Keyboard Voltage And Strobe Mini Map; Conditions After Power On; Service Aids; Tools - IBM 5251 11 Maintenance Information Manual

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138
KEYBOARD VOLTAGE AND STROBE MINI MAP
• Use this figure to correct a data strobe or strobe
delay problem.
• A failure in the '-5 Vdc', '+5 Vdc', '-data strobe', or
'+delay strobe' line causes both the' -data strobe'
and '+delay strobe' lines to fail.
• For Mini MAP example, see Troubleshooting Aids (212).
• The display station will not be damaged if
. powered-on after the keyboard cable is
disconnected.
Conditions after Power-On
• The voltage lines are active.
Tools
• The' -data strobe' line is positive (+) (the pulse will
be negative when a key is pressed).
Connect the CE probe as follows:
• The' +delay strobe' line is negative (-) (the pulse will
be positive when a key is pressed.)
Service Aids
• When a key is pressed, the' -data strobe' line pulses
at a Down level.
• When the planar receives the' -data strobe' line, it
pulses the '+delay strobe' line at an Up level.
Planar
80ard
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I nterposer I
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I I
Internal
Keyboard
Cable
• +lead-l-G-D03
• -lead-l-G-D08
• Ground-1-B-D08
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13
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Keyboard
Signal
Cable
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Connector 8
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-1-
_1-
--f-i: :
0
, ±-::::::
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~~~
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n
-1~7 -~:\
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B02 ' \
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002
~~~~#,~]:c=?,.~
1 25
f
14
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002
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802
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Access
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Panel
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1-8-806
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13 806
-5 Vdc
+5 Vdc 1-8-003 25 003
Ground
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1-8-008
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23~24 0~8
Keyboard Logic
Printed Circuit
80ard
Clean both sides
of the pad
printed circuit
board connector
contacts (130).
----------~« »~----------------~»~----------------------------~»>-------------
+5V
I I I I
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_-0_a_ta_S_t_ro_be~~~k
__
1-_8_-8_0_7_~~~>
_______________________
~~~>--------------------~~~
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I t t
+5V Driver
I I
I 1
~
I 2' 0
0'11
~,
1-8-011
»>-----------~»">------------4).;'>-~---
Driver
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