German tanks had a rotating electrical connector beneath the center of their turret. One or more cables ran from there up to a junction box or boxes in the turret, and various power leads and communication wires emerged from the boxes.
In the Pz.3, the junction box was on the turret's rear wall, above the left-hand pistol port.
The Pz.4 had a turret floor with three support legs at the front, under the gun. Its junction box was placed on the front of these legs, out of the way. It is indicated in this photo, almost hidden between the turret front and the hull structure.
This box was a standard component called the Kasten Panzer 5c. It was also used in the Tiger E, the Panther and the Tiger B. It would almost certainly have been used in the production VK3601.
The Pz.4 had another electrical box, lower down, which is also visible in the photo. This one was for its electrical motor. Revosys have put a similar motor in this kit (parts H23,H24) and so we could expect to find this box in their imagined tank. Moreover, since they have modelled their VK3601 turret after the Pz.4 turret, with three support legs at the front, we could expect to find these two boxes in the same places.
But Revosys' kit does not contain either of the boxes from the Pz.4. It has the pre-war box from the Pz.3 (parts V15,V16) and the kit instructions tell us to put the box on the rear turret wall, same as the Pz.3