IBM 5475 User manual

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- - - =: ~ §: Maintenance Library
Elastic Diaphragm Encoded Keyboards
and 5475 Data Entry Keyboard
Theory-Maintenance Manual
SY27-0073-1

Preface
This manual covers both the theory of operation and the
maintenance for keyboards using Elastic Diaphragm
Switches. It is intended for use by the Customer Engineer.
The manual is divided into two major parts: Part 1
contains the FE Theory of Operation and Part 2 contains
the FE Maintenance Documentation. In addition,
Appendix A covers information peculiar to the 5475
keyboard and its use with a system. This information
consists of keyboard layouts, connector and code charts,
diagnostic flowcharts, and differences from the basic
keyboard. Information peculiar to other keyboards and
their use with a system is covered in the using system's
documentation.
No companion or prerequisite manuals are necessary
for use with this publication.
Second Edition (March 1971)
This is a major revision of, and makes obsolete, SY27-0073-0. It includes additional line
drawings to enhance both the theory and maintenance sections. Associated changes to
the text and illustrations are indicated by a vertical line to the left of the change. New
material, added to Parts 1 and 2, covers the new encode board and elastic diaphragm
switch assembly. These additions, being entirely new, are not marked with vertical lines;
they can be easily located by use of the table of contents or the index.
Changes are periodically made to the specifications herein; any such changes will be
reported in subsequent revisions or Technical Newsletters.
This manual has been prepared by the IBM Systems Development Division, Publications
Center, Department EOl, Building 060, Research Triangle Park, North Carolina 27709.
A form for reader's comments is provided at the back of this publication. If the form
has been removed, comments may be sent to the above address.
© Copyright International Business Machines Corporation 1969, 1971

Part 1. Theory of Operation
Introduction .
Functional Units
Principles of Operations
Key Mechanisms
Latch Key Operation
Momentary Key Operation
Typamatic Key Operation
Elastic Diaphragm Switch
Encode Circuit Board
Bail Drive Card .
Shift Key
New Encode Circuit Board and Switch Assembly
Part 2. Maintenance
Preventive Maintenance
Lubrication .
Figure Title
1-1
Keyboard: Elastic Diaphragm Encoded
(Example)
1-2 Latch Key (Normal Position)
1-3 Latch Key (Operated Position)
1-4 Latch Key (Restoring) .
1-5
Uall Interlocks
1-6 Momentary Key (Normal Position)
1-7 Momentary Key (Operated Position) .
1-8 Typamatic Key (Single Cycle Operation)
1-9 Typamatic Key (Repeat Operation)
1-lOA Elastic Diaphragm Switch Asm. (EDS)
1-lOB Elastic Diaphragm Switch Asm. (EDS)
1-11 Elastic Diaphragm Switch Substrate
1-12 Encode Board
1-13 Encode Circuits (Example)
1-14 Restore
Uail Interposer and Latch Interposer
Comparison
1-15 Shift Key Lock Mechanism
1-16 Redesigned Encode Board and Switch Asm.
1-1
1-1
1-1
1-1
1-1
1-1
1-4
1-4
1-6
1-7
1-9
1-9
1-10
2-1
2-1
2-1
Page
1-1
1-2
1-2
1-3
1-3
1-4
1-5
1-5
1-6
1-6
1-7
1-8
1-8
1-9
1-9
1-9
1-10
Cleaning .
Maintenance .
Checks, Adjustments, and Removals
Key Lever
Interposer
Restore Bail and Magnet Assembly
EDS Latch Spring and Actuator .
New Encode Board and Switch Assembly
Ball Interlock Assembly
Space Bar Assembly
Shift Key Mechanism
Appendix A. 5475 Keyboard
Index .
Contents
2-1
2-1
2-1
2-1
2-2
2-3
2-4
2-5
2-5
2-6
2-6
A-1
X-1
Illustrations
Figure Title Page
1-17 Encode Circuits (New Style Encode Board) 1-11
2-1 Latch Key Adjustments 2-2
2-2 Interposer to Guide Comb Clearance . 2-2
2-3 Dabber Adjustment (To Lower Dabber) 2-3
2-4 Dabber Adjustment (To Raise Dabber) 2-3
2-5 Momentary Key Interposer Overtravel 2-3
2-6 Bail Adjustments 2-4
2-7 Bail Stop Adjustment . 2-4
2-8 Latch Spring and Actuator Adjustment
2-5
2-9 Encode Board and Diaphragm Replacement 2-5
2-10 Ball Interlock Assembly Adjustment .
2-5
2-11 Space Bar Operating Tab Adjustment 2-6
A-1 5475 Keyboard Arrangement .
A-1
A-2 System/3 Card Code A-2
A-3
5475 Electrical and Mechanical Timings
A-3
A-4
Control Panel A-3
A-5 5475 Interface Connectors
A-4
A-6 5475 Control Panel Connectors
A-5
A-7 5475 Keyboard Diagnostic Flow Chart
A-6
iii

