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PostPosted: Wed Jun 14, 2017 10:37 pm 
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#1- you'll pay a significant overhead for shipping if you get it from digikey.


Digikey has free shipping if you mail them a check. :)


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PostPosted: Thu Jun 15, 2017 3:24 pm 
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I went to try and remove the diode, so I took the other side of the case off of the board, but there were no solder balls or anything, which doesn't really surprise me. However, I poked it with a screwdriver, and it was so fried it disintegrated. Unfortunately, I can't even see how it was originally connected because the board there is so burnt. Could I just put two solder balls on each side, then press the new diode on? I didn't get to test to see if the Gameboy Color works yet.


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PostPosted: Thu Jun 15, 2017 3:41 pm 
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Just do a continuity meter between the two pads. If it's not conductive, then it's not conductive.

On the other hand, if the PCB is substantially burnt, you might need to check if any other traces are damaged.


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PostPosted: Tue Jun 20, 2017 6:42 pm 
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Uh, a bit of an update (sort of), but even without the diode in place, it still doesn't work. Something I'd like to have explained to me, is how is this supposed to work without the diode? I'm confused as to how electricity passing through the diode causes the Gameboy not to work. (I know I have much less knowledge about electricity than most people here.)


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PostPosted: Tue Jun 20, 2017 7:11 pm 
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Espozo wrote:
Uh, a bit of an update (sort of), but even without the diode in place, it still doesn't work.
Unfortunately, that means that the diode is "merely" collateral damage, not the reason it's not working.

The next most likely culpable victim is the voltage regulator (boost converter) U5. It supposedly takes the 3V from the batteries, and boosts it to 5V, -15V, and 13.6V. The only other things that I see connected to the unregulated battery voltage is the power LED D4 (does it still light when you turn it on? The power LED should light as long as both battery voltage and 5V is present and the battery voltage is high enough.)

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Something I'd like to have explained to me, is how is this supposed to work without the diode?
The diode is there to protect the rest of the circuit against a negative voltage. Normally it shouldn't be doing anything.

However, now that it's burned up, if it is doing something, then it's shorting out the batteries. Hence no power could get to the voltage regulator.


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PostPosted: Thu Jun 22, 2017 3:36 pm 
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You can test most of the game boy carefully using a 5V regulated power supply, and powering the 5V section manually (bypass the voltage regulator). I'm not sure if you'd hear sound in this case, but you'd at least be able to look for wiggling address lines on the cartridge connector.


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PostPosted: Thu Jun 22, 2017 6:39 pm 
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Oh, there's the other part that I couldn't find that runs directly off the battery voltage: the audio amplifier IC.

As far as I can tell, the CPU should only need the 5V and 3V rails to be good (there's an LDO regulator deriving 3.3V from the 5V rail: U7/"RN5RT33A")

The LCD should be the only part that needs all 3 voltage rails.

(It wasn't hard for me to find the schematic. Just search for "gameboy_color_service_manual.pdf". )


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PostPosted: Thu Jun 22, 2017 10:54 pm 
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lidnariq wrote:
Oh, there's the other part that I couldn't find that runs directly off the battery voltage: the audio amplifier IC.

As far as I can tell, the CPU should only need the 5V and 3V rails to be good (there's an LDO regulator deriving 3.3V from the 5V rail: U7/"RN5RT33A")

The LCD should be the only part that needs all 3 voltage rails.

(It wasn't hard for me to find the schematic. Just search for "gameboy_color_service_manual.pdf". )


I don't think the 3V rail is used at all by the logic, what is it used for?


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PostPosted: Thu Jun 22, 2017 11:31 pm 
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Good question. It is connected to the package, though. 3V is supposedly also used by the SRAM inside the GBC, so maybe it's just for interfacing to that?


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