Monday, August 23, 2021

Custom Game Boy Design - Revitalizing Broken or Hard to See Portable Systems

It is a fact that the original Game Boy, its four widely available successors and its contemporary competitors had many excellent games but some truly awful screens by modern standards.  Handheld screen technology has advanced extraordinarily far since the rose-tinted glass days of 1989.  Today modding kits are available to fix or "upgrade" these machines with replacement screens, so let me discuss my own experiences with one.  

The WIP Version
Let's start with a problem that is not terribly uncommon.  You see a cheap handheld system for sale, you buy it just to discover that the screen is broken.  It can be cracked, it can have dead lines, or the polarizing layer may be burnt.  Alternatively you like Nintendo's handhelds but want to spare your eyes the ordeal of having to look at the hard-to-see screens.  You need a replacement screen, but as they don't make Super Twisted Nematic (STN) displays in the right size and with the connections required to interface with the system, you have to look for a more modern display.

I had a situation not unlike this.  My efforts to backlight a DMG Game Boy by removing the rear polarizing layer and installing a backlight have ended in failure twice, and similarly once I damaged a Game Boy Pocket screen trying to install the backlight.  I determined that whatever I was doing wrong, I was unlikely to get right the next time.  I still had the electrical components of one DMG that were perfectly functional, so I decided recently to restore it and make it work again and better than it ever did before.  

I saw that people really liked to customize their Game Boys, and the shell of the one I had was a bit yellowed.  Rather than throwing it into a UV-lighted hydrogen peroxide tub, I have read that replacement Game Boy shells were of good quality these days.  So I ordered an "IPS Ready" replacement shell made by Retro-Six, with buttons and a glass screen with custom colors, and a Retro-Six CleanJuice XL Rechargeable Battery Mod.  I am fond of clear cases and chose a blue-bordered glass screen and clear blue buttons.  I also got a Retro-Six CleanPower DMG DC-Regulator board to replace the old inefficient power regulator.  I ordered from both Handheld Legend and Retro Game Repair Shop because each could not provide all the parts I wanted in stock.  As I am located in the USA, it did not make sense, cost-wise, to order directly from Retro-Six, which is based in the UK.

One thing you may want to do during restoration is to replace the capacitors.  In one of my Game Boys the audio from one channel sounded substantially quieter than the audio from the other channel.  In both cases, replacing capacitors C3 and C4 on the DMG-CPU board (1uF/50V) gave the audio channels a much more equal balance.  In order to test the relative volume levels, use the game Space Invaders, it has support for positional audio for your shots.  If you shoot toward the left side of the screen, you should hear the shot on the left, if you shoot in the center, you hear from both and if you shoot to the right, you hear it on the right.  Use the headphone jack to judge the left channel and the right channel.

Even though the glass lens and the shell are "IPS-ready", you may want to file down a millimeter on the sides to prevent any blockage from the shell of the screen.  If you have them, use the screws from your old Game Boy unit.  They are much better than what are provided with the shells.  Even tri-wings are better than broken screw heads and screws which will not make good threads.  These IPS-ready shells have a flat cavity without ridges for the CleanJuice XL battery pack.

Installing the regular board requires removing the old board first from the four wires.  I just applied some fresh solder to the old joints and used the flat of my iron to heat up the whole joint area while applying gentle pulling force.  The ends of the wires should come away without difficulty.  Do not break the plastic keeping the wires in order.  The current board has the red wire identified and through holes instead of pads for the wires to solder.  The board also has a notch cut into one side, this notch should be facing toward the CPU PCB and lets the regular board fit snugly into the grooves provided to keep it in place.  If you solder the board in backwards, as I did, you can still fit the board into that area, it will just have to sit to the left on the other side of the grooves.  

The retaining bracket which comes with this screen kit has some play in it, so if you are not careful you may install the screen crooked.  Use double-sided tape to adhere the screen to the bracket and aim to have the screen flush with the lower right corner.  This bracket has cutouts for the posts which are normally snipped off during a DMG IPS screen install, which may help hold the screen in place.  The Retro-Six "IPS-Ready" shells do not have those posts on them, so you will need the tape to help keep the screen in place.  

The Final Version
Use plastic gloves when handling the glass screen or the IPS panel.  You do not want to leave fingerprints on the panel or the inside of the glass by mistake.  They are impossible to remove once you've screwed the LCD PCB to the front shell.  Keep a microfiber cloth handy to wipe away any dust that gets on the screen.  Dust can settle in between the glass of the shell and the screen.  A blast of compressed air may be helpful here too.

