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

141
KEYBOARD POR MINI-MAP
Tools
• Use this mini-MAP to locate an open or grounded
'-power-on reset' (POR) line.
Connect the CE probe as follows:
• +lead-1-G-D03
• For mini-MAP example, see Troubleshooting Aids
(212).
• -lead-1-G-D08
• Ground-1-8-D08
Conditions After Power On
The' -power-on reset' line is at an Up level.
Service Aids
• The' -power-on reset' line is at a Down level for
about 0.5 seconds during power on.
• The display station will not be damaged if it is
powered on after the keyboard cable has been
disconnected.
Planar
Board
I nterposer I I nternal I
I
Keyboard
I
I I
Cable
I
I '
13
I
,
~~~
,
~ ~
0
1 25
I
Keyboard
Signal
Cable
B02
1-66
Keyboard Logic
Printed Circuit
Board
--1-
--m-
--h::
~rt11 ~
I
±-==
I ::
~TJ-·······::::::-~If1c:::r:.~
-~-~~
- , , \ 14
I
I
7\
I
D02
I
Clean both sides
I
B02
I
B02
I I
of the pad
I
002
I
I
I
printed circuit
I
I
I
I
board connector
I I I
contacts (130).
I
I
!
I
I '
Ac!ess
I l L +
5V
Panel
-Power-On Reset
I
1-B-D07
I
17 007
~~--~»~------------~~~~------------~~
Driver
I I I I