IBM 5251 Series Maintenance Information Manual page 57

122
(continued)
- Check for proper positioning of the jumper on the
card (124).
Is the card jumpered correctly?
Y N
Set the jumper correctly.
- Verify correct operation.
- Probe the '-reg 13 bit 2' line at 1-E-D07.
Is the line at an Up level?
Y N
- Inspect the interposer.
- Replace the planar; set the jumpers correctly on
the new planar (103) (105).
- Probe the '-horiz blank' line at 2-F-B07 and the
'+LNC' line at 2-F-BOB.
Are both lines pulsing?
Y N
- Power off.
Disconnect the 2J cable at the 2F interposer.
- Power on.
- Probe the failing line at the 2F interposer.
Is any light On?
Y N
Inspect the interposer.
Replace the light pen feature card (125).
Is the Down light On?
Y N
- Probe the failing line at the 1 J interposer.
Is the line pulsing?
Y N
- Power off . .
- Disconnect the 2J cable at the planar
interposer.
- Power on.
Probe the failing line at the J interposer.
Is the line pulsing?
Y N
I I
ABCDE
ABC
D1
Inspect the interposer.
- Replace the planar; set the jumpers
correctly on the new planar (103) (105).
- Replace the 2J cable.
- Replace the 2J cable.
- Inspect the interposer.
- Replace the light pen feature card (125).
- Power off.
- Wait five seconds.
- Power on.
Probe the following lines. Record any lines that are
not at the level shown.
Press the left shift key for each line. Do not press
any other keys.
Line Name Pin Level
-reg 5 bit 1 1-E-B03 Down light pulses
-reg 5 bit 0 1-E-B05 Down light pulses
-reg 5 bit 2 1-E-B07 Up
-reg 5 bit 5 1-E-BOB Down light pulses
-reg 5 bit 3
1-E-B09
Down light pulses
-reg 5 bit 4 1-E-B10 Up
-reg 5 bit 6
1-E-B12
Down light pulses
-reg 5 bit 7 1-E-B13 Down light pulses
Are all the lines at the level shown above?
Y N
Power off.
Disconnect the light pen feature card by
unplugging the interposer at connector 1 E and
plugging it into the planar connector only.
- Power on.
Probe the failing line on the interposer.
Is the line at the correct level?
Y N
F G
Inspect the interposer.
- Replace the planar; set the jumpers correctly on
the new planar (103) (105).
Maintenance Procedures 5251 MIM 1-39