Step 1: Gut the Cabinet.
Some of the pieces you remove may be useful. Keep what you think you will need for this project, or another future project.
I saved the wooden piece that separates the TV from the Speaker enclosure. You'll see what I used it for later.
Step 2: Build the Inside Cabinetry.
This project took almost an entire sheet of plywood.
1) From the images in step 1 you can tell that the cabinet does not have a back. I measured the inside opening and cut a piece to fit (I will leave all the mwasurements off this instructable since all TV cabinets have different dimensions).
2) I nailed the new back piece to the two rear verticals.
3) The removal of the front speaker area revealed that I would need to raise the new cabinet "floor" a bit. I used some scrap lumber and made two pieces after I measured the depth and length between the front and rear verticals.
Step 3: Build the Cabinet Floor.
1) I cut this square shape out and notched the two front corners so I could snugly fit it beteen the verticals.
2) Nail the floor sides and front straight down into the base of cabinet. The rear will have to me nailed from the back.
Step 4: Make the Sides
1) Cut the 2 sides, mark the face that will not be visible so you know which is the better side.
2) I used a shelf system that would allow me to move the shelves to wherever I need them. Cut grooves for this system using a Router or a table saw with Dado blades. If you will not be moving the shelves once installed, than just use two pieces of wood strips as shoulders and nail them to the cabinet sides.
3) I opted to paint the cabinet interior with a satin black. I suggest painting the cabinet sides before installing the shelf system. I also painted the already installed the cabinet back and floor at this time.
Step 5: Install Cabinet Sides
I slipped the cabinet sides into their respective sides. I dry fitted them earlier and marked each side with the corresponding L and R, as well as T and B (top and bottom). I then nailed the sides to all four uprights. I positioned the nails diagonally and recessed them.
At this point you can touch up any scrapes and scratches to the paint.
Step 6: Make the Shelves
Step 7: That's It! We're Done.
I had some serious ideas for this cabinet. I wanted to turn it into a laptop desk/cell phone charging station/ filing cabinet/etc., etc. But since this was something I made for my mother for Mothers Day I turned it into something she wanted/needed - a simple paperwork hidey-hole to keep all her documents.
For a little but of unintended irony, Mom sits her 32" TV on the top of the cabinet. Maybe I'll put a lazy suzan on the top of this thing so she can position her TV with ease.