IBM 5251 Series Maintenance Information Manual page 49

120
(continued)
- Check for proper positioning of the jumper on the
card (124).
Is the card jumpered correctly?
V N
- Set the jumper correctly.
- Verify correct operation.
- Check the '+12 Vdc' line at 2FD12. The line should
be between +11.8 Vdc and +13.3 Vdc.
- Check the' -6 Vdc' line at 2FD06. The line should be
between -5.9 Vdc and -6.6 Vdc.
Are the voltages in tolerance?
V N
- Check the '+12 Vdc' at J01-5 and the' -6 Vdc' at
J01-3 on the light pen feature card.
Are the voltages within limits?
V N
- Check the cable to the light pen power supply
card.
- Replace the light pen power supply card.
- Inspect the 2F interposer.
- Replace the light pen feature card (125).
- Check the '+5 Vdc' line at 2-J-D03.
Is the voltage correct?
V N
- Inspect the interposer for an open.
- Replace the planar; set the jumpers correctly on
the new planar (103) (105).
- Probe the '-POR' line at 2-E-804.
Is the line at an Up level?
V N
- Inspect the interposer for an open.
- Replace the planar; set the jumpers correctly on
the new planar (103) (105).
A
A
1
Probe the following lines on the interposer at the 2F
socket of the planar.
Line Name Pin Level
-end of row 802 Pulsing
-horiz blank 807 Pulsing
+LNC 808 Pulsing
-vertical blank 812 Pulsing
Are all of the lines pulsing?
V N
B
- Power off.
- Disconnect the 2J cable at the 2F interposer.
- Power on
- Probe the failing line at the 2F interposer.
Is any light on?
V N
- Inspect the interposer.
- Replace the light pen feature card (125).
Is the Down light on?
V N
- Probe the failing line at the 1 J interposer.
Is the line pulsing?
V N
- Power off.
- Disconnect the 2J cable at the planar
interposer.
- Power on.
- Probe the failing line on the J interposer.
Is the line pulsing?
Y N
- 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).
Maintenance Procedures 5251 MIM 1-31