INTRODUCTION
The keyboard is a manual entry device providing coded
outputs to the using system through cable connections.
Different models'provide various codes, key configurations,
J and control keys for the using system (Figure 1-1 ). A
circuit board creates output codes that are compatible
with the coding scheme of the system. The system samples
• the bit output lines and signals the keyboard reset. The
keyboard can be used for entering data or for inquiry by
the use of the data keys. The keyboard control keys can
format data or can control functions for various output
devices.
Keyboard interlocking prevents pressing two latch keys
at the same time or pressing a second latch key before a
keyboard cycle is complete. The using system locks the
keyboard when it is not in use. It is locked when power
is off.
Refer to the keyboard pictured in Figure 1-1 for
locations and orientations used throughout this manual.
FUNCTIONAL UNITS
The information usually found in the Functional Units
section has been incorporated in the Principles of Operation
section.
• All locations and directions are referenced from the operator
• Front of tho keyboard· Portion closest to the operator
• Right and left of the keyboard -Operators right and left
• Key rows -First row is farthest from the operator and the
fourth row is tho closest to the operator
I Figure 1-1. Keyboard: Elastic Diaphragm Encoded (Example)
Part 1. Theory of 0 peration
PRINCIPLES OF OPERATION
Key Mechanisms
The keyboard may include three types of keys, depending
on the model: latch keys, momentary keys, and typamatic
keys. A latch key provides on·e coded output to the
interface lines each time the key is pressed. All graphic
keys and some control keys use the latch key mechanism.
A momentary key provides an output to the interface only
while the key is held Clown. Most control keys or function
keys use the momentary key mechanism. When a repetitive
function is desired, graphic or control keys use the typamatic
key mechanism.
Latch Key Operation
Pressing a latch key (Figure 1-2) pivots the keylever on its
fulcrum rod. The dabber transfers the downward motion
to the interposer. A latch spring rests against the rear of
the interposer. As the interposer moves down at the rear,
the latch spring moves forward over the interposer (Figure
1-3). The latch spring latches the interposer down and
closes the associated elastic diaphragm switch (EDS).
Closing an EDS makes a circuit to the encode circuit board,
which generates coded outputs and a signal indicating data
is available.
Elastic Diaphragm Enc Kybds and 5475 Data Entry Kybd (3/71) 1-1

front _..,. ____ ..:..,.. ... Rear
Restore Magnet
Figure 1-2. Latch Key (NormalPosition)
Restore Bail
figure 1-3. Latch Key (Operated Position)
1-2 (3/71)

