Ohhh, the VTAS. What a system.
The main unit sat under the RIO's seat, I think. In the A-4, obviously, only 1 seat, the pilot's.
Not very big, maybe 5 lbs. Almost invariably, the problems it had involved a burnt wire under the cards. The cards were surprizingly reliable. There were a few thousand wires, connecting everything to everything else on the bottom of the VTAS. Pull off the bottom plate, and there they all are. A couple dozen small, Phillip's head screws to pull the bottom plate. Small little things.
All of the wires were white. None of them marked in any way. Easy, huh? We would spend hours tracing the wires from point A to point B, making sure we had the right one. The white wire, naturally. A couple times the size of a hair. VERY easy to break. Very weak.
Pretty easy to see, usually, which wires burned through. No problem. It was the white wire

They even made them a wire-wrap setup, so they are pretty easy to replace. Little electric drill looking device, zip unwrap the old, zip, wrap on the new. Of course, you had to be careful. It seemed like the burnt wires were always on the bottom of the post, so you had to replace a couple wires along with the burnt wires. No unwrapping a wire and re-wrapping it. You take it off, you replace it. We had a few spools of the stuff laying around, and we would go through a 100' spool on a single unit. Make sure there is no tag end sticking out. It WILL contact another post, and FFFttt. Start over.
You know. The white wire

And make absolutely sure the additional wires you replace go to the right place! One mistake, fffft! More burnt wires. The whole thing starts over.
A really fun system to work on. Is the sarcasm coming through ok?
Have fun all! It IS a truly great airplane. Extremely well done, inside and out, paint and systems.
Pat☺