I have done bivert mods on two gameboys and both of them have the same issue. Only two of the 4 shades of grey will display.  I was just using some off the shelf hex inverter chip I had laying around, but I figured maybe that was causing the problem so I bought some of the hand held legend bivert boards and I get the exact same result. Also running my finger around the bivert board while it's booted causes graphical glitches. It seems like it's maybe a problem with some connections somewhere, but I'm not sure where to check. Any help would be appreciated!

Here's some pictures:

This is what I get:

Here's what it should look like (GBA SP):

Here is what it should look like (inverted, non biverted DMG):

Last edited by catskull (August 1, 2016 4:17 am)

Can we get a photo of your install?
Is it grounded with the extra wire?

Last edited by catskull (August 1, 2016 4:18 am)

Oddly enough, I cannot see your last three photos.

Images fixed. I tried to go off google photos instead of imgur since imgur is user hostile now.

Anyways, I figured it out! Though I'm kind of curious what you have to say jazz before I reveal the issue! I'll give you a hint: it had nothing to do with the HHL installation.

My problem was the method I used to install the bivert. I cut the traces between the LCD connector and that little header thing, but in the wrong place. Here's how I cut it:

As you can see, I cut it ABOVE the via, not below. If you look at the back of the board you can see why this is a problem:

The yellow line is the trace coming off the via to the CPU pin. So the header pin I soldered the chip to wasn't contacting the CPU pin at all.

The vias on my board are not plugged like they are in that picture, so soldering a wire to the via didn't work. Instead I just soldered a peice of wire wrap from the cpu pin to the other side of the header pin, and voila! It worked perfectly.

Now time to go fix every other DMG I own....

As a side note, what the heck is the deal with this HHL bivert board needing the wire for ground? There's a ground on the LCD board right on the end with a huge blob you could easily bridge. What's the deal with that? Kind of makes me want to make my own bivert board with only a 2 gate chip. I really like the design of the HHL board otherwise.

catskull wrote:

The yellow line is the trace coming off the via to the CPU pin. So the header pin I soldered the chip to wasn't contacting the CPU pin at all.

Yes. And also, if you don't also cut below the via, you're connecting an output to an output! The deadly sin. (At least potentially deadly to the chip outputs although it probably didn't cause permanent damage in this case.)

catskull wrote:

As a side note, what the heck is the deal with this HHL bivert board needing the wire for ground? There's a ground on the LCD board right on the end with a huge blob you could easily bridge. What's the deal with that? Kind of makes me want to make my own bivert board with only a 2 gate chip. I really like the design of the HHL board otherwise.

Or, you could use a smaller inverter chip and use one of the grounds in the 6 pin array. Hmm!

Those easy chips are such a pain. Last one I did I just tore the chip off and wired it in, cause it kept missing the points.

nitro2k01 wrote:
catskull wrote:

The yellow line is the trace coming off the via to the CPU pin. So the header pin I soldered the chip to wasn't contacting the CPU pin at all.

Yes. And also, if you don't also cut below the via, you're connecting an output to an output! The deadly sin. (At least potentially deadly to the chip outputs although it probably didn't cause permanent damage in this case.)

Wait how do you figure? It looks to me like that pad wasn't connected to anything.

Oh by the way, here's the rom I was using to test with: https://drive.google.com/open?id=0B2JWZ … VhSTW1TTWM

Fredrik Brundin made it for me, what a nice guy!

What I meant was that while the mod was incorrectly installed, this problem existed and could have damaged the CPU or inverter (but probably didn't). Although thinking about it, I forgot this mod board has you lift the pin, so the inverter output would never have been connected to the CPU output unless there's an excessive blob of solder that touches the pad. Which also means that you shouldn't really have to cut the traces at all if you're careful when installing the board.

I see. Yeah the traces were cut originally when I didn't use the hhl board. I actually like the non destructive nature of the hhl board, especially considering its only a few dollars.