Hardware GBA Backlight! (AGB-001)

pcm720 · Aug 20, 2017

Zmajchek said:
Hi Pcm720,

I've been measuring the current draw on my modified GBA yesterday and it is around 95 mA when playing a regular cart (Castlevania: Aria of Sorrow). This measurement was taken by using the 200mA input on my multimeter.

Just a warning to anyone who wishes to to measure the current – the multimeter needs to be connected in series, not in parallel because you are going to short the battery if you connect it in parallel (and end up blowing up the 200mA fuse inside your multimeter).

Well, I guess that sort of confirms my measurements. Also, what are your GBA model and screen type?
My GBA motherboard is AGB-CPU-02.

By the way, the fuse was blown because of a whole different reason a long time ago (4 or 5 years ago, I think).
Since this multimeter measures voltage and resistance just fine, I never got around to replacing the fuse.

dumblonde · Aug 22, 2017

Le_Gogh said:
Have a watch of this video, it should explain it to you.

are there any differences between screen a and screen ab?
screen a has better picture quality than sreen ab, maybe?

slaphappygamer · Aug 23, 2017

dumblonde said:
are there any differences between screen a and screen ab?
screen a has better picture quality than sreen ab, maybe?

I have both a 32pin and 40pin Gba. They are both have soldered adapters with aftermarket screens. I can't tell a difference, at least with my naked eye. Maybe someone with glasses has a different answer.

MNiceGuy · Sep 13, 2017

I admittedly didn't thoroughly read through the entire thread so I apologize if this was already asked:

This thread is linked in a RetroRGB summary of the Gameboy line which mentions this particular mod. In that section, the author states, and I'm paraphrasing, that the image quality of a Nintendo screen is significantly better than that of the third party options commonly found nowadays.

While I find the 3rd party screens adequate for my purposes, I haven't had an AGS-101 in front of me for many moons. Is there validity to that statement? Does it stand to reason one may want to go the extra mile (and likely the extra dollar) to source the real thing?

--------------------- MERGED ---------------------------

I'm curious how others feel about whether or not one of these modded systems has original/OEM hardware (screen, shell, buttons, etc.) or aftermarket. I have yet to find a 'donor' GBA (AGB) which is in good enough condition to consider reusing those parts so I've been using all aftermarket parts.

If you own both, can you tell a difference?

If you're thinking about buying one, would you pay more for an OEM one?

MNiceGuy · Sep 14, 2017

davidmorom said:
Hi everyone. In first place I want to thank everyone who discovered the method for modding the AGB-001 screen, and the people who posted their results so other people can learn about their mistakes and their success.

I also want to share my experience with these mods, in case anyone is interested, or maybe it is helpfull for someone.

The first time I tried to do this mod, I had a 40 pin board. I ordered the screen and the adapter on Aliexpress. It was a white tabbed one. The result as everyone knows now, was washed out colors. I tried shorting every combination of signals I read on this thread (RECV, GND, COM, P2-VEE...), but the best thing I get was right colors but TERRIBLE ghosting (the image was retained for even minutes). After a lot of tries, trying to fix it, connecting and desconnecting the screen, soldering points, etc. I ended up breaking the ribbon cable of the screen .

Reading that people had significantly more success with 32 pin motherboards, I found one on a local pawn shop. I ordered a second screen (white tabbed again), a 32 pin adapter, connected everything, tunned the potentiometer a bit, and voila, crystal clear image quality.

A few weeks ago I saw this post https://gbatemp.net/threads/40-pin-gba-with-white-tab-lcd-perfect-solution.448597/ so I decided to order a third screen, and try again the 40 pin motherboard. I just have to say, to anyone having trouble with a 40 pin motherboard, that this method absolutely fixes all the problems (washed colors, ghosting...). The result is as good as the 32 pin motherboard. Just remove R16, R17 and C33 for isolating P2-VEE on the board, short REVC to P2-VEE to take the unmodified RECV signal to the LCD, and remove C54 and Q3 to take the potentiometer directly to the LCD. A bit of tunning on the pot, and the result is PERFECT.

