IBM 5251 Series Maintenance Information Manual page 81

139
(continued)
Check the clicker coil and the '+8.5 Vdc' line as
follows.
- Remove the lower coil wire.
Does the clicker sound each time the wire is
touched to a ground pin?
Y N
- Check for +8.5 Vdc at the upper clicker pin.
Is the voltage correct?
Y N
- Check for an open '+8.5 Vdc' line back to the
planar.
- Replace the clicker.
- Check the '-clicker activate' line (803) at the planar.
Note: When no key is pressed, the line should be at an
Up level. If the line is not at an Up level, answer no to
the next question.
Does the line pulse each time a key is pressed?
Y N
Is the line at a Down level?
Y N
Does the line (B03) pulse each time a key is
pressed?
Y N
Inspect the interposer.
Replace the planar; set the jumpers correctly
on the new planar (103) (105).
Check the cable for an open.
Check the' -clicker activate' line for a ground.
Check the keyboard end of the cable.
- Replace the logic PC board.
139
Suggested action for an intermittent problem:
• Analyze the suspected line; inspect all the connector
contacts.
• Replacement sequence:
- Keyboard logic PC board
Planar
- Keyboard cables
Maintenance Procedures 5251 M 1M 1-63