Tektronix Phaser 840, Service Manual

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84 Phaser 840 and 850 Color Printers
7.
Ensure that the cap/wipe/purge heater is operational. Verify that the heater
resistance is about 350 ohms (+/- 50). Inspect inside the cap for ink build up;
a lot of built up ink inside the cap indicates that the heater is not melting it
out. The ink built up interferes with the wiper compressing, and can prevent
the cap/wipe/purge assembly from sealing on the printhead.
8. Another way to evaluate a cap/wipe/purge assembly gasket leak is to
examine the distribution of ink in an empty waste bin following a purge
cycle. When the system is sealing properly, a purge cycle produces
approximately 18 mm (3/4 in.) of ink across the waste tray.
If the vacuum system suffered from low vacuum, either caused by a
poorly-sealed gasket, a failing vacuum pump or a clogged vacuum
tube, then you will see significantly less waste ink in the waste tray.
Maintenance tray showing good purge