Adding a headphone jack to Mio C230! (and replacing/upgrading the battery)

[UPDATED the title 2/4/2008 to reflect additional topic that fits in well here – Battery replacement/upgrade, since the disassembly procedure is the same and you might do both at the same time]

Headphone Jack


Doug Wilson has submitted a fantastic article he put together that details each step of his upgrade project – installing a headphone jack to his Mio C230.   It is also a great way for many of us to be able to just peek inside without getting the screwdriver out.

I was hoping WordPress would allow me to import his submission, but it only imports the text, so for now Weblog readers, the next best thing – if you have Acrobat Reader (or another pdf display program) just click here to read his article exactly as he put it together.    ( the article is also available in Word Doc format here )

Thank you for sharing this Doug!

Battery Upgrade 

Craig Dean (CD) has submitted a great article he and his father put together  detailing each step of his upgrade project – installing a C220 battery into his Mio C230, resulting in almost 50% more output capacity!!


If you have Acrobat Reader (or another pdf display program) just click here to read his article exactly as he put it together.    ( the article is also available in Word Doc format  here. ) 

I find it interesting that the label on Doug’s battery stated the output capacity as  720 mAh, another gentleman stated that his was labelled 800 mAh, and CD’s is 850 mAh.    This variation would account for why some people are VERY disappointed in the battery performance!  The spare batteries for my iPaq looks to be the same dimensions yet the label states the capacity as 1500 mAh at the same 3.7 volts (too bad it doesn’t have the same wire and connector attached).

Thank you for sharing this Craig!

Is this a Mio mount; looks a lot different from mine?  Question posed by bleep55 on 4/26/2008 and I agree, it doesn’t look mine either.



  1. robbyg said

    Very nice work! A little too risky for me though since I don’t have very steady hands and would probably crack the screen or something!

    Just out of curiousity, where is the battery located in those pics? Does anyone know where I could get a higher capacity battery to replace the horrible one that comes with the unit?

  2. c230 said

    I believe the battery is black with the white label on it. Looks like there’s enough room to upgrade the battery too.

    This thread may be useful:

  3. robbyg said

    Very cool – thanks Dan for the link, looks like it should be pretty easy to replace the battery.. Now I just have to hurry up and decide if I’m gonna keep this unit or not… you’re making my decision much easier now!

  4. Dana Hartsock said

    A very nice hardware hack.

    I too find myself interested in replacing the stock battery with a higher capacity one. My understanding is the C220 shipped with a 1200mAhour battery. I’m guessing the C230’s 800mAhour battery was a concession to keeping the cost down a bit. Certainly putting at least a 1200mAhour battery would be desireable.

  5. c230 said

    I think we all agree Dana. We’ll probably all wait until the warranty period is done though. Personally, I like my Encore unit for the same money though – if there is no electricity around, it will transfer from it’s battery pack and actually charge the Mio back up, so that you don’t have to carry the two linked together all the time if the Mio battery had depleted itself. It will also charge your iPod at the same time since it has 2 USB ports.

  6. Doug Wilson said

    I did take a photo showing the battery clearly however I did not use this in the description. According to the label it is an S30 Rechargable Li-Ion Battery. 3.7V, 720mAh. BYD Company Limited, 338937010150. Made in China (what isn’t).
    I have dimensions if you need them however the only way that the battery can grow is in thickness. It is currently approx. 4 mm and there may be an additional 3-4 mm inside the case.
    Rgds, Doug

  7. robb1 said

    How is the battery connected to the electronics? Does it have some kind of connector that plugs into the PC board?

  8. Jim Rose said

    I use a “Pocket Power Bank” external USB power supply, it plugs into an AC socket to recharge, and I replaced the 4 AA rechargable batteries with 2600 mah AA’s; it can also be used as a battery charger. I think it cost less than $20. Use it for lots of stuff.

  9. Dana Hartsock said

    As long as there is room for greater thickness for the battery it is likely there will be a replacement that will fit. I guess the questions is, will a C220 battery work as a drop in replacement? They should be available and that it a 50% increase in capacity.


  10. robbyg said

    Here is one from Infinitybateries for the C220, but unfortunately they don’t list the dimensions. Doug – does the connector on this battery look like the same one on the C230?

  11. Doug Wilson said


    “does the connector on this battery look like the same one on the C230?”

    It is pretty difficult to tell from the photo but it looks the same. I would imagine that the connector itself would be the same between models.

  12. CD said

    Anyone know of a place to order the speaker connections? Based on Doug’s explanation, I figure if one could find a male and a female, you wouldn’t have to cut either wire… female from the board to the jack and jack to male (and the speaker.)

  13. Me.. said

    Hmm.. I’ve been thinking about doing this. But there’s one big problem, it’s MONO! 😦

  14. Jim Warters said

    There are a number of Li-ion batteries here:
    I have ordered from them in the past and have found them reputable. Most batteries have specs, including dimensions. For example, the 1,500 mAh battery ($11.95 plus shipping) is 3.5mm (thick) x 55mm (width) x 85mm ( length ) = (1/8″ x 2.1″ x 3-11/16″). Given all the caveats on Li-ion batteries (using & charging), I think I would prefer an external Ni-MH solution!