When the 'data available' signal and the data character
are accepted by the system, power to the restore magnets
is dropped. The keyboard restoring bail moves to the
front of the keyboard (under spring tension) carrying the
latched interposer with iL An elongated interposer pivot
hole allows the interposer to move to the front, clearing
the latch spring (Figure 1-4). The interposer return spring
forces the interposer up off of the bail and behind the latch
spring. The interposer pushes the latch spring to the rear,
allowing the EDS to open.
As the interposer moves to the rear, the interposer
projection strikes the <lobber, and pivots it from its rest
position. When the keylever is released, it pivots upward
and the <lobber return spring restores the <lobber to its
normal position above the interposer.
As the bail moves to the front, it moves under all the
unoperated interposers (Figure 1-2) and prevents them
from operating. While the keyboard restore bail travels
toward its forward stop, the bail contacts (which are EDS
switches) close, providing the 'bail contact' or 'restore'
signal to the system, or keyboard logic. This indicates the
bail has traveled its full restoring stroke and the restore
magnets can again be energized. The keyboard remains .
locked and the 'bail contact' or 'restore' signal remains
until the restore bail magnets are picked and sealed.
The 'bail contact' or 'restore' signal drops the 'data
available' signal and holds it reset. These electronic inter-
locks allow the time for the EDS switch to open. Thus,
there is only one output from the keyboard for each latch
key pressed.
Figure 1-4. Latch Key (Restoring)
The keyboard is locked by the ball interlock (Figures
1-3 and 1-5) while the interposer is latched down. An
operated interposer goes between the interlocking balls
and takes up the· clearance between the balls. Other inter-
posers can not be operated until the first one is restored
because the balls can not separate to allow another inter-
poser to enter. The keyboard is locked by the restore
bail during restore time. Therefore, the next key cycle
can begin only when the restore magnets are again picked
and sealed.
lnte,pom• n
c:Qo
Ball Interlocks
Figure 1-5. Ball Interlocks
Interposer Return Spring
Elastic Diaphragm Enc Kybds and 5475 Data Entry Kybd (3/71) 1-3.

I
Momentary Key Operation
Momentary control keys do not provide a coded output to
the interface bit lines, but do activate a control line to the
keyboard interface. The momentary key interposer, unlike
the latch key interposer, has a link (Figure 1-6) that operates
on the latch spring, and the pivot hole is not elongated.
As the key is pressed, the <lobber moves the interposer
down, causing the link to pivot (Figure 1-6). The latch
spring closes the EDS as it follows the arc ot the link
(Figure 1-7). The interposer is not latched down by the
latch spring, and the using system determines if a keyboard
restore cycle occurs as a result of pressing a momentary
key. The circuit through the EDS remains closed as long
as the key is held down.
When the key is released, the interposer is restored by its
return spring and the link cams the latch spring away from
the EDS.
Typamatic Key Operation
When a typamatic key is held down with a slightly more
than normal pressure, it permits automatic repetition of a
graphic, space,. or function key. Normal pressure on the
key causes only one operation, as with a standard latch-
type key.
The typamatic keylever (Figure 1-8) has a typamatic
latch pivoting on the keylever at the front. When the
keylever is pressed, the typamatic latch downstop strikes
the top of the interposer fulcrum. This is the normal stop
for the typamatic keylever, and actions of the <lobber,
interposer, and switch are identical to a standard latch key
Figure 1-6. Momentary Key (Normal Position)
1-4 (3/71)
mechanism. Additional pressure on the keylever overcomes
the typamatic latch spring tension, causing the latch to
pivot downward from the keylever. The turned-over ear
on the typamatic latch then strikes the top of the interposer
projection, and holds the interposer down in the latched
position. When the restore magnet is de-energized during
this cycle, the restore bail moves the interposer to the front.
The turned-over ear pivots down behind the interposer
projection (Figure 1-9) and holds the interposer forward.
The interposer remains in this position, with the EDS closed,
until the key is released. Data is sampled by the system
until the interposer is restored and the EDS switch opens.
When the keylever is released, the interposer restores
immediately. The interposer return spring pulls the inter-
poser to the rear of the keyboard, where it strikes the latch
spring and allows the switch to open. The electronic circuits
complete the keyboard cycle that may already be in progress
by providing proper timing for the data lines and the 'data
available' signal (refer to the timing chart for the 5475 in
Appendix A).
Another method can begin a typamatic operation. If
the keylever is not pressed to its limit soon enough, a full
restore cycle occurs. The <lobber is out of position because
the keylever is down. If the keylever is pressed to its limit
at this time, the turned-over ear of the typamatic latch will
strike the interposer projection. The interposer will move
down and latch under the latch spring. As the restore
portion of the cycle begins, the interposer will again move
behind the turned-over ear of the typamatic latch and will
be held in this position until the key is released. The
remainder of the operation is the same as the first repeat
operation described.

