Keyboard Scan Code Mini-Map; Conditions After Power On; Service Aids; Tools - IBM 5251 Series Maintenance Information Manual

137
KEYBOARD SCAN CODE MINI-MAP
• Use this mini- MAP to locate an open or grounded
scan code line.
• For mini-MAP example, see Troub/eshootingAids
(212).
Conditions After Power On
The scan code lines are valid after a key has been
pressed.
Service Aids
• All scan code lines are switched Up and Down when
you press a keyboard key. A 1 is displayed in the
scan code field on the display screen when a line is
active.
• Use the Shift key to test the ' - break code' line. The
break code position in the displayed field is normally
O. The position changes to 1 only after the Shift key
has been pressed and released.
Planar
Board
I nterposer I
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Internal
Keyboard
Cable
1-54·
• The display station will not be damaged if it is
powered on after the keyboard cable has been
disconnected.
Tools
Connect the CE probe as follows:
• +lead-1-G-D03
• -lead-1-G-D08
• Ground-1-B-D08
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13
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1
Display Screen
Status switch in the
Test position; keyboard
key pressed
Keyboard
Signal
Cable
Keyboard Logic
Printed Circuit
Board
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±-=.::
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--I---m---f-i::
0
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.........
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~.j!!!!II!I!!liIH~-~~·
..
r-~c:::r,.-=:;~,.,-
25
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-1-71~ T~~2
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B02
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-Break Code Bit 0
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-Scan Code Bit 1 ,
-Scan Code Bit 2
-Scan Code Bit 31
-Scan Code Bit 41
-Scan Code Bit 5
-Scan Code Bit 61
-Scan Code Bit 7 J
+5V
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002 B02
l-B-B 12
1-B-B05
l-B-006
1-B-013
1-B-B08
l-B-B09
l-B-Bl0
1-B-B13
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--===b_
Clean both sides
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of the pad
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printed circuit
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board connector
contacts (130).
A~~
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Panel
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8 B12
3 B05
16 006
22 013
5 B08
6 BOO
7
B10
9 B13
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t
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»
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~--~~>-----------------~»~--------------~~~
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Driver