Understanding this circuit? battery charger

[fastline]

I quickly drew up this circuit area to try and understand it. This is part of a battery charger. 120VAC to 24VDC/20A. AC power is simply directly to a step down transformer, then through rectifier diodes and oil filled cap.

I am rather confident this alternistor is toast as the gate is shorted to T1. However, I am trying to source a replacement and trying to understand the circuit better to make sure I spec the triac correctly.

The triac is a Q4025P, an opto is a MOC3031

From the looks of the circuit, it looks like the gate gets AC power? How can that be right? It almost looks like the circuit is designed to take advantage of the Vdrop through the triac to operate the gate but....

 

[vincehhh]

The gate is on the outer pin.

looking from the top

--------------------
--------------------
| t1 t2 G |
|______________|

If you measure with meter on ohms
t1 to t2 should be open cct
t1 to G should like like a diode ( open cct one direction 500 or so ohm the other)
t2 to G should look like a diode

a short between any pin indicated a fault

 

[remon7]

It does not make any sense about SV (???) and what do you
mean about opto? Is it Opto electronics?