Agilent Technologies 1200 Series Reference Manual page 129

Do not connect a power plug to the quaternary pump
after removing the top covers.
A safety light switch on the main board will prevent
operation when the covers are removed.
The next figure shows the position of the safety light
switch on the board.
1200 Series QP Reference Manual
7 Note the position of the safety light switch on the main
board.
Repairing the Pump
Top foam cover
Light light switch
Foam lever
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