\nterposer Return Spring
--- Latch Spring
Link
Figure 1-1. ).\omcntatY J{eY (Operated Fosition)
f igUfC 1-S. 'fypamatic J{ey (Single Cycle Operation)
ElasticDiaphragm Enc J{ybd> and 5415 DataEnttY J{ybd (3/11l 1-5

Figure 1-9. Typamatic Key (Repeat Operation)
I Elastic Diaphragm Switch (Old Style)
The EDS (elastic diaphragm switch assembly) consists of a
substrate, a separator, an elastic diaphragm, a Mylar* spacer,
a slotted clamp, a spacer, an actuator spring, a beveled
spacer, a latch spring, and a clamp (see Figures 1-lOA and
1-lOB). The substrate is flexible plastic, with copper-ribbon
land patterns running from the EDS to the encode circuit
board assembly (Figure 1-11 ). The land patterns laminated
on the substrate terminate at one end in a solder connection
to the encode circuit board and at the other end behind a
hole in the separator. The end behind the separator hole is
Figure 1-lOA. Elastic Diaphragm Switch Asm. (EDS)
1-6 (3/71)
Turned-Over Ear
lnte1poser Projection
the N/O contact of an elastic diaphragm switch. The plastic
diaphragm of the switch has a laminated conductor that is
electrically common to all the switch positions. The
separator layer, which separates the substrate and diaphragm,
contains holes aligned with each of these contacts. The sub-
strate, separator, and elastic diaphragm are clamped together
to the rear of the keylever support (Figure 1-lOB). When
a latch spring is released, the elastic diaphragm is pressed
through the hole in the separator by the actuator spring
projection. The diaphragm common conductor contacts
the N/O contact on the substrate, which completes the
circuit to the encode circuit board.
....,--Spacer
!+--- Actuator Spring
,....,.."'/1-+--- Spacer
Latch Spring
Clamp

Fulcrum
--
-
_.-
Actuator Spring
Latch Spring
Figure 1-lOB. Elastic Diaphragm Switch Asm. (EDS)
I Encode Circuit Board (Old Style)
The encode circuit board (Figure 1-12) attaches to the top
of the keyboard side frames and can be pivoted for access
to the mechanical portions of the keyboard. The SLD
logic circuits receive inputs from the elastic disphragm
switches to initiate outputs to the using system. Control
inputs from the using system control keyboard operations.
SLD logic encodes the inputs from the EDS into the code
of the using system and routes these codes to the system
interface. Connection to the interface is through pluggable
SLD connectors at either side of the circuit board.
Actuator Spring
Substrate
The elastic diaphragm switch completes a circuit through
the encode board diode matrix or logic block depending on
the model (Figure 1-13). This input ANDs with the shift
mode (uppercase or towercase) and sets the appropriate bit
latches. The 'bit' latch outputs are ORed to generate a
'data available' signal. 'Data available' indicates to the
system that a key is down and the 'bit' lines are up.
In some models, the 'data available' signal is the hold and
reset for the 'bit' latches. When accepting data, the system
drops its hold on the restore magnets. The restore bail then
operates the restore bail interposer, closing the bail contacts
(Figure 1-14), which generate a 'bail contact' signal in the
encode board. 'Bail contact' resets the 'bit' latches.
Elastic Diaphragm Enc Kybds and 5475 Data Entry Kybd (3/71) 1-7

Figure 1-11. Elastic Diaphragm Switch Substrate
• •
• •
• •
N ••
2 : :
~ ..
c ••
8 ••
II@
I
Encode Board
Encode Board
land Patterns
013
• •
• •
• •
• I a
•
• I u
•
~
• • d
• •
"• •
•
J13
I r-~~ ............... ....-n-~~~~~---~~~~~~~~~~~~--ril'"TT..,.,.. ...... ~~-.
I
002
G13 I
L-------__J
EDS Positions
Substrate
Pin Side (Viewed from Rear of K.B.)
*Can have up to 88 positions
Note 1 Some models do not have two connectors-Connector 1 will always be In the tame location
Figure 1-12. Encode Board (Old Style)
1-8 (3/71)

