Inspecting The Power Supply Fuses - Tektronix PHASER 840 Service Manual

Inspecting the power supply fuses

Three fuses (F1 - F3) are mounted on the power supply.
1.
Turn off the printer and remove the power cord.
2.
Remove the screws securing the power supply. Disconnect the wiring
harnesses plugged into the right side of the power supply and remove
power supply.
3.
With a DMM, determine that the fuses on the power
supply are functional. Measure the resistance of all fuses to LINE as
indicated on the power supply's shield.
If any fuse opens, the power supply does not function and should be
replaced.
Caution
Fuses F2 and F3 are used for the AC heaters within the printer; they
protect the power supply from, most often, a shorted triac. If F2 or F3
blows, replace the power supply rather than the fuse. Otherwise, with the
fuse replaced, but the triac shorted, AC power may be applied to the heater
without the printer even being turned on, resulting in a thermal runaway
condition.
Fuse F1 is for the DC power supply, all DC outputs.
Fuse F2 is for the following heaters:
H3 Jet Stack Left
H4 Paper PreHeat
H10 Jet Stack Right
H11 Reservoir #2
H12 Drum #2
H14 Reservoir #4
If the fuses are functional, but the printer's power supply does not output DC
voltages, proceed to the topic, "Testing for shorted drivers" on page 62.
Fuse F3 is for the following heaters:
H1 Drum #1
H2 Reservoir #1
H5 Black Ink Melt
H6 Magenta Ink Melt
H7 Cyan Ink Melt
H8 Yellow Ink Melt
H9 Cap Wipe Heat
H13 Reservoir #3
Service Guide
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