SCR Assembly

TM 10-3930-609-35

partment (TM 10-3930-609-12).

(1) Remove cover from

control

panel

(2) Remove machine screws, lockwashers

compartment (TM 10-3930-609-12).

and flatwashers which secure forward and reverse relay

to mounting panel (fig. 2-14). Withdraw relay from

Note

mounting panel slightly for access to terminals.

When disconnecting leads from

(3) Disconnect two leads 18A from forward

terminals at which two or more leads

control coil (left hand coil).

terminate, replace the screw and the

leads not requiring disconnecting

(4) Disconnect two A2 leads from bus

immediately after removing the

connecting two lower contact supports.

required lead.

(5) Disconnect lead T2 from upper contact

support.

(2) Disconnect leads A2, T2-1, and NEG from

(6) Disconnect leads F2 and F8 from relay

terminals A2, T2 and NEG on SCR assembly

busses.

transformer (fig. 2-14).

(7) Disconnect two leads 77 and lead 74-from

(3) Disconnect lead A1 from shunt on SCR

left hand interlock switch; and, disconnect lead 72 from

assembly.

right hand interlock switch.

(4) Remove three capscrews, lockwashers

(8) Withdraw relay from control panel

and flat-washers which secure SCR assembly to

compartment.

mounting panel. Withdraw SCR assembly slightly for

b. Installation.

access to terminal board on left hand side.

(1) Connect lead 72 to terminal A on right

(5) Disconnect leads 49, 33, 45, 41 and 29A

hand interlock switch; connect lead 74 to terminal A on

from terminal board.

left hand interlock switch; and, connect two leads 77 to

(6) Withdraw SCR assembly from control

terminal B on left hand interlock switch.

panel compartment.

(2) Connect leads F2 and F8 to relay busses.

b. Installation.

(3) Connect lead T2 to left side of upper

(1) Connect control panel leads 29A, 41, 45,

contact support.

83 and 49 to SCR assembly terminal board terminals 2,

(4) Connect two leads A2 to bus. connecting

3, 4, 5, and 6 respectively.

two lower contact supports.

(2) Aline three slots in base of SCR assembly

(5) Connect two leads 13A to terminal on

with tapped holes in mounting panel and secure SCR

forward control coil (left hand coil).

assembly to panel with three capscrews, lockwashers

(6) Aline holes in relay base with tapped

and flatwashers.

holes in mounting panel and secure relay to panel with

(3) connect leads NEG, T2-1 and A2 to SCR

three machine screws, lockwashers and flat washers.

assembly transformer terminals NEG, T2 and A2

(7) Reinstall cover on control panel

respectively.

compartment (TM 10-3930-609-12).

(4) Connect lead Al to shunt on SCR

assembly.

2-30. SCR Assembly

(5) Reinstall cover on control panel

a. Removal.

compartment (TM 10-3930-609-12).

2-22