IBM 5251 Series Maintenance Information Manual page 53

121
(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.
- Power off.
- Disable the MSR feature if it is installed (119).
- Power on.
- Check the +12 Vdc at 2- F- 012.
- The +12 Vdc should be between 11.8 Vdc and 13.3
Vdc.
Is the voltage in tolerance?
Y N
- Check the '+12 Vdc' at JOl-5 cable connector on
the light pen card.
Is the voltage in tolerance?
Y 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 card (125).
- Check the +5 Vdc line at 2-E-D03.
Is the voltage correct?
Y N
A
Inspect the interposer.
- Replace the planar; set the jumpers correctly on
the new planar (103) (105).
A
I
Probe the '-LP photocell' line at 2-F-D13.
Is the line at an Up level?
Y N
- Power off.
- Disconnect the light pen cable.
- Power on.
- Probe the '-LP photocell' line at 2-F-D13.
Is the line at a Down level?
Y N
- I nspect the interposer.
- Replace the light pen card (125).
- Replace the light pen assembly (125).
Is the problem invalid (unrecognizable) characters on
the display screen?
Y N
- Probe the following lines on the interposer at the
1 E socket of the planar:
Line Name Pin Level
-reg 13 bit 0 004 Down
-reg 13 bit 1 005 Up
-reg 13 bit 2 007 Up
-reg 13 bit 4 009 Up
-reg 13 bit 5 010 Up
-reg 13 bit 3 011 Down
-reg 13 bit 6 012 Up
-reg 13 bit 7 013 Down
Are all of the lines at the level as shown above?
Y N
BCD
Maintenance Procedures 5251 MIM 1-35