IBM 5150 Hardware Maintenance Manual page 163

Error
Description
Diagnostic Action
Extra
Print
Dots
l.
Run Offline Diagnostic Test (see page
1400-33). Examine the / and V-characters
for extra dots.
2. Remove CN6 on Driver Circuit card (see
Section 5, "Locations"). Measure
approximately 22 ohms between pin
CN6-10 (male side) and each head coil pin
(CN6-1 to 9 - male side).
Resistance
=
22 ohms?
YES:
Replace both Control cards (see
Section 3, "Removal/Replacement").
NO:
Disconnect print head cable and
check pins I through 9 (see Section
5, "Locations") for approximately
22 ohms.
Resistance
=
22 ohms?
YES:
Replace Print Mechanism
assembly (see Section 3,
"Removal/Replacement").
NO: Replace print head (see Section
3, "Removal/Replacement").
1400-22