Not to jump into the middle of something here lol, but can't you add a decoupling capacitor to where the backlight connects to the regulator to reduce the buzz created by the backlight? Also, I toyed with the idea of connecting the backlight to the batteries but wouldn't the backlight be on all the time unless you install a switch? Forgive me if that's a stupid question, I'm not super knowledgeable when it comes to the gameboy's inner workings.
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The switch switches battery supply to the regulator board, so you'd connect it there, or input of the board.
Yes, you can add more decoupling caps to the board but the inductor has a particular inductance, the rectifier diode has a limited forward current, there are a copule of things that go into the design of a flyback converter, flybacks aren't known for their low output ripple. The nintendo supply is primitive.
Adding decoupling caps will generally reduce ripple but also increase current demands on the inductor and associated components. If the inductor can't supply the current, output voltage drops, inductors saturate, components get hot, things break.
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Could be a tight fit with a switching reg, better would be a drop in high current replacement for the standard power supply. Better overall supply ripple, not just for backlighting. Maybe something for the pocket to, I've heard it struggles with EMS carts
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Is there any chance of damaging the backlight if I connect it to the regulator input? If not I'd be interested in at least giving it try. Also do you know which solder point is the input? If I'm going to test it out I'd rather connect it there instead of the switch. I'd imagine it's one of the 4 wires running to the regulator and since I already have it connected to regulated output then I wouldn't have to reroute the wires to test it out.
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It would be best to adjust the resistor value for a full set of batteries rather than 5v regulated, but as Apeshit says you'd get brightness variations throughout battery life, and even pulsing as the batteries run really low. The option is yours, and I can get a pic when I get home.
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You'd need to tap onto the current limiting resistor for the power LED, not the LED itself
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I already had it wired board to board. I had it soldered directly to the output of the regulator board. I moved it up to the regulator input and it's actually greatly improved the contrast problem. Certain CPU intensive sections of games that would cause the contrast to flicker horribly are barely noticeable now. The regulator board isn't getting hot anymore either. I may still look into the variasuit mod from Nonfinite because I'd still like to be able to adjust the brightness but this seems to have helped quite a bit. As for batteries, I generally use a DC power supply. I don't run my gameboy off batteries very often.
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I already had it wired board to board. I had it soldered directly to the output of the regulator board. I moved it up to the regulator input and it's actually greatly improved the contrast problem. Certain CPU intensive sections of games that would cause the contrast to flicker horribly are barely noticeable now. The regulator board isn't getting hot anymore either. I may still look into the variasuit mod from Nonfinite because I'd still like to be able to adjust the brightness but this seems to have helped quite a bit. As for batteries, I generally use a DC power supply. I don't run my gameboy off batteries very often.
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Good to hear it sorted out a few issues. Keep us posted on the pro's and con's of your mod.
If contrast is flickering, may be a good time to swap out the caps on the reg board.
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I already swapped all the caps in the entire gameboy. It was one of the first things I did when I started having this issue. The contrast problems only happen when I'm using the EMS cartridge. It seems to draw more power than the official game cartridges. I've heard of people with backlights having contrast problems with the EMS and the Ever drive cartridges because they use more power. At least that seems to be the consensus.
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Yeah, they're all pretty power hungry. Never had that probelm with my carts though. Older CPLD's/FPGA's use a fair bit of current. Newer ones can shut down logic blocks that aren't being used.
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Well I've got backlit start and select buttons also which probably just makes the whole issue worse. My gameboy also has the older style regulator that only has a single cap instead of three. That may be part of the issue as well.
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Whaaaaaaaaaaaaaaaaaaaaat! backlit buttons!?!? Link me?