First off, I just tried your method last night and it looks great. Thanks to you, malheur and gaggi!

I wondering if there is any consideration to the other components we isolate when we remove R16, R17, C33, C54, and Q3?

In the attached file, I've highlighted in yellow the components removed for this mod. I'm curious if there are any considerations for the sections circled in red or blue?

The 40-pin Type-A cable I'm using does indeed forward pins 31 and 33 on the GBA to the 101 LCD as such:

AGB 101
(31)P2-VSS------>(29)P2-VSS
(33)VDD--------->(28)P2-VDD

By completing this mod, pins 31 and 33 are no longer supplied. Without knowing the exact requirements of an AGS-101 LCD, I can only go off the fact the adapter cable designer did go to the trouble of forwarding those pins to the screen. What side-effects, if any, there are from not supplying the screen with these?

SSG Vegeta · Sep 15, 2017

Hanafuda said:
So, he took the screen from an AGS-101 backlit SP, and put it in an original GBA??? What a waste.

Not really for those of us who hate the Sp but want a backlight it's not a waste

--------------------- MERGED ---------------------------

DeMoN said:
Not a waste, I prefer the design and buttons of the original GBA to the SP.

My bro ^^

Hanafuda · Sep 16, 2017

SSG Vegeta said:
Not really for those of us who hate the Sp but want a backlight it's not a waste

--------------------- MERGED ---------------------------

My bro ^^

Yeah, it's even more of a waste now than it was then (5 years ago, when I made that post you just replied to for some reason). There are, or have been, other sources for screens since then, making the destruction of a perfectly good SP unnecessary to do this mod.

I do prefer the SP format, and its clicky buttons vs. the original GBA mush buttons. And it's just that - preference. My son, like you, prefers the original format. But the AGS101 came at the end of the GBA cycle and there weren't all that many made. Plus add in the fact that kids are rough on these things, there's a very finite supply. A small army of screen scavengers doesn't help that situation at all.

BlackBerriesAndThinkPads · Sep 21, 2017

Collecting the parts for my custom GBA.

Are there any cheaper sources for the 5-Level Brightness Ribbon Cable or is it only lee_chan1985 on ebay at $42 USD?

Also, is either the 32 pin or 40 pin GBA preferred? Is there any specific motherboard revision of the original GBA that is superior? I have a bunch of original donor GBAs to choose from.

Cheers,

pelago · Sep 22, 2017

Is there any version of the variable brightness cable which "remembers" the previous used brightness level when you power off/on? Or if not that, at least one in which you can pre-set (maybe with dip switches or soldering links) a preferred initial brightness level that it would use on power on?

MNiceGuy · Sep 25, 2017

BlackBerriesAndThinkPads said:
Collecting the parts for my custom GBA.

Are there any cheaper sources for the 5-Level Brightness Ribbon Cable or is it only lee_chan1985 on ebay at $42 USD?

Also, is either the 32 pin or 40 pin GBA preferred? Is there any specific motherboard revision of the original GBA that is superior? I have a bunch of original donor GBAs to choose from.

Cheers,

For the backlight mod, there are two motherboards for the GBA. The original 40-pin and the later 32-pin. The 32-pin is generally more desirable because it requires no modification beyond optionally soldering the LCD adapter ribbon's power to a given point on the mainboard. You will want a Type-B (white tab) screen for a 32-pin GBA.

The 40-pin can produce image quality on par with the 32-pin counterpart but there is a little extra work needed. Here are the most popular methods today:

1. 40-pin Type-A LCD adapter + Jumper

The jumper, connecting a specific solder pad to ground, corrects the washed out image. The downside is the LCD voltage is still not exactly as it should be and many report ghosting.