When connecting the circuit board to the screen use some kapton or electrical tape to hold the circuit board to the rear bracket.  The connector from the board uses connectors with a hinged door fastener which need to be pulled up and pushed down once the flat flex cable is in place.  The flat flex cable which connects the LCD PCB to the CPU PCB must be pushed in with some force, if you crease it that is OK.  Make sure the flat flex cable is not crooked once inserted.  

These replacement DMG screen kits do not solder the speaker, probably because the kit providers are too lazy to solder them in.  Two joints and you're done.  Make sure the shorter wire goes to the inner via and the longer wire to the outer via.  I reused my old speaker because it was in good shape, but replacement speakers can be purchased for a few dollars.

Another issue you will have is that the screw holes on the new shells are not pre-drilled, so you will have to apply extra force to cut screw threads into the holes.  You should not screw in the shell as tight as you possibly can, screw it in enough so the screen's color dial still moves freely but no more.  

Watching videos of installers is very helpful, but because modding kits tend to advance very rapidly, a tutorial video is likely only going to get you so far.  Macho Nacho's channel is one of the leaders in demonstrating how to install these kits, I suggest watching a few videos to get a feel of how mods work and are installed if you are new to the practice.  The IPS screen kit I purchased is called the DMG RIPS v4, which uses the Blackberry Q5 IPS display panel.  This panel is somewhat larger than a DMGs original screen, but they have their own glass lenses for them.  Another vendor called Funnyplaying also makes a quality kit.  I chose the RIPS kit because it allows you to use the menu to adjust the screen centering, which is very important in these machines.  

The IPS kit has eight built-in menu colors, green, yellow, black & white, red, light blue, dark blue, purple and yellow & pink.  You can cycle through the palette choices by pushing in the wheel that takes the place of the old contrast dial.  Turning the wheel up and down will increase and decrease the brightness of the screen.  Holding the button in brings you into the menu.  You can set a custom scheme with 64 choices for red, green and blue for each of the four shades of color the DMG can display. Here you can also adjust the horizontal and vertical position of the screen (100 levels), dial in the brightness specifically (20 levels).  You can turn on the Pixel Effect, which has been perfected over older models of these kits and something I highly recommend to give the IPS screen a texture not unlike the old DMG screen.  You can also toggle a battery icon being displayed over the image if you wish.  The menu also allows you to reset the menu to the factory default settings.

The CleanJuice XL battery is a really beefy rechargeable battery and with the Regulator board your DMG should last probably around 10 solid hours on a single charge, maybe longer.  The battery recharging board uses a USB-C connector and the Retro-Six shell I bought came with a battery cover with a hole cut out for the connector.  The recharging board has LEDs to show you the status of the charging.  I found that between the battery and the regulator board, the high pitched whine in the audio I got, mostly from the headphones, was eliminated.  There was still some hiss, but that is the nature of the DMG's amp.  

I am wary about the quality of replacement membranes and did not replace mine.  Perhaps I should have because the Right directional on the membrane I used was not quite as responsive as the other directionals and buttons. The Right directional often has the most wear of any of the directions, this is something I have seen in my Game Boy Pocket and Game Boy Color.  

These modern panels behave closer to the panel of a GBA SP, which uses a backlit active-matrix TN TFT panel.  The refresh is much faster than the old passive matrix displays.  There is no real motion blur or panel streakiness, but games occasionally took advantage of the slower pixel response times.  Those effects will look like flicker on these panels.  Serpent uses the effect on its attract mode demo to vary the brightness of the shades beyond the basic four shades.  Super Mario Land has glitches in the status bar that cannot be seen on a passive matrix screen but are quite noticeable on an active matrix screen.  Bubble Bobble 2 has screen tearing when scrolling which is hidden by the old STN panel, but the new panels, not so much.  So while you gain an awful lot by upgrading your display, you do lose a bit as well.  

I cannot close without discussing the price of the mod I did, it was not cheap.  The screen kit was the most expensive part of the mod, coming in at $52.99.  The CleanJuice Battery XL mod was also not in expensive at $34.99, but there is a cheaper non-XL version available.  The CleanJuice regulator board was $17.00.  The shell, buttons and screen lens were not too bad, but between all of these plus tax and shipping I spent $134.78.  That of course does not include the cost of the "donor" DMG and the amount I spent in the past on the backlight and bivert kit that ended up useless when the screen was destroyed.  All of a sudden that $200 Analogue Pocket might not seem so expensive, when it is in stock that is!

The Remains of an Old Game Boy

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