Inputs {
from
EDS
Switches
Shift (Upper or Lower Case}
A
*Note: Some Models Use Diode Matrix in Place of SLD Logic
Figure 1-13. Encode Circuits (Example)
Bit Latch
FL
2 Bit
4 Bit
Figure 1-14. Restore Bail Interposer and Latch Key Interposer Comparison
Bail Drive Card
A SMS drive card, mounted below the keyboard, is used to
drive the restore bail magnets. It is con~rolled by the using
system. The using system prevents the flow of current
through the magnets which restores the keyboard during
operation or locks the keyboard when not in use.
Shift Key
The SHIFT key shifts the keyboard into uppercase, causing
the character key output to be coded differently. The
shift key operates the same as any momentary key. The
SHIFT key is not interlocked because other keys must be
operated with it.
Some models have a SHIFT key LOCK (Figure 1-15) that
allows continuous uppercase operation. When the LOCK
key is pressed, the turned-over ear pivots the latch against
the lock bar. Additional pressure causes the keylever to Figure 1-15. Shift Key Lock Mechanism
(Data Available)
Restore Bail
Latch Key lnterp~ser
Shift Key
Elastic Diaphragm Enc Kybds and 5475 Data Entry Kybd (3/71) 1-9

pivot down and the latch to slide along the lock bar. As
the latching surface of the latch passes the lock bar, it pivots
under the lock bar and latches in this position as pressure is
released on the LOCK key. To release the lock, the SHIFT
key is pressed. The latch moves free of the lock bar and
returns to its normal position under spring tension.
The binary counter, driven by a free running oscillator,
generates counts to scan the horizontal and vertical lines of
the switch matrix. When the scan coincides with a switch
closure, the data selector generates 'scan complete', which
stops the counter. The output of each ROS address (counter
output) is stored in a 4-bit register. When 'scan co~plete'
occurs, the bits stored in the register (A, B, C, and D) from
the previous ROS address and the bits from the present
ROS address (1, 2, 4, and 8) make up the 8 bits of the
character. 'Scan complete' also brings up 'any data', which
tells the using system that data.is on the 'bit' lines. A 'reset'
line is generated to reset the counter.
Invalid characters are detected before the set of 'any
data'. 'Any data' is timed to ensure valid data on the data
bus; and timing ensures that 'scan complete' is ignored,
during count transitions, to prevent false addressing.
New Encode Circuit Board and Switch Assembly
Some models of the keyboard have a redesigned encode
board and switch assembly (Figure 1-16). This board is
mounted on the rear of the keyboard instead of on the top,
and does not have a flexible substrate. The components of
the new board are the substrate, separator, diaphragm,
switch spacer, and latch assembly. Operation of the switch
assembly is the same as with the old board.
The encode board portion of the assembly uses T2L
logic in place of SLD logic, and has a different theory to
produce the same output lines (Figure 1-17). A ROS (read
1-10 (3/71)
...._~----v-~~~~~--'
Note 2
Notes:
1• The Latch Spring Assembly provides the combined functions
of the Activator and Latch Springs of the previous design.
2. The Logic Card and Switch are Factory-Assembled and to
be replaced as a unit.
Figure 1-16. Redesigned Encode Board and Switch Assembly
only storage) unit, programmed for the proper output code,
is used instead of the 'bit' latches, and is addressed for each
switch position. A switch matrix, a seven-bit binary counter,
and a data selector generate the ROS address and take the
place of the AND/OR circuits used to set 'bit' latches.

