HP-IL device Seal s5801c

[John Keith]

The X and Y capacitors (plastic boxes), toroids and transformer are standard for both US and European mains-powered equipment. One way to determine the line voltage would be to trace the connections to the primary side of the transformer(the left side in the 2nd. pic in post #1). If there are 4 active pins on that side, it is a dual-primary transformer that can be hooked up to run on either 120 or 240V.

In any case I think that it would be safe to connect the transformer briefly to 120VAC and see if the logic circuitry is getting 5V.