IBM 5150 Hardware Maintenance Manual page 161

Error
Description
Diagnostic Action
Row(s) of
1. Check ribbon for damage (folds, holes,
Print Dots
tears). Replace cartridge if damaged.
Missing
2. Verify print head gap adjustment is between
0.6 to 0.65 mm (0.024 to 0.026 in.) at
center position of adjusting lever. (See
Section 3, "Removal/Replacement.")
3. Check for damaged platen. Replace print
mechanism if platen is damaged. (See
Section 3, "Removal/Replacement.")
4. Check print head for broken wires. If wires
are broken, replace print head. (See Section
3, "Removal/Replacement.")
5. 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 on print head
cable for approximately 22 ohms in
respect to common. (See Section 5,
"Locations.")
Resistance
=
22 ohms?
YES: Replace Print Mechanism
assembly (see Section 3,
"Removal/Replacement").
NO: Replace print head (see Section
3, "Removal/Replacement").
1400-20