Counter
~~c~o_u_n_t_l ___ --1-r--r------------lr-------i
Count 2
.-----i~ Clo~
Reset
Tl
---~N
i
Count 4 Spec
Count 8
Count 16
Count 32
Switch M1-at-r-ix- ... -----~------------ ... -=--=--=-~-=-~-1~·1--S-ca_n_C I ... ~ .... , p_l_e_te _ ___,
- 1~~ r , " ~
>I ~ "? .-------1 Bit D
+-t-t--+-- 1----+-~-1-+-<~+-!4.-'4~+"4'!: 4-7 J R
Spec >I< ~ >I< I< >I > ~
>i~> !<~>+< &
>+< >i )'- >+<>+< ~ • R Bit C
...______. "r' 7 lo.I '"" '""'
'--~~~~1-+-+-Hl-f---IEl-----f:-i-·~G_a_te~-+--+--~---a~] R
~1----------' J -
R
Bit B
Bit A
Shift
~ROS Bitl
-------1 256X4 -----Bi-t-
2
Bit 4
Bit 8
Error
Scan Complete A
1-----------11~1------A_n_y_D_a_ta_(D_a_t_a_A_v_a_il_a_b_le_)
------iN._ _____ ___.
Delayed Bail Forward
Figure 1-17. Encode Circuits (New Style Encode Board)
Elastic Diaphragm Enc Kybds and 5475 Data Entry Kybd (3/71) 1-11

PREVENTIVE MAINTENANCE
CAUTION
Remove power before performing PM or removing
keyboard.
Perform preventive maintenance to the keyboard during
unscheduled interruptions when possible. If unscheduled
interruptions do not occur in a twelve month period, a
preventive maintenance schedule must be provided. The
keyboard can be removed from its mounting (remove
power first) for easy servicing. Cable connections on the
left and right sides of the keyboard, and plug-on connectors
for the drive card, make removal easy.
Lubrication
Always lubricate with number 23 grease.. Grease the
following points every twelve months:
• Keylevcr pivots
• Keylever leaf and return springs
• Front interposer guide combs
• Space bar shaft pivots and keylever tab
• Dobber pivots
• Space bar pivots
• Restore bail armature pivots
• Reset drive spring anchors
• Latch spring and momentary link connections
• Interposer latch spring tips
• Shift bar shaft pivots
Cleaning
Clean the unit before each lubri~ation and when the environ-
ment indicates it is necessary.
MAINTENANCE
CAUTION
In localing troubles in the circuit portion of the keyboard,
do not use a test light; it could cause damage to the
circuits. Also when using an ohmmeter, take care to
prevent shorting pins or overloading the circuits. Do
not use the ohmmeter on less than R X 100.0 scale.
Part 2. Maintenance
Maintenance consists of adjusting mechanical parts and
replacing worn parts. When troubles are in the encode
board or the magnet driver card, these items must be
replaced. Trouble with the EDS may require replacing
the separator and the diaphragm, or adjusting or replacing
the actuator or the latch spring.
Test points for troubleshooting EDS switches and the
encode board are in the keyboard logics for the using
system.
CHECKS, ADJUSTMENTS, AND REMOVALS
Key Lever
Checks
The keylever, when pressed, should move around its pivot
at the rear of the keyboard until the lever bottoms in the
front guide comb. When released, it should rise until the
lever strikes the upstop rod in the front comb (Figure 2-1 ).
The <lobber should clear the interposer and should return
to its rest position above the interposer projection when
the key is released.
Note: Unused key positions require their elastic
diaphragm switches to be either open or closed. If
the switches are to be held open, the keylevers are
blocked by a plastic lockout (Part 5994922) to prevent
the operation of the interposer. Closed switches do not
have interposers and are held closed continuously by
the latch spring assembly.
Adjustment
There is no keylever adjustment to meet keylever travel
called for in the checks. Failure to meet these conditions
indicates some defect in the keylever operation or with
the associated mechanisms. Refer to the diagnostic
flowchart in Appendix A or the diagnostic flowchart for
the specific system. For <lobber clearance, refer to
"Adjustment-Latch Key".
Removal
1. Loosen the two front and the two rear encode board
mounting screws, and tilt the board to the rear of the
keyboard (old style only).
2. Remove keybutton from the keylever that is to be
replaced.
3. Remove other keybuttons that extend over the
keylever that is to be replaced.
Elastic Diaphragm Enc Kybds and 5475 Data Entry Kybd (3/71) 2-1

