GB DMG-001 bivert only has 1-bit color?!

romanaOne

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I'm using one of these:
https://handheldlegend.com/products/game-boy-bivert-biversion-module

There are no greys, each dot on the screen is either on or off. You can's see the sky on the Tetris title screen.

I have double and triple checked my soldering (there's not that much to solder!) and I can't figure out what I did.
I'm worried that I may have overheated the pins 6 and 7 on the screen connector to lift them off the board. Maybe this damaged something connected to them?

Continuity tester shows there is no solder bridge between the pins 6 and 7. I also tested the solder points on the bivert board and they are all good. I've tried swapping top halves and the screen works perfectly on another bivert-modded GB so it is not a problem with the screen or cable.

Removing the the bivert board (and rotating the polarization film back to the old position) still gives 1-bit color. So there is something wrong with the motherboard. Any ideas? This board is huge and relatively easy to work on compared to later GB Pocket, Color models. If only I know what to replace.....
 

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romanaOne

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The z80 is a 8bit processor. You likely screen burned the LCD with that chip.

huh? Lots of people use this chip and I've never heard of it "burning the LCD."

Also, the LCD works fine in another DMG-001 Gameboy using the same bivert chip.

I've measured the resistance of all soldered connections between pins 6,7 on the white screen connector and pins 1,2,3,4, Vcc, and GND. All are <<1 ohm. It is not the typical bivert problem of bad solder connections: either the chip is bad or there are broken traces on the DMG motherboard. (The HHL bivert board covers up a few square cm of the DMG motherboard.) I'll pick up some 74HC04 hex inverters and try again w/o the HHL board. So much for doing it the easy way.
 

how_do_i_do_that

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The LCD has grey scale, lets call it level 0-7. 0 for off and 7 for the solid black state. That chip seems to put the all the LCD controller's pixels to the level 7 at all times when on.

I was making an observation on what that modchip did. I believe there was a person a few years back did the same thing.

I should have edited the last post to say it was an observation, not a really helpful post or critique on what you did.
 

romanaOne

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Mystery solved. I got curious and removed the two screws holding the board to the bottom case. This made it possible to see the back of the board. I discovered the trace going from pin 3 to the DMG cpu was broken, probably from excessive soldering to try to get this stupid board to work.

Anyhoo, a bit of wire jumping over the bad trace and a new 74HC04 got it working. So much for the easy way. I wonder what people find so scary about soldering to a chip worth less than a dollar?
 

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