The Picade is a great little device that pretty much anyone can put together with nothing but a screwdriver.
It does, however, have a few shortcomings and room for improvements.
The most obvious shortcoming is the 8 inch screen shipped with the Picade. It's good, but it's only 8 inches. The cabinet is designed to take a 12.1 inch screen with a 4:3 aspect ratio but such screens are hard to come by these days.
The second shortcoming is the absence of a power supply. The reason might be that shipping the Picade with power wirings and/or a power supply would make it an electric device and create certain regulatory requirements.
And then, of course, you can always add bling in the form of illuminated buttons and a brand Joystick.
On Aliexpress I managed to find a an old style 12.1 inch 4:3 LCD screen with a driver board. The screen used in the Picade is typically a laptop LCD panel and panels can't interpret hdmi signals directly but need a separate driver board. The driver board contains the hdmi input, decodes the signal and feeds it pixel per pixel to the panel in the simplest possible way. The board also provides the panel with power for the backlight illumination.
Unfortunatelly, the screen I got had an old style CCFL (Cold Cathode Fluorescent Lamp) backlight and not modern LED illumination. The larger size was a nice upgrade compared to the stock display shipped with the Picade. But the colors looked a bit washed out, the image was dim, viewing angle VERY limited and the backlight was uneven. When viewing a black screen it only looked black in the middle and towards the edges it looked light grey because of bleeding from the backlight.
Eventually a came across LED illuminated screen of the same size (LTN121XL01-N03) but it had no driver board. Luckily a store on Ebay offered a driver board for this specific panel. It is still not as good as todays excellent IPS and OLED displays found in modern laptops and tablets, but it is good enough. Black screens are black from edge to edge and the viewing angle is great - if you can see the screen, you can se what's on it.
However, the larger screen brought along a new challenge. The original 8 inch screen was powered by a 5 volt USB signal but the 12 inch screen requires 12 volts.
My first solution was a single power brick with an old Molex connector, the kind that was used for old hard disk adapters. The Molex connector has 4 pins; two for 5V and two for 12V. I wired the 12V to the LCD panel and 5V to the Raspberry Pi 3. It worked, but the Raspberry kept showing the rainbow icon every now and then warning that it wasn't getting quite enough power.
My next solution was a good quality 12 volt and 3 amper power brick with a barrel connector (5.5x2.1mm) as well as a separate 12V to 5V step-down converters intended to be used in cars and motorcycles to turn 12V into a 5V USB port for charging. With a simple Y cable I connected the power supply to both the LCD panel and to the step-down converter which in turn powered the Raspberry.
This turned out to be a very good solution and I have not seen the rainbow icon since.
And when using a common barrel connector you can easily add a switch to the cable aswell, such as this which can be bought for a couple of dollars. I always use the shutdown option Retropie but afterwards I cut the power with this - that way I can start it again by flipping the switch back on.
But just working well isn't enough. A machine like this requires some bling and what better way to add bling than with LED lights.
There is nothing wrong with the original Picade joystick but a Sanwa ball top joystick is considered great and can be bought for about 20 Euros. The Sanwa JLF will fit directly with the screw holes lining up exactly as the original one but the JLW will not fit.
For the six action buttons next to the joystick I wanted illuminated buttons with chrome rings. I also wanted an even illumination and not too bright so I went with the Ultralux buttons with 5v LED lights. A benefit of the 5v LEDs is that it can be both powered and controlled with a board and single USB cable. I got the PacDrive LED driver board for this purpose, small enough to be attached to the bottom of the action plate next to the buttons.
The Ultralux buttons are very nice looking but they are also huge and will fit in the Picade with very little room to spare. However, they will not fit on the sides so for that I got Seimitsu PSL-30N-5W2 buttons. Compared to the original buttons, the Ultralux buttons with microswitches are a bit noisy and requires quite a lot of pressure. In games requiring frantic fireing troughout the game (such as R-Type) you might wish you had lighter buttons.