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Raw power supply voltages can be measured at the
point where they are cabled to the digital board from
the power supply. Regulators on the digital board re-
duce the power supply +6VDC level to +5VDC. This
voltage can be measured on regulators U118 and U119
and test points TP1000 and TP1003. The digital board
also produces +60VDC used to power the ßuorescent
display. If this voltage is not present, the digital board
is faulty. The lithium battery should measure 3-
3.25VDC between the case (+) terminal and chassis
ground.
CAUTION
Do not operate the Model 7001 with
the digital board shield removed for
an extended period of time, because
the shield acts as a heat sink for one
of the +5V regulators.
Most connections between the digital board and other
boards are made through mass termination connectors,
so there is a minimal chance of problems due to broken
wires.
Symptom Diagnostics do not run:
•
Suspect a faulty digital board, display board, or
power supply.
Symptom A "No Comm Link" error indicates that
the digital and display boards are not communicating.
If this error occurs, check:
•
Defective battery.
•
Bad cable between digital board and display
board.
•
Defective digital board.
•
Defective display board.
7.8.2 Display board
The display test veriÞes individual characters and an-
nunciators on the display board. If the instrument
powers up and executes this test, the display board and
digital board logic are most likely operating properly.
Problems with individual characters or annunciators
Artisan Scientific - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisan-scientific.com
should be easily identiÞed. If the display is dead, check
the condition of the ribbon cable connecting the digital
and display boards. Serial communication and power
for the display board (including 60VDC), are transmit-
ted over this cable.
Symptom No display:
•
Defective power supply board. Check voltages.
•
Blown fuse (power supply board). Check fuse.
•
Loose power cable from power supply to digital
board.
•
Loose cable from AC receptacle to BNC board.
•
Loose power feed from BNC board to power sup-
ply board.
•
Loose ribbon cable from digital board to display
board.
•
Defective power switch (BNC board).
•
Defective display board.
•
Defective 60V supply (located on digital board).
Symptom Front panel buttons not working as ex-
pected:
•
Check the display board (run BIT)
•
Check for broken or damaged contacts on key-
board button membranes.
Symptom Display tests run but show incorrect char-
acters:
•
Change display board.
7.8.3 Power supply
The Model 7001 power supply will resist problems af-
fecting conventional power supplies. The power sup-
ply automatically adjusts to a broad range of mains
voltage (90-260VAC) and frequencies (47-440Hz), so
the fuse should not fail because of incorrect mains volt-
age setting.
If the power supply fails, the instrument will be inop-
erative. Power supply input and output voltages may
Maintenance
7-15
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