• A part could be wrongly assembled.
Also:
• Make sure that all sales changes and
engineering changes are correctly installed.
These are some of the ways that the condition of
the machine could affect safety. Before you begin
a servicing procedure, use good judgment
and
extreme caution.

First Aid
Serious Injury:
1. Summon medical aid.
2. Do not move the victim unless absolutely
necessary, to remove him from danger.
3. Try to stop serious bleeding by using pressure
points or a pressure bandage.
4. Loosen the victim's clothing, and keep the
victim warm.
Electrical Accidents
When performing rescue procedures for an
electrical accident, do as follows:
• Use caution: If the victim is still in contact
with an electrical-current source, remove the
power; to do this, you may need to operate
the room emergency power-off (EPO) switch
or the disconnecting switch. If you cannot
find the switch, use a dry wooden rod or other
non-conductive object to pull or push the
victim away from contact with the
electrical-current source.
• Work quickly: If the victim is unconscious, he
or she may need:
Mouth-to-mouth
rescue breathing
External cardiac compression if the heart
is not beating.
INSTRUCT ANOTHER PERSON to call for
medical
aid such as an ambulance, rescue
service, or a hospital.
Xl

xii
Determine whether the victim needs
mouth-to-mouth rescue breathing. If he or she
does, perform the following steps.
CAUTION
Use extreme care when you perform rescue
breathing for a victim who may have
breathed-in toxic fumes. Do not breathe-in air
that the victim has breathed out.
1. Prepare for rescue breathing:
II
a. Ensure that the victim's airway is open
and that it is not obstructed; check the
mouth for objects that may be obstructing
the airway, such as chewing gum, food,
dentures, or the tongue.
b. Place the victim on his or her back, put
one hand behind the victim's neck, and
put the other hand on the victim's
forehead.
c. Lift the neck with one hand, and tilt the
head backward by pressing on the
forehead with the other handD.

2. Look, listen, and feel to determine whether
the victim is breathing freely:
a.
Put your cheek near to the victim's mouth
and nose.
b.
Listen and feel for the breathing-out of
air. At the same time, look at the victim's
chest and upper abdomen to see whether
they move up and down.
3. If the victim is not breathing correctly:
II
II
a. Keep the victim's head tilted backward
(see D). Continue to press on the
forehead with your hand; at the same
time, rotate this same hand.so that you
can pinch together the victim's nostrils
with your thumb and finger fJ .
b. Open your mouth wide and take a deep
breath. Make a tight seal with your
mouth around the victim's mouth II and
blow into the victim's mouth.
xiii

II
c. Remove your mouth to let the victim
breathe out, and check that the victim's
chest moves down 11_ .
d. Repeat steps band c once every 5 seconds
either until the victim breathes for himself
or herself or until medical aid comes.
Reporting Accidents
xiv
Report,
to your superior all electrical accidents,
possible
electrical hazards, and accidents that
nearly occurred. (Remember: an accident that
nearly occurs might be caused by a design
problem;
your immediate reporting ensures that
the problem will be solved quickly.)
Report, also,
all small electrical shocks.
(Remember: a
condition that causes a small shock
need differ only slightly to cause serious injury.)

Safety Notices
The safety notices that appear in this manual are
CAUTION statements. Read these statements
carefully to understand fully the risks involved
and the instructions.
CAUTION
Do not connect or disconnect a coaxial cable
during an electrical storm.
CAUTION
This product is equipped with a line cord and
plug designed to avoid electrical shock. To
insure electrical safety, the user MUST
supply a properly grounded power receptacle.
xv

Preparation
XVI
• For IBM Customer Engineers, completion of
one of the following is required:
"Electrical Safety Training Course for
IBM Customer Engineers"
"Primary Power and Electrical Safety"
(self-study
course number 70701 or current
level).
• Begin the checklist with the machine power
off
and the AC power cord(s) removed from
the power outlet.
• References:
3270 Personal Computer Guide to
Operations
3270 Personal Computer Maintenance
Information
Electrical Safety for
IBM Customer
Engineers (S229-8124)
Note: It is possible that not all machine
configurations (i.e. special features, RPQ's) are
covered. If you should encounter a machine with
features not described in this guide use the
installation instructions for that feature~
Otherwise use this guide and good judgment to
obtain a safe machine. Also, be sure to remove
any non-IBM OEM equipment from the machine
before applying power.

3270 Personal Computer Safety
Inspection Checklist
Start all safety inspections here.
_ Ensure that the work station is powered off
and all power cords for the work station
components are disconnected from the power
outlets.
_ Remove all apparent OEM non-IBM additions
before going any further with the safety
check.
_
Check for any cracks or damaged areas on
the face of the monitor CRT. Do not attempt
to remove the covers from the monitor; the
inside of the monitor is not to be accessed by
service personnel.
_ Try to determine whether or not the system
unit, monitor or keyboard have been
tampered with. Make sure that the covers
are not missing or damaged and are securely
fastened. Check for exposed sharp edges that
could cause possible injury.
_ Check for contamination, liquids, signs of
fire, or smoke damage for the entire work
station.
_ Check for worn, pinched, or frayed cables
(especially
the power cords).
_
Check to make sure the power outlet(s) match
the work station components voltage tag
requirements.
_ Check to make sure that you have less than
0.1 ohms between the ground pin and the
system unit frame. Check also the continuity
of the power cord receptacle for the
xvii

XVlll
monochrome display; from ground pin to the
frame the resistance should be less than 0.1
ohms (see figure 2.)
_
If the work station has a color monitor, check
the top and the bottom of the display to make
sure the plastic screw covers are in place.
_ Open the system unit by removing the larger
screws on the back of the system unit and
pulling the cover forward and up. Check to
make sure that the power supply is securely
fastened. (see figure 2).
_
Try to determine whether or not the system
unit power supply has been tampered with.
Either a "pop rivet" or a "bristle screw"
prevents access of the customer or service
personnel to the inside of the power supply.
Make sure that one or the other is in place.
Do not attempt to open the power supply.
_ Check the power cables for the presence of
ground pins. For detachable power cables,
check for continuity (less than 0.1 ohms) from
end to end (See Fig. 1).
_
Make sure that the "hazardous warning"
label is intact on the system unit power
supply.
_ Remove
any apparent non-IBM OEM
equipment from the inside of the system unit.
_ Check the inside of the system unit for
printed circuit cards that have become
unseated (out of their sockets).
_
Check the inside of the system unit for wires
or cables that have become pinched, frayed or
worn.

_ Check the inside of the system unit for loose
or open connectors.
_ Replace the cover on the system unit, and
fasten securely using the five screws which
were removed earlier.
_ If the workstation has a printer, check the
continuity of the power cord from the ground
pin to the frame. The resistance should be
less than 0.1 ohms.
_
Install the power cord(s) and plug them into
the power outlets.
_ Power up the workstation and observe the
results of the POST test on the CRT screen.
(See Section 1 of the IBM 3270 Personal
Computer Guide to Operations)
Abbrevia tions
CRT - cathode ray tube
OEM - original equipment manufacturer
POST - power on self test
~lX