IBM 6500-V05 Maintenance Manual - Page 255

IMPORTANT When making continuity checks, touch the meter leads to the test points for at least 2 - 3 seconds so that your meter will have time to display correctly. 7. At one end of the cable, touch one of the pins with the positive (usually red) meter lead while the common lead (usually black) is still touching a ground point. 8. Check the pin for a short to ground, which is indicated by a meter reading of continuity (that is, a low resistance reading of less than 1 Ohm). 9. If you find a short to ground, replace the cable. If no short is detected, repeat steps 7 and 8 for the rest of the pins on the same end of the cable. If no shorts to ground are detected for any of the pins, proceed to the next section, which checks for pin-to-pin shorts. Check for pin-to-pin shorts: 10. Disconnect the common (usually black) meter lead from the ground point. 11. Check for shorts within the cable by touching the common meter lead to pin 1 at one end of the cable and touching the positive (usually red) meter lead to pin 2 at the same end of the cable. 12. Check for a pin-to-pin short, which is indicated by a meter reading of continuity (that is, a low resistance of less than 1 Ohm). For a properly functioning cable that has no pin-to-pin short, you will see the "open circuit" meter reading you recorded in step 4. 13. If you find a short, replace the cable. If no short is detected, check for pin-to-pin shorts on all the remaining pairs on the same end of the cable. If no shorts are detected for any of the remaining pairs, return to the procedure that referred you to this diagnostic procedure. 255