IBM 5251 Series Maintenance Information Manual page 29

111
(continued)
Check the voltages and grounds.
l-H-Bll (+8.5V)
l-H-B08 (GNO) or down light on probe
l-H-008 (GNO) or down light on probe
l-H-003 (+5V)
Are the conditions normal?
Y N
- Inspect the interposer.
Replace the planar.
- Power off.
- Select the failing circuit (see above).
Remove the cable at the planar.
Using an ohmmeter, measure the resistance of the
selected circuit at the cable.
Are the conditions normal?
Y N
Trace the conditions to the component (see
above).
Repair or replace the cable or replace the
component.
Check the circuit for grounds in the cable.
Were there any grounds at the cable?
Y N
Verify that the address switches are set correctly.
Inspect the interposer.
Check the jumpers and replace the planar.
Trace the ground on the component (see circuit).
Repair or replace the cable.
Replace the component.
Suggested action for an intermittent problem:
• Analyze the suspected line; inspect all the connector
contacts.
• Replacement sequence:
- Component
Planar
Control panel cable
Maintenance Procedures 5251 MIM 1-11