Service Aids; Tools - IBM 5251 Series Maintenance Information Manual

122
LIGHT PEN REGISTER AND CONTROL
MINI-MAP
• Use this mini-MAP to correct a light pen problem
when the cursor does not follow the light pen or
when the light pen blanks data on the display screen.
• For mini- MAP example, see Troubleshooting Aids
(212).
Conditions After Power On
• The '-reg 13 bit 2' line should be at an Up level.
• The' -reg 5 bit' lines should be Up except' -reg 5 bit
6', which should be Down.
• The '1.0 MHz', '-horiz blank', and '+LNC' lines
should be pulsing.
Service Aids
• The' -reg 13 bit 2' line should pulse when the light
pen is being used.
• The display station will not be damaged if it is
powered on after the keyboard, MSR, or light pen
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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Maintenance Procedures 5251 M
1M
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