3ndymion
Offline
NYC

Here is something that I think many people here would likely need.  It is possible to restore your Gameboy volume & LCD potentiometers to brand new condition, & I will show you how I figured it out, & how I did it.  For the longest time, I've had bad spots in the volume & LCD contrast knobs that would not only produce completely dead spots, but would always cause static as well.  It was so annoying!!!  Well, no more.  Let's begin.


ANALYSIS

I have an old Gameboy that I accidently ripped the LCD ribbon cable off the board when trying to put in a backlight about a year ago.  I used that one for parts.  I unsoldered the volume potentiometer off the board, & decided to test it.  Its minimum range seems to be around 20 ohms of resistance.

Its maximum range seems to be close to 10K ohms.

Here, you can see where it sat on the board.  The empty spot is labeled "VR1 10Kx2".

A wider shot.

The potentiometer with the volume knob still on it.

Flipped around.

Now with the wheel taken off.

Now completely disassembled.
NOTE:  This seems to be a newer wheel.  I've seen a couple of others that don't have the detachable yellow plastic piece like this one does.

Flipped around.

This piece should be able to be cleaned with a pencil eraser.  That would likely eliminate any dead spots & fix any type of contact problems.

So, from what I see so far, it looks like the wheel spins freely on the shaft.  The top of the shaft has been mushroomed down over the wheel to keep the wheel pressed down at all times.  This way, it can stay pressed down on the contacts & spin freely at the same time.

3ndymion
Offline
NYC

REPAIR

Now, I'm going to try this on my personal Gameboy.  I'm pretty worried though.  I'll have to pry in the mushroomed part of the shaft to get the wheel off, but how will I get the wheel back on afterwards???  I'll try using a staple.  I'll hold the staple in the center of the shaft while I pry the mushroomed part in with a tiny flathead screwdriver.  That way, I'll hopefully be able to pop the wheel back on afterwards & push the metal back down over the wheel to hold it down again.

OK, after quite a bit of effort, I bent the metal in & was able to pop the wheel off.

Here's a close-up of the contact surface area.  I can see a couple of marks on there that were likely the cause of my problems.

All cleaned up with a pencil eraser.  This should have it working like brand new again.

!!!  I really mangled that metal.  The wheel popped back on, but it's not holding!!!  Now I'm a bit desperate.  This is my personal Gameboy, & I don't wanna lose it.  I'll try a couple of things...

Method: Hold it down with a blob of solder.  Result = FAIL
Method: Jam it full of Krazy Glue to hold it down.  Result = FAIL

It looks like I'm down one more Gameboy now.  At this point, I have nothing to lose.  I can only think of one more thing...

Method: Drill out the center completely & use something else to hold the wheel down.

Well, here we go.  I drilled out the center completely.  It actually drilled through pretty easily.  I noticed something...  the Gameboy screws are about the same size as the hole.  Maybe I can use one of them to hold the wheel down???

The screw fits through the wheel, but very tight.  So I'll screw it all the way down into the wheel & keep screwing.  That should rip some plastic out of the middle.  I'll also jam it down by force a few times to try & rip some more plastic out.  That way, the wheel won't actually screw onto the screw.  Well, not too much anyway.

Now, I'll screw the screw through the hole in the board to open it up a little.  It's a very tight fit, but that's a good thing.  That means it will definitely hold the wheel down at all times.

An underneath shot.

And now, I'll try screwing the wheel back on.  It fits!!!  This is working!!!  The wheel is all the way down now, & it turns too.  It's much harder to turn now, BUT, it turns.  Not only that, it's also hitting the stops at minimum & maximum, just like it should.  That means that it's perfectly aligned.  This is great!!!

Test... & success!!!  It works!!!  This Gameboy has been saved.  Not only that, even though it takes much more force to turn now, the volume wheel works perfect.  It's like brand new again.  No more static & dead spots!!!

3ndymion
Offline
NYC

EXACT & CORRECT PROCEDURE

Now that I've figured out how to do this the right way, I'm going to do this on my other Gameboy, for the LCD contrast potentiometer.  This time, let's follow an exact & correct procedure.

This time, I'm not gonna mess around with the mushroomed part.  Instead, let's just drill right through it.  The fact that it's mushroomed actually works to our advantage here, because that will keep the drill bit centered in the hole & make it easier to drill through.  It's almost like if Nintendo wants us to drill through it.  : P

Use a 1/16" (1.6mm) drill bit.  It's a perfect size, & also the smallest one I could find anyway.

It drilled right through.  It was very easy.

