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Corrective Maintenance
1780R-Series Service Manual
6–13
Use the following procedure to remove the LV Power Supply board.
1. Remove the MPU Annex (A10), Waveform HV Supply (A16), and the Fuse
(A17) boards using the procedures given previously.
2. Remove the screws and one nut that hold the large and small metal shields in
place. The nut is located on the small shield. These shields cover the LV
Power Supply board and are used to hold the boards listed in step 1.
3. Remove the two screws that hold the AC line filter to the rear panel. See
Figure 6–3. Leave the AC line filter green/yellow ground wire connected to
the chassis ground stud. Slide the AC line filter out toward the rear of the
instrument as far as it will go.
4. Disconnect the cable connector from J600 on the LV Power Supply board.
Leave J120 connected to its cable.
5. Remove the four screws that hold the LV Power Supply air tunnel shield to
the chassis. Two screws are accessible by the rear cutout corners of the
board; the remaining two screws are accessible through the large holes
provided in the front portion of the board.
6. Lift the air tunnel shield with the attached LV Power Supply board out of the
instrument.
7. Remove the 13 screws to release the LV Power Supply board from the air
tunnel shield.
8. Slide the LV Power Supply board out toward the rear end of the tunnel
shield.
9. To re-assemble, reverse the procedure.
Use the following procedure to remove the Vectorscope board.
1. Disconnect three small connectors from J389, J498, and J574 on the
Vectorscope board (A6). Note the orientation of these connectors so they can
be reconnected properly when the board is ready to be installed.
2. Unplug the ribbon cable connector from J885 on the board.
3. Unsolder the blue, brown, green, and red wires from the board. Also,
unsolder (from the board) the wire that goes to the front-panel CAL OUT
connector.
4. Remove two nuts from the XY INPUT connector.
5. Remove the eight screws from the board.
6. Remove the board by moving the front end of the board outward and
forward.
Removing the LV Power
Supply Board
Removing the
Vectorscope Board