(3) Disconnect the power cable from pins 1 and 2 at terminal board TB1.
(4) Check for continuity between the ends of the power cable. Replace the control unit cover
and secure with 16 screws and washers.
d. Light box.
(1) The light box consists of switches wired to the lamps in a series-parallel configuration. A
malfunction can be sectionalized by operating the front panel switches, observing the lamps that light, and
then performing a continuity check of the wires that connect the switch to the defective lamp(s).
(2) If all the lamps are inoperative and the print power indicator is extinguished, the OFF-
TIMER switch is defective.
(3) If all the lamps are inoperative and the print power indicator is lighted, the PRINT LIGHTS
switch is defective.
(4) If a group of lamps are inoperative, the associated pattern switch is defective.
(5) Each print lamp has its own switch which should be checked individually for operation.
Repairs and replacement of parts.
a. The following contains the replacement procedures for components replaceable at the
organizational level. Most of the replaceable parts can be easily reached and replaced without special
procedures. Perform the disassembly procedures indicated only as far as necessary to remove the defective
component. Group all parts together in the order that they are removed.
b. Decade switch replacement.
(1) Remove screws (4, fig. 2-5), washers (5), lockwashers (6), nuts (7), and decade switch (1 or
(2) Remove the plug from the decade switch jack.
(3) Attach the plug to the new decade switch.
(4) Secure the decade switch (1 or 2) with the screws (4), washers (5), lockwashers (6), and nuts