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Discussion about software development for the old-school Gameboys, ranging from the "Gray brick" to Gameboy Color
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#1 2009-06-15 16:40:00

eptheca
New member
Registered: 2009-06-15
Posts: 3

DMG potentiometers

Hi,
I'm replacing the contrast and volume pots on the DMG for a case mod.
Does anybody (you) have any suggestions for pots?
On the PCB and in the schematics it says 30K for the contrast pot, but when I test it it's about 17. Any experience on this?
The volume pot says 2x10 on the PCB, and I guess thats for stereo, is that correct? Also any recomendations here?

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#2 2009-06-17 17:11:45

nitro2k01
Administrator
Registered: 2008-02-22
Posts: 245

Re: DMG potentiometers

The 17k value is no error; you're measuring the resistance of any other component that is connected in parallell with the pot, which brings it down. Use 30k. Any 30k resistor should do. If you can't find a 30k pot, 33k or even 47k or 50k should work fine too. (Those are standard values and probably easier to find)
Where on the board does it say 2*10k for the volume pot? According to the documentation I'll link below, the value is supposed to be 1k. Any value up to 10k, or mabe even a little more should work. Just make sure it's a stereo pot. You could also make your own amplifier circuit. (Recommended, especially if you want a more powerful speaker)

You might find this useful:
http://gameboygenius.8bitcollective.com … Schematics


Blog: Gameboy Genius
"A journey of a thousand miles begins with one small step"
Old Chinese Proverb

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#3 2009-06-19 09:39:37

eptheca
New member
Registered: 2009-06-15
Posts: 3

Re: DMG potentiometers

Thanks for direction nitro,
The pots where desoldered from the PCB when I tested them, I tested two and they gave the same value. I have bought a 50K one, hope it will work.
For the volume pot it says 10Kx2 on the left side of the pot, right above the edge of the cart socket, and when you remove the pot it says VR1 10Kx2 underneath. I know it says 1K in the schematics, but when I tested it, it is logaritmic 10K. I dont understand schematics, and therefor dont trust them totally. For example for the buttons it says P10-P15, but really its either pins 13-18 or 4-9 as you can see on my image http://www.flickr.com/photos/25935372@N06/3553195775/

Bought a stereo pot from https://www1.elfa.se/elfa~se_sv/b2b/start.do
called ALPS RK09, art.nr. 64-125-14
it has 6 pins, and I dont know which is which yet, do you know anything about this type?

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#4 2009-12-12 10:29:14

NeX
New member
Registered: 2009-12-12
Posts: 5

Re: DMG potentiometers

I have found a few problems with the wiring diagrams for the gameboy, I emailed the guy who made them but he hasn't replied.

i replaced the pot for the screen with a 25k pot, and all is well with that
i used a stereo 1k pot for the sound and it didn't work at all, after mesuring it, it seems to be a 10k pot except it has a minimum resistance of 10k and a maximum of 20k

either way i have ordered some 10k pots, and if they need a base resistance of 10k i will just put a resistor in line.

hope that helps

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