Tektronix Phaser 840, Service Manual

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120 Phaser 840 and 850 Color Printers
Inspection
Rollers: Replace the rollers when you see any of the following defects:
■
Flat spots.
■
Out of roundness.
■ Cracked rubber.
■
Loss of traction (tackiness) causing pick or feed failures.
Gears: Replace gears that show any signs of wear or breakage. Look for these
problems:
■
Thinned gear teeth.
■
Bent or missing gear teeth; check especially where a metal gear drives a
plastic gear.
■
Fractured or cracked gears. (Oil or incorrect grease on a plastic gear can
cause the gear to crack.)
Belts: Inspect the belts for wear. There are eight rubber belts in the printer:
■
A belt from the process motor to the compound gear
■
Two belts from the y-axis motor drive
■
A belt from the lower paper-feed roller to the upper paper-feed roller
■
Two belts on the cap/wipe/purge drive
■ An exit-roller drive belt
■
A small belt for driving the cap/wipe purge assembly from the cap/
wipe/purge clutch
Look for these problems:
■
Loose rubber particles below the belts indicate a worn belt.
■
Missing teeth in the belts.
■
Cracking or moderate fraying; a small amount of fraying is inevitable,
so look for other signs of wear before replacing the belt.
Clutches: There are four clutches: the paper-pick roller clutch, the upper-feed-
roller clutch, the maintenance drawer cam clutch and the cap/wipe/purge clutch.
Symptoms of a malfunctioning clutch are the printer not picking paper from the
tray or other paper jams. Also the cap/wipe/purge system could fail. In such
cases, replace the clutch. Intermittent jams are often caused by failing clutches.