Front Guide Comb
Figure 2-1. Latch Key Adjustments
4. Pull out the pivot rod with pliers or use a follower rod
to push it out until the keylever is free.
5. Raise the pivot end of the keylever to be removed and
work it to the rear until it clears the upstop rod. Work
the keylever out of the keyboard.
6. Replace in the reverse order.
7. Perform checks and necessary adjustments.
Interposer
Checks
The interposer should be latched by the EDS latch spring
before the downward motion of the keylever is complete.
When the keylever hits its downstop, the interposer should
have some travel left before it bottoms on the guide comb
slot at the rear of the keyboard.
Adjustment-Latch Key
The interposer tip must clear the EDS latch spring, and must
be at least 0.005 inch above the bottom of the interposer
guide comb slot (Figure 2-2) when the keylever is fully
operated. To obtain these conditions, the keylever must be
formed. If the interposer is not traveling far enough, form
the keylever (Figure 2-3) by placing pliers across the pro-
jections provided on the keylever. Squeeze gently to obtain
the desired position of the <lobber. If the interposer is
traveling too far, form the keylever (Figure 2-4) by placing
2-2 (3/71)
Rear Interposer
Guide Comb
Restore Bail
Latch Spring
f
0.005 Minimum Gap
Figure 2-2. Interposer to Guide Comb Clearance
pliers on one projection and a screwdriver between the
projections then spreading the projections. Hold the screw-
driver tip against the pliers and the shank against the
opposite projection applying force to spread the projections.
The theory of this adjustment is to raise or lower the
tail of the keylever, thus changing the relative position of
the <lobber. The travel of the keylever is not affected. If
the tail is raised, it will strike the upstop sooner and the
<lobber will be lower and closer to the interposer. The
opposite is true if the tail is lower; it will strike the upstop
later and the <lobber will be further from the interposer.

Needle-Nose Pliers
{or Duck Bills)
Figure 2-3. Dobber Adjustment (To Lower Dobber)
Keylever
Needle-Nose Pliers
(or Duck Bills)
Screwdriver
Keylever
Figure 2-4. Dobber Adjustment (To Raise Dobber)
Adjustment-Momentary Key
Momentary key interposers must travel at least 0.025 inch
before the switch closes, and must have a minimum over-
travel of 0.005 inch. The keylever is to be adjusted to
.obtain these dimensions, and it may be necessary to form
the momentary link to obtain the proper overtravel
(Figure 2-5).
Removal
1. Loosen the front and rear encode board screws and tilt
the encode board up and to the rear of the keyboard
(old style only).
2. Remove the keylever upstop rod.
3. Remove the spacebar rod.
4. Raise the keylevers evenly.
5. Pull out the interposer pivot rod with pliers or push it
out with a follower rod.
6. Remove the spring from the interposer to be removed.
7. Raise the pivot end of the interposer and remove to the
front of the keyboard.
8. Replace in the reverse order.
9. Perform checks and necessary adjustments.
Interposer Return Spring
Interposer
Figure 2-5. Momentary Key Interposer Overtravel
Restore Bail and Magnet Assembly
Checks
Latch Spring
Link
(Form for
Overtravel)
The bail should clear the restored interposers when it passes
beneath them. The interposers should clear the bail when
they are latched and should be restored fully when the
magnets are not energized.
CAUTION
Magnet yoke nuts are not to be tightened more than
finger tight plus 1/4 turn.
Adjustments
Each bail spring should require 130 to 170 grams of force
to pull its end of the bail away from the stop with the
magnet not energized. The top surface of the bail (Figure
2-6) should be 0.015 inch± 0.014 inch below the inter- 1
posers when the magnets are energized. There is no adjust-
ment for the top surface of the bail other than the play in
the yoke mounting holes. The restore surface of the bail
should be 0.015 to 0.030 inch from the restore surface of
the interposer with the magnets energized. Adjust the
restore surface clearance by positioning the magnet yoke
assemblies within the side frames. It may be necessary to
form the feeler gage to make this adjustment as the magnet
yoke interferes with the gage.
Adjust the bail stops to allow proper restoring of the
interposers. Place a 0.020 inch shim between the bail and
the bail stop (Figure 2-7). When the bail is operated, the
interposers should restore. The interposers should not
restore with a 0.030 inch shim between the bail and the
bail stop.
Elastic Diaphragm Enc Kybds and 5475 Data Entry Kybd (3/71) 2-3