M-TI SCR Instruction Manual

Instructions of Installing Solid Trigger into Furnaces
1. How to replace solid trigger:
There is a solid 12-pin trigger with in the furnace, which is used to control SCR (see
Fig.1). Please open the back cover at the back of the furnace and loose the screws at
bottom of the trigger before taking it out.
Fig. 1 the top view of a solid 12-pin trigger
Fig.2 shows the view of control components in the furnace, such as connection panel,
relay, SCR, trigger, mutual inductance, 4A fuse, and 32A fuse.

Fig. 2 the view of control components in the furnace
Before disconnecting the old trigger please must remember the connection diagrams
(see Fig. 3 and Fig. 4) and follows the diagrams to install the new trigger.
On the SCR there are 4 connecting pins (A, B, C, and D). Please only connect pin A
and pin B (two pins in the middle) on SCR.
For other connections please see Fig. 4 to know in detail.
Fig. 3 the connection diagram between the trigger and SCR

Fig. 4 the connection diagram on the trigger
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MTI Corporation
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