irony7
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Questions about decoupling:

1) I've added a 470uf electrolytic capacitors over what I read as the 5v regulated power and ground, using the connections that come up through the CPU board, as shown in the following image:

The connections are, as I read the voltages from the board and from top to bottom:  unregulated voltage from batteries, ground, -19v to LCD,  regulated 5v from powerboard. The red lead is positive from the electrolytic capacitor (seen to the right and below the main board), the black is negative.

Question is, have I done the connections correctly?  There is still a very slight hiss (varies in pitch and intensity when heard through the headphone jack with the sound pot turned way down). 

2) This is a big ass cap. Where it's installed is the only place it was possible to fit it. 

Questions are, are there physically smaller caps available?  And does the length of the connections due to placement compromise the effectiveness of the mod?

Thanks in advance for your help, guys.

Last edited by irony7 (May 31, 2017 8:44 pm)

Jazzmarazz
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Michigan

Looks correct.
There is only so much you can do , friend. The gameboy is not a perfect beast, but a little hiss is to be expected. If you want it gone, then emulate.
As for your questions, the larger the capacitance, the Marge the physical size generally speaking. 
A pro-sound mod will also help a tad.

The static is life. The static is love. Embrace the static.

nitro2k01
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Sweeeeeeden

A prosound mod is the single most effective thing you can do to reduce noise. If you're fine with not using this DMG directly with headphones (only for recording or through a mixer) and don't want to modify the case, you could prosound it through the existing jack.

irony7
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There will be a prepot prosound mod also in this machine. It's actually a complete internal swap (necessary due to power problems using flash cart and backlight) , replacing the boards from a CPU revision 05 model with CPU revision 08 boards. The decoupling is something I wanted to try, since the machine was open anyway.

It does seem to have less noise now through the headphones. Exciting to hear how it is through the prosound mod.

darenager
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I am looking into ways to reduce noise on dmgs too, thinking about swapping out the electrolytic caps for new ones, and trying to reduce the cpu noise and power supply noise using more bypass caps. I prosound all of mine, and whilst it certainly helps it does not get rid of the whines and clock noise, I believe that these can be reduced though, backlight and flash carts do make the noise worse.

I'll be interested to hear how it sounds with the 470uf and prosound.

irony7
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There is still some slight noise through the pre-pot Prosound jack, but it is less in comparison other non-decoupled Prosound mods I've done. Perhaps doing a conplete cap replacement will help reduce noise further.

Last edited by irony7 (Jun 2, 2017 9:15 pm)