Fluke 900 - Manual (Page 81)

FLUKE 900 SERVICE MANUAL Maintenance
U60 SYS-AF
U61 SYS-B
U76 SYS-C
U77 SYS-D
U74 Custom ]
U75 Standard
The EPROM positions are shown in the layout diagram of Section 6
(Schematics). Do not Mix the EPROM devices as the unit will not operate
properly.
Reassemble the unit by reversing the disassembly instructions. In particular, make
sure that the display controller, speaker wires and keyboard cables are connected.
It is recommended that you not screw the top and bottom parts together with the
final 4 screws, until you verify that the tester passes selftest.
5.2.4 Fuses and 110/220 V Conversion
The line fiise is located in a recessed compartment next to the power cord receptacle. To
replace it, remove the power cord and slide the clear plastic panel over, exposing the fuse
receptacle. Pull the black plastic lever to pop out the fuse. The proper rating for replacement
fuses is 3A, 250 V.
For conversion between 120 V and 240 V, the small circuit card under the fuse must be
removed, turned over and reinserted. The voltage setting is marked appropriately on each
side of the card. To slide the clear plastic cover over completely to allow removal of the small
card, it is necessary to flex the adjacent top cover of the tester.
5.3 Disassembly and Assembly Instructions
Before replacing any system modules, turn the unit off, remove the power cord and disconnect
the Interface Buffer.
5.3.1 Microprocessor Board
1. With the unit face-down, remove the four screws from the bottom of the unit which
hold the upper and lower halves together.
2. Turn the unit face-up and raise the right side of the top half up and to the left,
somewhat like opening a book. This will expose a connector (J3) which attaches the
two halves.
3. Press the ejectors at either end of the male connector and remove the mating female
connector. The two halves should now be completely separated.
4. Remove the connector (upper left area of top half, component side) attaching the
Micro Board to the Display Controller Board.
5-3