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Corrective Maintenance
1780R-Series Service Manual
6–11
6. Clean the face of the CRT to remove fingerprints.
7. Reconnect the PROBE connector to J498 on the Vectorscope board (A6).
Install the parts removed in steps 1 through 4 of the CRT Removal proce-
dure. Reconnect the ribbon cable connector to J138 on the MPU Annex
board (A10).
Use the following procedure to remove the Input & BNC board.
1. Remove the two screws that hold the metal shield to the chassis (see
Figure 6–3).
2. Remove eight screws that hold the circuit board to the chassis. (Four of the
screws are ground screws located between the channel INPUT BNC
connectors.) See Figure 6–3.
3. Unplug four connectors from the Waveform Monitor board (A2). These
connectors are J1322, J1331, J1231, and J1133 on A2.
4. Lift the circuit board with attached cables out of the instrument.
5. When reinstalling the Input and BNC board, CH-A connects to J1322,
CH-B1 connects to J1331, CH-B2 connects to J1231, and CH-B3 connects
to J1133 on the Waveform Monitor board.
Use the following procedure to remove the Fuse board.
WARNING. Before attempting any disassembly/assembly of the instrument, be
sure to disconnect the power cord.
1. Remove the two screws that hold the clear plastic cover in place.
2. Remove two 1/4-inch hex-shaped posts.
3. Note the color (brown, blue, blk-gry to minus, gry to center, red-gry to plus)
and connection locations of the five wires soldered to the board. Unsolder
these wires.
4. Remove the two screws that hold the board in place.
5. Remove the board.
6. To re-assemble, reverse the procedure.
Removing the Input &
BNC Board
Removing the Fuse Board