Doctor Octoroc
Offline
Philadelphia

I built a custom Gameboy DMG awhile back with an IPS screen and it works well for the most part but has problems from time to time - usually double-booting or blank screen. I'm not using a flash cart or any additional mods (just pro sound but that doesn't mess with voltage as far as I know), just running the MGB cart for music. I'm 99% sure it's related to power issues but in trying to find the best solution, I can't seem to find any solid answers on what is the best fix or how to implement. As far as I know, I have two options but figured I'd tap the pros here for advice. I've searched this forum, YouTube and Google without any luck thus far.


The first option, as far as I know, is adding a buck/boost.

I have this Pololu 5V Step-Up/Step-Down Voltage Regulator on hand, along with the two leads pictured:

However, I can't seem to find any documentation on installing it into a DMG specifically. I know from this video that it needs to be wired to the unregulated pin(s) on the power regulator board but I'm not sure where it needs to be wired to the IPS screen's PCB. This guide says to wire the Pololu VIN to the positive unregulated pin on the DMG's power regulator and wire the Pololu GND to the negative/GND lead on the power regulator board. I can do that much.

But I don't know where on my IPS mod to wire the other two it mentions. The first says "Output voltage: Wire to the positive end of your mod" and the second says "Ground: Wire the ground (-, black wire) from the mod to ground on the voltage regulator". So obviously, this guide is referring to a traditional backlight mod with clearly colored wires but since the IPS is a drop-in mod and I'm not good at reading circuits, I would need some direction (preferably a visual guide) as to where the other two connections would need to be. This is the IPS mod I have although I believe I have the V2 since I installed it well over a year ago.


The second option, I believe, would be the Retro Six Clean Power board.

This, I can do without further need of instructions as it's just a swap but I don't have this on hand so I'd need to acquire it.

So I guess my first question is which one is preferable? Would it make any sense to do both or is one or the other sufficient on its own.

And my second question is, if I go with the Pololu, are there any guides out there for installing this in conjunction with an IPS mod? Alternatively, is anyone able to help me figure out where on my IPS mod the other two connections need to be? I can post images of the PCB of my specific IPS mod if it will help but as far as I can tell, aside from mine being a green PCB and the V3 being black, the layout is exactly the same.

Last edited by Doctor Octoroc (Jun 6, 2021 2:59 pm)

Split
Offline

You may have already found the solution at this point but I'll give you my experience with this set up so far.

It looks like the Pololu you have on hand is the S10V4F5? The one I have been using with a FunnyPlaying Retro Pixel IPS kit is the S7V7F5 and the specifications appear to be pretty close to the one you have on hand. Of course the S10V4F5 has the SHDN input as well. I don't think the SHDN would be used in the case of a DMG if I remember correctly from other posts I have seen, I would love for someone else to chime in on this to confirm though. At least according to Pololu's product page it would need to be "driven low or left floating." My only experience so far has been with the S7V7F5 model so I'm afraid I can't speak confidently beyond it but I have been happy with the Pololu branded components as a whole.

For the wiring I used my Pololu entirely in place of the original regulator, not in conjunction like a traditional backlighting method. The connection is like so:

Pololu        DMG CPU Board

VIN - - - - - VCC (green top)
GND - - - - - GND (green middle, marked with G)
              ( - ) (green bottom)
VOUT  - - - - ( + ) (red)

The connection on the CPU board that I am using for the regulator is right above where the audio board connects (the audio connection being the four through holes with the little triangle pointing to one of them) and the diagram above assumes the original green and red wires are still in place. If they're not, that's fine too. You can just use a 26 AWG wire to hook it up to the same area. The ( - ) connection (negative voltage rail) on the CPU board is not used at all in my case. After asking around I've found the FunnyPlaying IPS kit does not use the negative rail whatsoever. The CPU board schematics show the negative line going directly to the 3rd pin from the left on the ribbon cable connection if you are interested in tracing this connection on your kit to see if it's used.

I have a little 3M Command velcro-like pad trimmed down attaching the regulator to the wall of the battery compartment where the old regulator sat, makes it easy to remove the guts if needed but keeps the regulator from rattling around. I imagine some kapton tape could work too.

All in all I've been very pleased with this set up and have not had any apparent issues using the IPS along with an EverDrive X3 powered from a Pololu. Granted, the battery life has been shorter, but that's to be expected I think.

I documented some of these IPS related findings in a thread I made a few months ago (that you were kind enough to contribute to!) so if you're interested check back in on it here. Hope this helps you along your way!

Last edited by Split (Jul 18, 2021 12:33 am)

Doctor Octoroc
Offline
Philadelphia
Split wrote:

You may have already found the solution at this point but I'll give you my experience with this set up so far.

It looks like the Pololu you have on hand is the S10V4F5? The one I have been using with a FunnyPlaying Retro Pixel IPS kit is the S7V7F5 and the specifications appear to be pretty close to the one you have on hand. Of course the S10V4F5 has the SHDN input as well. I don't think the SHDN would be used in the case of a DMG if I remember correctly from other posts I have seen, I would love for someone else to chime in on this to confirm though. At least according to Pololu's product page it would need to be "driven low or left floating." My only experience so far has been with the S7V7F5 model so I'm afraid I can't speak confidently beyond it but I have been happy with the Pololu branded components as a whole.

For the wiring I used my Pololu entirely in place of the original regulator, not in conjunction like a traditional backlighting method. The connection is like so:

Pololu        DMG CPU Board

VIN - - - - - VCC (green top)
GND - - - - - GND (green middle, marked with G)
              ( - ) (green bottom)
VOUT  - - - - ( + ) (red)

The connection on the CPU board that I am using for the regulator is right above where the audio board connects (the audio connection being the four through holes with the little triangle pointing to one of them) and the diagram above assumes the original green and red wires are still in place. If they're not, that's fine too. You can just use a 26 AWG wire to hook it up to the same area. The ( - ) connection (negative voltage rail) on the CPU board is not used at all in my case. After asking around I've found the FunnyPlaying IPS kit does not use the negative rail whatsoever. The CPU board schematics show the negative line going directly to the 3rd pin from the left on the ribbon cable connection if you are interested in tracing this connection on your kit to see if it's used.

I have a little 3M Command velcro-like pad trimmed down attaching the regulator to the wall of the battery compartment where the old regulator sat, makes it easy to remove the guts if needed but keeps the regulator from rattling around. I imagine some kapton tape could work too.

All in all I've been very pleased with this set up and have not had any apparent issues using the IPS along with an EverDrive X3 powered from a Pololu. Granted, the battery life has been shorter, but that's to be expected I think.

I documented some of these IPS related findings in a thread I made a few months ago (that you were kind enough to contribute to!) so if you're interested check back in on it here. Hope this helps you along your way!

Thanks for the response! I ended up trying out the clean power board from Retro Six - some swear by it, others say it doesn't work well but it seemed like the most straight-forward fix. So far so good, except I botched the pro-sound mod so I only get sound from one channel haha. I'll have to fix that at some point but otherwise, it worked like a charm, and the documentation for installing it is available and easy to follow.