EMO box push button switches

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The EMO box (Emergency OFF) used on many PHI systems has switches that can become noisy, stick or fail to operate at all. These switches are used to turn on and off the card rack power, main electronics console power, vacuum console power, bakeout power and to turn off and reset all power.

Another very common issue is that the light bulbs in the switches tend to burn out on a yearly basis.  This blog post will describe where to get replacement parts for the EMO boxes.

The round red EMO button switch is still available but the original square push button switches that were produced by Cutler-Hammer (now Eaton) are very difficult to find. Honeywell equivalents are listed below.

There are two styles of EMO boxes.  The 32-005 style has a Bakeout switch and the other style has a Vacuum Console power switch.

EMO box
EMO box
32-005 EMO box
32-005 EMO box

Equivalent replacement switches produced by Honeywell are listed below.

EMO box switch
EMO box switch
EMO button McMaster-Carr PN 7403K42  
Main Power ON/Reset   Honeywell PN #: AML21CBA3AC
Allied Electronics Stock #: 70119090
Main Power / OFF Honeywell PN #: AML21CBA3AC
Allied Electronics Stock #: 70119090
Electronics  Console Power Honeywell PN #: AML21CBE2AD
Allied Electronics Stock #: 70119866
Vacuum Console Power Honeywell PN #: AML21CBE2AD
Allied Electronics Stock #: 70119866
Card rack power Honeywell PN #: AML21CBE2AD
Allied Electronics Stock #: 70119866
Bake Out Power Honeywell PN #: AML21CBE2AD
Allied Electronics Stock #: 70119866

Original lamp –

T1 3/4 Wedge lamp
T1 3/4 Wedge lamp

Lamp; Incandescent; T-1 3/4; Sub-Mini Wedge; 28V; 40mA; 0.3MSCP; 7000 Hrs

Manufacturer #: 85

Allied Stock #: 70013004

Recommended LED replacement lamp –

T1 3/4 LED wedge lamp
T1 3/4 LED wedge lamp

Lamp; LED; T-1 3/4; Sub-Mini Wedge; White; 28V; 40mA; 0.3MSCP; Lamp life 30,000 hours.

Manufacturer #: LED-24-T1.75 WEDGE-W Allied Stock #: 70012994

These LED lamps are more expensive but will last for almost 4 years compared to about 1 year for the regular tungsten lamps.

Mouser PN 560-LE-0509-01W is a white LED that would work for all of the switches and it costs less. Made by JKL Components https://www.mouser.com/datasheet/2/208/LE-0509-01-21680.pdf

Bonus – EMO box schematics are shown below

32-005 EMO box
32-005 EMO box
EMO box
EMO box

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