1. DooDooDooD

    OP DooDooDooD Newbie
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    I decided to make a post because I can't find much info on this, I accidentally chipped some of the volume wheel on my original GBA and now need a new one. Can I just replace the wheel or will I have to solder on a new volume potentiometer? If the latter is there a guide on how to do this? Thanks
     
  2. FAST6191

    FAST6191 Techromancer
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    The trick is usually less about replacing but finding the/compatible/improved parts to do the job.

    Similarly I don't know that anybody has ever talked about replacing just the wheel before -- most times anybody is messing with the volume it is because the pot has gone bad and they can't get in to clean it. Someone might have pondered a colour change at one point in time but that would be what most do.

    Do you have the option to get a backing material and flood fill with epoxy or anything like that?

    Looking at https://bitbuilt.net/forums/index.p...u-03_bottom_with_parts_pcb_scan_atv-jpg.1145/ from https://bitbuilt.net/forums/index.php?threads/gba-board-scans.807/ then the wheel attachment is peined over which instantly makes things more fun.

    Guide for soldering a new one? Buy replacement. Desolder old one. Solder in new one. It is still just about a through hole mounting so you have that going for you. Otherwise everything should be accessible to a suitably sized iron or hot air station for standard desoldering, you will probably want to fill in some solder with some glorious leaded solder rather than deal with the tiny dab or lead free nastiness that is likely there to start with. Some might go pump here, some might go solder wick -- play it as you will. Some people might get in there first with some side cutters and snip the pins (or destroy the whole pot) to just leave the pins to remove (less thermal mass and you can do one a time which prevents the others from cooling down and you maybe messing up a trace.. Do note you have some mechanical fixings at the board edge and it is not just the pins at the back. I am not really sure what to say otherwise -- it could be more basic with a single through hole resistor or something but not by much.
     
  3. DooDooDooD

    OP DooDooDooD Newbie
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    Thank you very much for this reply, I have already purchased a replacement volume potentiometer and as a beginner to soldering going through what you have written has helped a lot.

    The replacement part I brought is used for both the GBC and the GBA and some sellers say to use it in the GBA I will need to solder pin 2-3 and 4-5 while others make no comment of it. I cannot link an image because I am a new user but looking at the motherboard pictures you posted it doesn't look like the standard part needed to do this which added some confusion.
    With the replacement would I need to solder the pins together before or after it is attached to the board? I am worried about the solder melting from the pins as I attach it.

    Many thanks
     
  4. FAST6191

    FAST6191 Techromancer
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    You can break up a url a la https: // somesite .tld / blahblahblah or if you want to tell us the hosting site and the unique key for that picture if it is one of those then that works too.

    Without seeing what the replacement is or reading a description I can't say what needs to be done -- at this point I don't even know what the pins are being numbered as on the replacements (I can assume it is the same as on the mask* but best not to). Different pins or bridging things depending upon the application is not unheard of -- could be that you are soldering two POTs together to make one large one (or one half rated one) is the GBC and GBA vary in the resistance ranges they want (depending upon what goes it could even be a loudness mod if you are allowing more current to pass but I will skip that for now). Different sellers might also be selling different parts, hence the different descriptions.

    *looking at the full shots and then the sanded shots it seems two pins are not doing much of anything, and the mask skips numbering them accordingly. If the original was some Nintendo custom thing and the new one just happens to be the right size then it could be that the pins it uses are different and by bridging things you get the current going where it needs to go.

    Also looks like I messed up and was paying attention to the headphone port. The wheel is surface mount. Can still do all I said with the new solder, wick or pump, snipping pins and break pots though.
     
  5. DooDooDooD

    OP DooDooDooD Newbie
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    bit.ly /2PSZ5AZ This is a broken up link to the image I was referring to, I shortened the url as its very long however I can post the original if you don't want to use it
    Bit of a silly question also but does the position of the wheel matter when its being soldered on (for example if it's rotated half way until it can no longer turn will the volume when it's turned on be 50% as it should?)
    I very much appreciate these reply's, thanks a lot
     
  6. FAST6191

    FAST6191 Techromancer
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    2PSZ5AZ.jpeg

    Should not care wheel position it is soldered on with. Some things might take a reference depending upon where it is when it is powered on (ever had a controller where you held the stick if turning on and it ran that way? Quite possibly the same idea as many sticks also use variable resistors to tell where they are at) or when programming but for something like this not so much.

    Anyway looking at that image and the pictures of the board from the thread (also now https://gbatemp.net/threads/thinkin...fixes-compilation-thread.485501/#post-8628992 for forum searchers in the future)

    Quick image to show what is likely happening. Only the middle and outer pins do anything on the PCB (the others are just there). I am guessing here that the replacement uses the unused ones for some purpose that matches those there as soldered.
    GAME_BOY_ADVANCE_AGB-CPU-03_BOTTOM_STRIPPED_PCB_SCAN_ATV_with_volume_pots.jpg


    If you want you can figure it out easily enough if you have a multimeter once it arrives. Most likely as the GBA is a mono speaker device then it will reduce everything from both channels into mono for you ( https://components101.com/resistors/thumbwheel-potentiometer-5-terminal is not the same as the GBA but would make sense to bridge things to downmix to mono). If you wanted to get really fancy you could possibly have a stereo GBA if you can figure out somewhere to stick the second speaker but let's leave that for the time being. Alternatively it could be like I said earlier and the resistance needed happened to be double or half what the GBC needed and some enterprising type on aliexpress decided not to make two listings and instead tell people to solder stuff.
     
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