IBM PCjr Hardware Maintenance And Service page 250

Error
Description
Diagnostic Action
Random
1. Check ribbon for damage (folds, holes,
Print Dots
tears). Replace if damaged.
Missing
2. Verify print head gap adjustment is between
0.6 to 0.65 mm (.024 to .026") at center
position of adjusting lever. See Section 4,
"Removal/Replacement and Adjustments."
3. Check for damaged platen. Replace print
mechanism if platen is damaged. See Section
4, "Removal/ Replacement and
Adjustments."
4. Check print head for broken wires. If wires
are broken, replace print head. See Section
4, "Removal/Replacement and
Adjustments."
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]).
Does the resistance = 22 ohms?
YES: Replace both control cards. See
Section 4, "Removal/Replacement
and Adjustments."
NO: Disconnect print head cable and
check pins 1 through 9 on print head
cable for approximately 22 ohms in
respect to common. See Section 5,
"Locations."
Does the resistance = 22 ohms?
YES: Replace print mechanism
assembly. See Section 4,
"Removal/ Replacement and
Adjustments."
NO: Replace print head. See Section
4, "Removal/Replacement and
Adjustments."
3-1400-20 Graphics Printer