Maintenance-4 55/A2/B2
VOLTS/DIV Switch Assembly Removal
To remove switch assembly:
1. Remove VAR knob using hex wrench.
2. Pull off VOLTS/DIV knob.
3. Remove POSITION shaft-knob.
4. Unplug J4140 or J4240 from Vertical board.
5. Remove switch shield, held with 4 screws.
6. Remove long-narrow shield from back of Vertical board;
held with 3 screws.
7. Unsolder components from terminal projecting through
Vertical board.
8. Unsolder 43 £2 resistor and ground connection from
input connector.
9. Remove two remaining screws holding switch assembly.
10. Pull rear of switch assembly away from Vertical board
far enough to unplug pin connectors and release indexing
keys from module frame. Remove switch assembly.
To re-install switch assembly:
Reverse order of above procedure. Make sure that pins on
gain substrate align with sockets on Vertical board.
To replace VOLTS/DIV switch components:
Do not disassemble VOLTS/DIV switch unless absolutely
necessary to replace components.
If obtained apart from the associated equipment and from any vendor other than
aa4df or ralph.d.m iller, you have been sold stolen property. Please demand a
refund, and if applicable, file a com plaint with eBay.
If disassembly is necessary, read the following list of special
considerations before beginning disassembly (see Fig. 5-7).
Substrate or Contact Replacement Considerations
1. Front shield is soldered to front edge of contact strip
and must be removed before bottom frame can be removed.
2. Substrates and contacts can be removed without remov
ing actuator assembly.
3. Do not touch contact or substrate surfaces. Contamina
tion can occur, causing intermittent or noisy contacts.
4. When installing contact strips, observe guide pin alignment.
5. Ground clip is sandwiched between top gain-contact
strips and bottom frame. A relieved portion is provided in
bottom frame for accepting lip of ground clip.
Actuator Assembly Replacement Considerations
1. Actuator assembly is held by two keepers that are mold
ed into top frame. These keepers can be easily broken if
the following is not considered.
Insert a narrow-blade screwdriver between rear actuator
bearing and one keeper. Carefully rotate screwdriver to pry
keeper away from bearing lip and release one side of bearing.
Release other side of bearing in same manner.
j> CAUTION <j
Be extremely careful not to force keeper
beyond point where bearing is released. It
can easily be broken. If keeper breaks, top
frame must be replaced.
2. After actuator bearing is released, remove actuator
assembly by pushing bearing completely free of its mount
ing and pulling front of actuator off front bearing.
REV. A, OCT 1975
5-9
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