Troubleshooting 71
A1KPD Keypad
1. Remove the A1 Front Panel Board as described in that procedure.
2. With board removed. keypad can easily be lifted out of the Front Panel Assembly.
Rear Panel and/or A2 GPIB or Isolator Board
To remove these two assemblies together, proceed as follows:
1. Disconnect the cables from the following connectors on the A2 board:
a. Ac bias cable W6 from P101 (or J803 on 657xA).
b. Phone cable W4 from J107 (or J800 on 657xA).
c. Phone cable W5 from J108 (or J801 on 657xA).
2. Remove the AC input safety cover (2 screws) and line cord connections on rear panel.
3. Remove the DC output safety cover (4 screws) and the ±Output and ±LS sense connections on the rear panel.
4. Remove the "quick disconnect" plug (if present) from the analog connector (near OUT terminal) on rear panel.
5. Remove two screws securing the plastic output name plate to the ±bus bars.
6. Remove two screws securing the heatsink assembly brackets to rear panel.
7. Remove the nut securing the ground wire to the Output Signal ground terminal on the rear panel.
8. Remove two screws (one on each side) securing the rear panel to the chassis and remove the Rear Panel/A2 board.
To remove only the A2 board, proceed as follows:
1. Disconnect cables from the A2 board as described in Step 1.
2. Remove two screws securing A2 board to rear panel.
3. (667xA Only) Remove the two hex standoffs and washers securing the GPIB connector to the rear panel.
4. (667xA Only) Release GPIB board from holding bracket and remove board from the chassis.
Output Subchassis
The Output Subchassis houses the A5 Control Board, A6 Output Board, A7 Snubber Board, power output transformer,
choke and output heatsink assembly. The output power rectifier (D900) and the downprogrammer FETS (A6Q901/902) are
mounted on the output heatsink assembly. To remove the Output Subchassis, proceed as follows:
1. Remove Top Cover and RFI Shield as described under their respective procedures.
2. Remove the Rear Panel and A2 Board as described in the combined procedure.
3. Disconnect the two transformer T900 primary leads from the TB201 terminals (fuse clip type) on the A3 FET Board.
4. Disconnect cables from the following connectors on the A5 Control Board:
a. Phone cable W4 from A5J502
b. Ribbon cable W3 from A5J509
c. 2-wire cable W7 from A5J503 (position the cable away from and clear of output heatsink assembly)
5. Remove screw securing output heatsink bracket to the fan assembly.
6. Remove the screw (located between T900 and L200) securing the bottom of the Output Subchassis to the main chassis.
7. Remove three screws securing the side of the Output Subchassis to the side of the main chassis.
8. Slide Output Subchassis to rear, lift it up, and remove it from the main chassis.
A5 Control Board
Note The A5 Control Board can be removed from the power supply without first removing the Output
Subchassis as previously described.
If the output subchassis has not been removed, disconnect cables from the A5 board as described in Step 4 of the "Output
Subchassis" and then remove the A5 board as follows:
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