I'll try to spin the wheel on the drill bit too, to try to rip some plastic out the middle.  This drill bit might be too small for that though, but a larger one will probably break the contacts on the back of it.  I'll jam a screw through it later as well.

A close-up.  That dark spot on the top of the arc is likely what was giving me trouble.  Time to clean it off.

All cleaned up.

It's a good idea to unscrew the board & clean the other side to make sure no drill shavings stay down there.

I'll use this screw below the volume knob as a sacrifice to hold down the wheel.

Screw the screw through the board to open up the hole a little.
NOTE:  While screwing the screw through the board, be sure to hold down the outer side of the potentiometer face.  As you're screwing the screw through it, it will start lifting off of the board.  Don't let that happen.  Be sure to hold it down.

A side view.  There won't be any clearance issues with this.

Screw the screw all the way onto the wheel with a screwdriver, & keep screwing to rip some plastic out of the middle.  Try to jam the wheel on & off of the screw as well.  The goal is for the wheel to not hold so tightly to the screw.  It still will to some extent, but it's better to do this to help free it up a little.

Screw the wheel onto the board.  So far, so good.
NOTE:  You don't have to screw the wheel down with all of your force.  The goal is to make sure that the wheel is all the way down, & that it hits the stops at minimum & maximum.  Once it is continously hitting the stops as you turn it back & forth, it's good, & you can rest assured that it's perfectly aligned too.  Also, keep in mind that it will be much harder to turn now.  That's perfectly fine.  It's a good, solid setup now.

Test.  It works.  Very good.  : )

Now, put it all back together...

And this repair is now complete!!!  No more worrying about custom potentiometers that are impossible to source & Gameboys that can't be fixed.  This is like brand new again.  As a side note, if the other Gameboys have these kind of potentiometers on them too, then this should work with those as well.  Well, I hope this helps many people.  Enjoy!!!  big_smile big_smile big_smile

jefftheworld
Offline
Toronto, Ontario, Canada

Awesome, great to see some tutorials like this!

nitro2k01
Offline
Sweeeeeeden

This reminds me of one of the many thing I'm planning to try but probably never will: A voltage regulated contrast circuit which pretty much makes the contrast wheel set and forget. (Normally, the LCD supply voltage varies with the battery health and CPU load, as you can see when LSDj's CPU saving kicks in when the song isn't playing.)

PROTODOME
Offline
UK

Nice!

3ndymion
Offline
NYC

Thanks guys.

nitro2k01 wrote:

This reminds me of one of the many thing I'm planning to try but probably never will: A voltage regulated contrast circuit which pretty much makes the contrast wheel set and forget. (Normally, the LCD supply voltage varies with the battery health and CPU load, as you can see when LSDj's CPU saving kicks in when the song isn't playing.)

That would be a really great idea.  The screen constantly changing contrast when you play & stop can get really annoying.

To add to this guide... I searched & found only 1 potentiometer that was a correct match for the volume pot.  It's available from Radio Shack.  I couldn't find any other stereo pot's like this anywhere on the web.  The one from Radio Shack has a smaller turn knob.  It's very thin, almost like a sheet of paper.  It looks like it might stick out the same distance as the original turn knob, but it will leave a big, gaping hole in the side of the Gameboy because it's so skinny.  So that's a waste of time IMO.

thursdaycustoms
Offline
Cleveland, OH

Very thorough! Seems like a good quick fix. I actually like the idea of the wheels being harder to turn. My volume pots are almost always all the down since I prosound mine pre-pot.

But why not just buy a new volume or contrast wheel? They're pretty cheap. You can get tem right at Radio Shack. Or you can just drip a few drops of rubbing alcohol under the wheel, turn the wheel back and forth for about a minute and let it dry. Good as new after this.

Last edited by thursdaycustoms (Sep 17, 2013 7:12 am)

3ndymion
Offline
NYC
thursdaycustoms wrote:

Very thorough! Seems like a good quick fix. I actually like the idea of the wheels being harder to turn. My volume pots are almost always all the down since I prosound mine pre-pot.

But why not just buy a new volume or contrast wheel? They're pretty cheap. You can get tem right at Radio Shack. Or you can just drip a few drops of rubbing alcohol under the wheel, turn the wheel back and forth for about a minute and let it dry. Good as new after this.

I actually tried alcohol a few times before anything else.  It worked for a few minutes, but it was so bad that it returned to "broken" really quick.  Then, the alcohol wouldn't even work anymore, even after drowning it in alcohol.  As for the new wheel, I just got one, & it's way skinnier.  I choose not to bother with that cause I don't want a big hole in the side of my Gameboy.  : P