Tektronix 213 DMM Instruction Manual page 44

Maintenance-213 Service
NOTE
New crt's are supplied with the trace rotation
coil already installed. If the trace rotation
coil is faulty, contact the nearest Tektronix
Field Office or representative for assistance.
Reassembly. To reassemble the crt assembly, proceed as
follows:
1. Insert the crt into the shield with the trace rotation coil
leads on the opposite side from the shield seam. Insert the
crt support ring from the crt socket end of the shield, and
carefully push it down inside the shield with a small blunt
instrument until it is about 1 /8 inch beyond the soldered
lead on the shield.
2. Reinsert the shield lead terminal connector into the
plastic holder.
CRT REPLACEMENT. Replace the crt assembly in the
reverse order of Removal. Insure that the seam on the crt
shield is facing toward the top of the instrument.
POWER SUPPLY BOARD REMOVAL. To remove the
Power Supply Board, perform the Removal steps of all pre-
ceding components, except the crt, then proceed as follows:
1. Disconnect the terminal connector holders that are
connected to the Power Supply circuit board from the Secon-
dary Power Supply and the PWR (BTRY) LED.
NOTE
Take care in removing this board, as there is
another terminal connector holder on the
instrument side of the bottom of the board
which is disconnected after the board is
removed.
2. Gently I ift the board up and just free of the Amp I ifier
Board, then tilt the top away from the instrument and dis-
connect the terminal connector holder that is on the cable
from the crt base socket.
Disassembly. Further disassembly involves removing the
shields for troubleshooting, repair, or replacement of parts.
Proceed as follows (see Figure 4-5):
4-6
WARNING
I
If this board is to be reinstalled in the instrument
for troubleshooting, removal of the shields ex-
poses a shock hazard on the board. Also, if the
terminal connector holder from the Secondary
Power Supply Board (P420) is not connected to
the Power Board and the instrument power
plug is connected to and then disconnected from
the power line, the two large capacitors (C417
and C418) under the shield on the parts side of
the board do not discharge which could create
a possible shock hazard.
1. Being careful not to lose the small spacers under the
laminate shield (on soldered side of board), remove the
three screws from the laminate shield and remove the shields
on both sides of the board.
2. The metal I ic shield can be further disassembled by re-
moving the three screws holding the two plastic posts and
one metal post (note that the metal post is installed on the
board adjacent to the thick film resistor). The mylar in-
sulator attached to the metal shield is held in place with a
piece of double-stick tape.
Reassembly. Reassemble the shields in the reverse order of
Disassembly. If difficulty is encountered in keeping the
ring spacers in place under the laminate shield during re-
assembly, two suggested methods for reassembly are as
follows:
1. For the first method, set the metal shield with the mylar
insulator in place on the board and place these on a flat
surface with the board on top. Place a ring spacer on the
board hole nearest the power line cord, insert a screw through
the corresponding hole in the laminate shield, set the shield
in place, and just tighten the screw until the threads catch
hold. Gently lift the laminate shield and place a ring spacer
over the board hole near the ASTI G adjustment hole. Then
insert a screw and again just tighten it until the threads
catch hold. Slide the last ring spacer in place over the hole
near the battery terminal pins, insert a screw, and then
tighten al I the screws.
2. For the second method, install the screws in the laminate
shield and set it on a flat surface with the writing side of the
shield down. Install the ring spacers and set the board in
place on top of the spacers. Remove the posts from the
metal shield and install them on the laminate shield screws.
Then install the metal shield with its mylar insulator, and
install and tighten its attaching screws.
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