IBM 5251 Series Maintenance Information Manual page 61

123
(continued)
-Probe the '-reg 5 bit l' line
at 2-E-1303.
Is any probe I ight On?
Y N
-Inspect the interposer.
-Replace the planar; set the
jumpers correctly on the new
planar (103)( 105).
-Check the ground at 2-F-DOB.
Is the ground OK?
Y N
-Inspect the interposer.
-Replace the light pen feature
card (125).
-Use a CE meter to check the
operation of the tip switch.
Does the tip switch operate correctly?
Y N
-Replace the I ight pen feature
assembly (125).
-Inspect the interposer.
-Replace the light pen feature
card (125).
Suggested action for an intermittent
problem:
• Analyze the suspected line; inspect
all of the connector contacts.
• Replacement sequence:
-Light pen feature card
-Light pen feature assembly
-Light pen power supply card
-Planar
Maintenance Procedures 5251 MIM 143