2. 40-pin Type-B LCD adapter

The supposed solution to the problem above. The issue with these adapters is they bypass the LCD potentiometer on the GBA mainboard; removing the ability to fine-tune voltage. If your screen happens to work well with the voltage supplied by the Type-B adapter then this is a very easy solution. If your screen doesn't like this voltage (i.e. washed out color, 'interlacing') then you have no easy way to adjust and correct it.

3. 40-pin Type-A LCD adapter + Mainboard Component Removal + Jumper

This sounds like a lot of work but it's really nothing serious. This requires the removal of certain components from the mainboard and the addition of a small jumper. Then, a 40-pin Type-A cable is used as it would be with the first method above. The advantage here is the GBA potentiometer is still in-circuit and can be used to fine-tune the new screen. This is my go-to method.

pelago said:
Is there any version of the variable brightness cable which "remembers" the previous used brightness level when you power off/on? Or if not that, at least one in which you can pre-set (maybe with dip switches or soldering links) a preferred initial brightness level that it would use on power on?

There are cables in each of the three varieties (32-pin, 40-pin A, 40-pin B) which have a physical brightness switch built-in. Every implementation of this that I have seen mounts the switch in such a way that it can be accessed from the battery compartment. This would leave the brightness setting at whatever it was when the system was last powered off. I've never used one so I can't speak to brightness levels in the different switch positions.

Personally, I just use 'standard' cables with the power wire soldered on DA1. This gives what I consider acceptable brightness.

pelago · Sep 26, 2017

MNiceGuy said:
There are cables in each of the three varieties (32-pin, 40-pin A, 40-pin B) which have a physical brightness switch built-in. Every implementation of this that I have seen mounts the switch in such a way that it can be accessed from the battery compartment. This would leave the brightness setting at whatever it was when the system was last powered off. I've never used one so I can't speak to brightness levels in the different switch positions.

Personally, I just use 'standard' cables with the power wire soldered on DA1. This gives what I consider acceptable brightness.

Thanks, although I meant the cables that you can change the brightness easily without reaching into the battery compartment, e.g. holding Select and pressing L. I guess if there was a possibility to have a brightness slider easily accessible on the side of the GBA, that would be good too, even if it no longer looked stock.

MNiceGuy · Sep 27, 2017

pelago said:
Thanks, although I meant the cables that you can change the brightness easily without reaching into the battery compartment, e.g. holding Select and pressing L. I guess if there was a possibility to have a brightness slider easily accessible on the side of the GBA, that would be good too, even if it no longer looked stock.

Of course this is a matter of opinion but I find the backlight brightness when using a normal ribbon jumpered to DA1 (or equivalent) to be more than adequate. I considered switching adapters to an adjustable version but I just can't convince myself I'd actually use that feature.

pelago · Sep 28, 2017

MNiceGuy said:
Of course this is a matter of opinion but I find the backlight brightness when using a normal ribbon jumpered to DA1 (or equivalent) to be more than adequate. I considered switching adapters to an adjustable version but I just can't convince myself I'd actually use that feature.

Well, it's useful for when you move your GBA between bright environments and dark ones, but I agree it isn't essential.

eldontyrell · Oct 2, 2017

I modified another GBA today.
Although I didn't connect P1 to DA1 (unlike my first modded one). Brightness seems a little bit low, but it seems perfectly usable to my eyes.
Maybe power consumption will be better as well ?
I had to connect 103 to gnd however, to enhance contrast.

LuCraftStudios · Oct 4, 2017

Hello everyone,
does anyone know, how you can distinguish a original GBA SP AGS 101 display from a aftermarket chinese one?

MNiceGuy · Oct 5, 2017

LuCraftStudios said:
Hello everyone,
does anyone know, how you can distinguish a original GBA SP AGS 101 display from a aftermarket chinese one?

That's actually a very good question. I would like to know myself.

Personally I think the quality of the Chinese screens is quite good. On RetroRGB, there's mention that the aftermarket screen "isn't nearly as good" and in my experience I can't agree with that assessment. I'm of the belief that the aftermarket screen the author experienced was not properly adjusted and was misbehaving (poor contrast, interlacing, etc.) as a result.

