Radio Shack TRS-80 Service Manual page 63

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Phenomen
- 8- Y-direction
mo.,·cmcnt is
insufficie nt ~
Condition
2
Paper and rubber roller
slip.
I Character alignment on
one line is bad, and the
lino rises at the rtght end.
2 Stepping error in
Y-dlrectlon.
Cause
6 Paper holding roller
support plate unit (left)
(34) does not operate
smoolhly.
7
Paper holding roller
support plate unit
(right) (3-5) does not
operate smoolhly.
I
Damage to paper holding
rollor (large) (3-6) and
r,•pe~~d~groller
small 3-7 .
2 Defonnation of paper
guide.
3
Foreign matter in paper
guide.
I
Roll paper load
i$
too
heavy.
I
Y drive n1cchanisn11 gear
is damaged.
2 Sliding paper feed gear,
by one tooth, gearing of
rubber roller unit is
not enough.
3
Rubber roller unit
bearing is worn.
Location and Method
of Checking
Hook tweezer tips in hole of
spring hook on paper holding
roller support plate unit and
move it up and down.
Hook tweezer tips in hole of
spring hook on paper holding
roller support plate unit and
mO\'e
it
up and
down.
Check if paper holding roller
is there.
Check for paper quide
defonnation.
Check for foreign matter
in
paper guide and for insertion
of paper.
Check that roll paper is guided
smoothly ir> to the printer.
Check Y-gcar idle (3·2), rubber
roller urtit (3-3) gear, and
Y-rnotor unit (3·1 l gear.
Check that the two·picce tooth
gc-ar on rubber roller uni1 is
engaging after being slid by one
tooth.
Move rubber roller unit gear up
and down by hand and check
for play.
Repair Method
Replace paper holding roller
support plate unit (left).
Replace (>3per holding roller
support plate unit (right).
Mou. n t dtmaged roller.
Replace printer.
Remove foreign maner.
Repair roll paper guide.
Replace gears.
Mount after setting ii properly.
• Replace rubber roller unit
if wear is noticed.
• Fix by using a cyanoacrylate
adhesive when there is play
be1wcen 1he bearing and
frame.
• Replace printer'.
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