Hi, i recently bought a DMG gameboy in hopes of modding it. When it arrived, I realized it had a problem with the contrast. Its constantly changing, in sort of a flickering way. Messing with the wheel makes it jump around more, and doing so little as applying light pressure on the wheel makes it change around more as well. Any fix for this? Thanks!
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CA
When I see those symptoms it usually means that the brightness potentiometer is buggered.
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friendofmegaman wrote:
When I see those symptoms it usually means that the brightness potentiometer is buggered.
Do you think ill have to replace the wheel?
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CA
Ansel wrote:
friendofmegaman wrote:When I see those symptoms it usually means that the brightness potentiometer is buggered.
Do you think ill have to replace the wheel?
I would replace it, yes. Make sure it's a compatible potentiometer. If I remember it correctly it's a 30k pot, 16mm. It's through hole, so relatively easy to de-solder, but be careful as the screen is close. In fact I think you're gonna have to lift that white frame around the LCD.
I also remember I was having hard times finding exactly 30k, but you can put 50k or 20k, it will work but well be under or over "sensitive" so to speak.
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Spookane, Warshington
I think I remember something similar happening to me when I had tightened the screws too much. The contrast only changed for me when I applied pressure to the buttons though, and not just by itself.
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NC in the US of America
friendofmegaman wrote:
but you can put 50k or 20k, it will work but well be under or over "sensitive" so to speak.
Which is under and which is over?
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CA
SketchMan3 wrote:
friendofmegaman wrote:but you can put 50k or 20k, it will work but well be under or over "sensitive" so to speak.
Which is under and which is over?
Oh this was merely a metaphor. You see if the original pot is 30k, then when it's on 0 Ohm position the screen is white, on 30k - black. Now if you put 20k I it will never be fully black as if it was on 30k, therefore it's under-sensitive - because you turn the wheel the same distance but you achieve smaller resistance (20k, as opposed to 30k).
Let's apply this logic in reverse. If you're having a 50k the 2/3 way through the turn of the wheel you already reach 30k therefore your screen will turn black faster. This is what I meant by over-sensitive. Again = same turn of the wheel but larger resistance.
I admit it was a bad metaphor. Just discard it an use any of those, or better find 30k and be happy.
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Connecticut
In addition, you should replace your capacitors. They're past their shelf life, very cheap, and do worlds of wonders for all sorts of problems.
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NC in the US of America
friendofmegaman wrote:
SketchMan3 wrote:Which is under and which is over?
Oh this was merely a metaphor. You see if the original pot is 30k, then when it's on 0 Ohm position the screen is white, on 30k - black. Now if you put 20k I it will never be fully black as if it was on 30k, therefore it's under-sensitive - because you turn the wheel the same distance but you achieve smaller resistance (20k, as opposed to 30k).
Let's apply this logic in reverse. If you're having a 50k the 2/3 way through the turn of the wheel you already reach 30k therefore your screen will turn black faster. This is what I meant by over-sensitive. Again = same turn of the wheel but larger resistance.
I admit it was a bad metaphor. Just discard it an use any of those, or better find 30k and be happy.
You explained it perfectly. Thanks
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DropMontage wrote:
In addition, you should replace your capacitors. They're past their shelf life, very cheap, and do worlds of wonders for all sorts of problems.
I haven't heard this before. What capacitors do you replace, and what does it fix (or improve)?
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Connecticut
Bad capacitors can contribute to a lot of different problems, flickering screens, poor contrast control, poor audio, etc. There are 17 capacitors in a DMG-01, you can purchase these in pre-made kits from people like Kitsch, or you can grab them from Mouser or other wholesale retailers. I've been restoring and modding vintage electronics for around 10 years now, and capacitors are always where I start. It resolves most issues and usually brings the unit back to like new working conditions. There is really no reason not to since they're so cheap. The style you would be looking for are Aluminum electrolytic capacitors-leaded, the capacitance you need will be Qty 4 100uF at 10V, Qty 2 100uF at 6.3V, Qty 1 33uF at 25V, Qty 7 1uF at 50V, Qty 1 10uF at 25V, and Qty 2 10uF at 16V. I generally buy the smallest size I can find, as long as it meets the capacitance. I also buy mostly Panasonic, and always RoHS compliant. This will require basic soldering/desoldering skills. In short, this should bring your gameboy back to its prime, while also insuring that any mods you put in will recieve the appropriate charge needed.
PS-When installing, most capacitance requirements are written both on the board and the cap you remove, with a note of where the positive lead goes. Positive leads are the longer leads on a cap, but dont worry if you've already trimmed them, as the negative lead of a capacitor is marked on the body.
Last edited by DropMontage (Aug 24, 2015 4:04 pm)