/documents/gameboy mods/GBTransfererPSUmod:
EMS Transferrer I: "PSU Mod"
Ever have a problem with the Transferer? HAH O.K. Do I even need to ask that question?
*Laughs* Well I'm talking about one of two problems... maybe even more.
1. When transferring .sav files from your GameBoy Camera, the images always turn out with white vertical lines
2. When flashing a .GB file to a cart, the Transferer Software freezes in the middle of the flashing process.
Well if either of these issues happen to you, I have some good news for you. This EXTREMELY EASY Modification will fix those two issues. I have yet to see the end of the problems this has fixed.
Let me start of by providing a little bit of information on Power Supply (PSU) Decoupling
(as taken from wiki)
"One common kind of decoupling is of a powered circuit from signals in the power supply. Sometimes for various reasons a power supply supplies an AC signal superimposed on the DC power line. Such a signal is often undesirable in the powered circuit. A decoupling capacitor can prevent the powered circuit from seeing that signal, thus decoupling it from that aspect of the power supply circuit."
"To decouple a sub-circuit from AC signals or voltage spikes on a power supply or other line, a bypass capacitor is often used. A bypass capacitor is one whose job is to shunt energy from those signals or transients past the sub-circuit to be decoupled, right to the return path. For a power supply line, a bypass capacitor from the supply voltage line to the power supply return (ground) would be used."
The other day I was talking with a friend from 8bc.org about issues that I was having my GameBoy Camera Pictures. They kept having these white vertical lines after I dumped them onto my pc from the GameBoy. He being older and wiser recommended I try using a 9V battery instead of the wall wart. So I wired up a little 2.5mm -> 9V Clip adapter and tried it again... Since batteries are just an energy cell, they are the best form of a clean power source. Sadly batteries never last long. Anyways... I retransferred the images and BINGO!!
He was right! Now I know that US Electricity standards are a lot better than that, so I opened up the Transferer to see if the problem could be found locally.
And so here is the Transferers power supply stock
I opened up my Transferer and was surprised to see that who ever designed the Transferer didn't use decoupling caps on the power supply! I mean I thought that was just industry standard!!! Guess not!?!?!
Since I didn't have a scope at home, I couldn't look at my supply signal to see how noisy it was. I plan to do this next time I'm using the scope at work (I'll have pictures soon of the before and after). So I just tack soldered in a .01 on the input of the 5 volt regular pin (7805) and a .1 to the output of the regulator. I then tried the same transfer with an image.
The Results... NO VERTICAL LINES! On top of that I tried making some carts to see if I could get the program to crash... so far I haven't been successful. Which is good! If the main issue with the Transferer was a crappy supply voltage going to the PIC, I hope this will fix many of the issues people seem to be having when attempting to flash a cart.
Here is a visual representation of what I'm talking about.
[before]
[after]
So... now it's your turn!!!
***Disclaimer: I am not liable for any damage caused to you or your GB Transferer due to human error. Discharge your body before working on anything electronic and above all, be careful and use common sense. This mod was done based of theory and should work and if don't properly will not harm your Transferer in any way.***
Parts:
Solder
Small Screw Driver (Phillips head)
(1) .01 uF (10nF) cap (Panasonic poly cap from digikey.com )
(1) .1 uF (100nF) cap (Panasonic poly cap from digikey.com )
Side cutters
Needle Nose Pliers
patience
care
Procedure:
Step 1: Opening the Transferer
Locate the 4 screws on the back of the Transferer. Then remove them.
Step 2 Remove Circuit Board from plastic enclosure
Open the chassis. There is nothing holding the circuit in the chassis once the back has been removed so it should be easily removed. Place the circuit board on a clean surface and observe. With the DB25 connecter (part that hooks to your computer) towards you, you will find the main portion of the power supply in the lower left hand corner. The power switch is in the middle right hand side. The large black object with 3 pins sticking out of it label "7805" is what we will be paying most attention to. (click image for highlighted areas).
It is known as a 5Vdc regulator. Itss job is to take the incoming 9Vdc signal and drop it down to 5Vdc. It basically dissipates the power via Heat (hense the large piece of metal attached to it). In order from left to right the pinout of the 7805 is: In - Ground - Out
Now Turn the board over and relocate the Power Switch and the Regulator.
Remember that everything is now backwards so the pin out will be (as you are looking at it from left to right) : Out - Ground - In
Here is the updated schematic post modification. I have marked the changes in RED
And here is where, on the bottom (solder) side of the board the parts will go:
Step 3: Prep your Caps!!
Chances are, when you get your caps, They wont be spaced correctly to solder on to the bottom of the board. The leads will also probably be too long. So you will want to first use your needle nose to bend the leads in , then back down/out to get them closer together.
Then you will want to cut them to a workable length. They should then look something
like this when you are done.
Step 4. Solder your caps to their respectable places on the PCB.
I add a little bit of solder to each point that I will be soldering to on the PCB. I then Tin my Cap leads. This ensure a quick bond with the least amount of head. It will make for a cleaner and better joint.
The .1uF should go on the regular here...
And the .01uF should go on the power switch here...
My reasoning for not putting both caps on the regulator are for esthetics only. If you can solder both caps to the top side of the regulator, by all means go ahead, just remember, that if you bridge the leads of the regulator together in any way they will short and fry the regulator. Doing it where I have done it works, and keeps it looking clean and easy to do.
If you follow the traces back from the switch to the supply you will see why I chose the switch for a soldering point.
Step 5 Close it back up!
Once the two caps are in place you can now close the Transferer up. Be sure that the caps are laying flush with the pcb to allow room for the pcb to fit inside the chassis. If you want to make sure the cap doesn't move around you could hot glue it once it's been soldered in. it will also double as an insulator from the rest of the board.
CONGRATS! YOU DID IT!
Double and triple check to make sure you didn't short anything while soldering. It can easily be done.
If done correctly the Transferer should power up like normal. Try flashing a cart. If you previously has issues with it freezing in the process of flashing, the theory so far is that it should stop doing that. And if you are transferring pictures from the GameBoy Camera to your PC, you should now have clear (as good as the GB Cam can do for clear!) pictures!
If something isn't making sense, drop me an email if you have any questions. That way I can re-word things to make it easier for you.
If you are uncomfortable with doing this, I can do the mod for you for $25 + shipping.
Enjoy!
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