Wavetek 145 Instruction Manual page 38

6.4 DISASSEMBLY/REASSEMBLY INSTRUCTIONS
(For the Bench Instrument)
6.4.1 Disassembly
WARNING
With covers removed, several dangerous
voltage points may be exposed. Contact with
these points could cause serious injury or
death.
Review the following procedure and identify com-
ponents using chassis assembly drawing 01 02-00-0575
(refer to Section 7).
1. Disconnect the power plug from the line recep-
tacle.
2. Invert the instrument and remove four screws
fastening the bottom cover to the top cover.
3. Turn the instrument upright and remove the top
cover.
4. Remove the four screws fastening the lower
board to the bottom cover standoffs.
5. Remove the instrument from the bottom cover
and invert the instrument.
6. Unsolder the No. 18 black wire at the solder lug
of FUNCTION OUT BNC.
7. Disconnect the following wires from the
generator board locations:
E28 (coax) and E29 (shield) function output;
E26 (yellow) and E27 (white-black) Ext DC;
E6 (green) and E7 (white-black), GCV;
E1 (brown) and E2 (white-black), VCG;
E4 (red), E5 (brown) and E3 (orange) dial pot.
8. Remove all knobs except the dial knob.
9. Remove four screws fastening the generator
board (upper board in this inverted position) to
standoffs between the boards.
10. Tilt the front panel forward and slide it forward
enough to clear the detents of the generator
board and lift the generator board free. Slide the
front panel back over the detents of the remain-
ing board.
11. For troubleshooting, set the generator board
component side up on the working surface along-
side the rest of the instrument. Ensure that the
generator board is lying on a nonconductive sur-
face and it is not making physical contact with
the rest of the instrument. A jumper wire may be
attached between E3 and E4 of the generator
6-2
board to simulate a top-of-dial frequency
voltage. It may be necessary to replace some of
the knobs to set up various test conditions.
At this point, the entire instrument is accessible
for troubleshooting. To reassemble, perform
steps 6 through 16, paragraph 6.4.2.
12. To completely remove the generator board,
disconnect the following wires from the
generator board:
E21 pulse disable;
E23 pulse select;
E24 pulse coax;
E25 pulse coax shield.
Disconnect the Molex connector. To reassemble,
perform steps 1 through 16, paragraph 6.4.2.
13. To remove the trigger/pulse board, remove the
two screws connecting the power switch to the
trigger/pulse board.
14. Unsolder the following wires from the trig-
ger/pulse board:
E1 (blue);
E2 (white-blue);
E3 (blue);
E4 (red);
E5 (white-red);
E6 (red);
E7 (green);
E8 (green);
E9 (blue);
E10 (red);
E11 (violet);
E12 (white);
E13 (white);
E14 (white);
E15 (gray);
E16 (orange);
E17 (red);
E18 (white-black);
E 19 (yellow);
E22 (brown);
E48 (green);
E30 (coax, center conductor);
E31 (coax, shield);
J6 (TIL BNC), E40 and E41 ;
J5 (TIL BNC), E42 and E43;
J4 (ECL BNC), E44 and E47;
J3 (ECL BNC), E45 and E46.
15. Unsolder the green-yellow wire connecting the
front and rear panels.
16. Slide out the trigger/pulse board.