If you want to track down an original screen that's certainly an option but I wouldn't completely disregard the aftermarket options either.

LuCraftStudios · Oct 5, 2017

MNiceGuy said:
That's actually a very good question. I would like to know myself.

Personally I think the quality of the Chinese screens is quite good. On RetroRGB, there's mention that the aftermarket screen "isn't nearly as good" and in my experience I can't agree with that assessment. I'm of the belief that the aftermarket screen the author experienced was not properly adjusted and was misbehaving (poor contrast, interlacing, etc.) as a result.

If you want to track down an original screen that's certainly an option but I wouldn't completely disregard the aftermarket options either.

OK thank you for you answer

Sajun · Dec 4, 2017

Hey all!

So I recently completed my first mod on a 40 pin GBA to a white ribbon SP screen with a ribbon cable purchased on the Retro Modding website.

I had a slew of problems but managed to figure them all out. However, I'm having one last issue now that I finally have the thing working. When I turn the screen on, no matter what game, I have issues with vertical scrolling. Anytime I have movement vertically it seems to have issues refreshing, so it looks choppy. This is particularly problematic in games that are isometric, such as Final Fantasy Tactics, and the issue renders it nearly unplayable.

Adjusting the potentiometer seems to do nothing. Turning it slowly either way gets super bright and then less-bright, and ranges in between those two settings, but never fixes the vertical scrolling issues.

On top of the vertical scrolling problem the screen is also kind of washed out, as if the contrast is too bright. Where the screen should be black along the edges when using a GBC game, or when the background should be black on a GBA game, it's instead grey-ish.

Can anyone make any suggestions? I've seen mention of soldering another wire between REVC and GND, as well as a few alternatives to this, but has anyone who's suffered from the same issue tried this potential solution with success?

Any help would be amazing. Thanks!

slaphappygamer · Dec 4, 2017

BlackBerriesAndThinkPads said:
Collecting the parts for my custom GBA.

Are there any cheaper sources for the 5-Level Brightness Ribbon Cable or is it only lee_chan1985 on ebay at $42 USD?

Also, is either the 32 pin or 40 pin GBA preferred? Is there any specific motherboard revision of the original GBA that is superior? I have a bunch of original donor GBAs to choose from.

Cheers,

This is the same adapter I installed. The price was worth it to me. I'm pretty sure it's look the exact same wether it's in a 32 pin or 40 pin motherboard. I notice the gba cycles through the brightness levels each time I power on the unit.

MNiceGuy · Dec 4, 2017

Sajun said:
Hey all!

So I recently completed my first mod on a 40 pin GBA to a white ribbon SP screen with a ribbon cable purchased on the Retro Modding website.

I had a slew of problems but managed to figure them all out. However, I'm having one last issue now that I finally have the thing working. When I turn the screen on, no matter what game, I have issues with vertical scrolling. Anytime I have movement vertically it seems to have issues refreshing, so it looks choppy. This is particularly problematic in games that are isometric, such as Final Fantasy Tactics, and the issue renders it nearly unplayable.

Adjusting the potentiometer seems to do nothing. Turning it slowly either way gets super bright and then less-bright, and ranges in between those two settings, but never fixes the vertical scrolling issues.

On top of the vertical scrolling problem the screen is also kind of washed out, as if the contrast is too bright. Where the screen should be black along the edges when using a GBC game, or when the background should be black on a GBA game, it's instead grey-ish.

Can anyone make any suggestions? I've seen mention of soldering another wire between REVC and GND, as well as a few alternatives to this, but has anyone who's suffered from the same issue tried this potential solution with success?

Any help would be amazing. Thanks!

Which ribbon did you use? Type-A or Type-B? Could you explain the steps you took to complete you mod?

Hardware GBA Backlight! (AGB-001)

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