Faulty Gameboy DMG cartridge reader question and others..

[lpoolm]

So I bought a few faulty Gameboys (didn't know the seller swapped all the bad bits into these) but I am determined to fix! They all seem to have had battery damage.

My first question is I have got two of them going but neither read games, neither show the Nintendo logo just a corrupted version. Both had a lot of corrosion, I have cleaned and cleaned and they look ok but still not loading games.

Am I right in thinking a corrupted Nintendo logo is down to the cartridge reader? If so will look at swapping them out. If not do not want to waste my time.

My last one the worst, I have gotten it to the stage that it turns on as in the screen looks to activate but nothing else happens, no logo, contrast wheel doesn't work. I have been checking for issues and shorts, the only issue I currently find is on the C6 capacitor, I have no reading but on the other (almost) working I do get a reading. However I have a few donor boards and everyone I have taken off and put on to this board gives me no reading which makes me think it could be another issue?

Any pointers would be great. Thanks

 

[Deleted member 668561]

if there is no issue with the cpu itself it can be an sram issue, gb has 16k iirc 8k main ram, and 8k display ram, also seems like a decoupling cap 10uf, also the dmg's have use a negative voltage to drive lcd contrast, iirc a max of -18vdc

if replacing the ram doesnt work or the cartridge port, it could be the SOC is internally bad, if you have an oscilliscope or logic analyzer you could probe the clock, read/write, and the buses, this would be pretty straightforward

unless the actual pcb itself has gone bad