  15. Doug Wilson said

    I’ve been thinking about doing this. But there’s one big problem, it’s MONO!

    Yes, because the source is mono the output is mono. It is what it is….you get the same output to the left and right speakers. If you are listening to Yes, Close to the Edge or Pink Floyd, Dark Side of the Moon and you want to hear Alan Parsons incredible production value I think that you are using the wrong device.

  16. c230 said


    Let me ask a question that addresses questions others have asked me.

    Did you see solder pads for other switches on the board? People have stated that they wish there were external volume controls, ways to toggle screen off while playing audio, etc. TCPMP has a nice options screen for assigning many functions to hotkeys, but you need atleast one external switch first to serve as a hotkey.

    I’m not asking for myself, I think if I wanted all of these additional features, a higher-end model would be a better alternative.

  17. Jason Novak said

    Cool mod, I’ll have to do it. Would be nice if it could do stereo. I did something similar to this adding a jack into a factory GM car stereo using a $3 jack from radio shack …you can check out this post for more details on the part and it’s pin-out, I think everyone’s got to have a radio shack nearby.

  18. Doug Wilson said

    “Did you see solder pads for other switches on the board … external volume controls, ways to toggle screen off while playing audio?”

    I have uploaded the only picture of the board that is not included in the instructions.

    Your guess is as good as mine if any of these footprints are for a switch or volume control device. I think that you would either have to have a board layout and schematic or disect another unit that has the functions you want to include. I have neither.

  19. CD said

    Couldn’t you just put a line-level attenuator in line between the switch and the speaker?

  20. haco81 said

    I was thinking about this all the time!
    Jep, gonna do this too! But if I look at the pictures it is not necesary to remove the PCB and the LCD… just be carefull. 🙂

  21. c230 said

    I suppose you could; I was thinking more along the lines of an assignable hot key that could serve different purposes depending on what program you were running. The larger solder pads by the antenna connector look like a potential area? Anyways, that is a great photo to look at – you can even read the battery label.

  22. BenNoach said

    I did this mod. Works great. Blew my ears off.

    I left the board in and drilled by hand using a bit. It was easy and I had good control.

    I’m using a small fm transmitter to broadcast the sound over my car audio.
    It is mono but I can hear it much better.

    BTW on the player you can join the audio for mono out and not lose the channel.

    Thanks for the pictures, I would probably not tried it without your good documentation.

  23. benblue said

    I’m very interested in the potential battery upgrade. If someone tries the C220 battery linked above, or has one and can provide measurements of it, that would be very welcome info.

  24. strider_mt2k said

    Excellent info here.

    I just picked up (and subsequently opened up) a Mio c230 and it looks like that is a pretty straightforward mod.
    Thank you for sharing the info and great pics online!

  25. Mike said

    Doug Wilson,
    I looked at the way you have this set up. The jack you used is a stereo jack.
    It acts as a double switch. If you are going for mono sound you should attach the two black wires to the solder post you bent down and ditch the second feed (ring feed) for stereo headsets. that way if someone did put in a stereo headset they would get sound(in one ear, but sound)and you can use your mono headset.
    Since I have a stereo headset and not a mono I thought I might be able to shed some light on this for those wanting to use your stereo headsets.

    If I am wrong please correct me. (you better be absolutely sure if you want to correct me.)

    Use the solder terminal you bent down for the black feed from both the speaker and the board. feed both moving parts of the switch from the board’s red wire. feed the speaker red wire with one of the remaining solder terminals. This will let you use a stereo headset and get sound in both ears.


    disclaimer: do this at your own risk I accept no responsibility for your foolishness.

  26. Mike said

    Also Great job on the pictures they were extremely helpful to me when I did this so I didn’t accidentally drill in the wrong place. Excellent. Thanks.

  27. CD said

    I want to hook a wire from the headphone jack to the input on my car radio. What goes where if I want the same sound to come out of both channels?

  28. Mike said

    if you have the same head phone jack as in the pictures, then I would wire it my way so everything is properly grounded and fed.

  29. Mike said

    I posted a diagram at

  30. c230 said


    I agree, if you’re using an iPod type cable (3.5mm stereo mini plugs on both ends) I would use Mike’s instructions for the headphone jack wiring.

  31. CD said

    That is awesome, thanks! That’s the exact part I bought at RS. I want to be able to listen to mp3s out of headphones, too, even if it is a mono sound.

  32. Doug Wilson said

    Hi Mike:

    I believe (was told by the electronics supply store guy) that this is a mono jack. I use i-pod headphones (i.e. stereo) and all works extremely well. I have tried changing the channels setting in media player from stereo to mono (same sound in both channels) and don’t really hear much difference. I get sound in both ears of the headphones and on all speakers of the car stereo. I’m not sure what the deal is but it works. I have never tried “mono headphones” since I would think that you would just use standard ear buds or headphones and not a single earphone (do they still make these?)

    “disclaimer: do this at your own risk I accept no responsibility for your foolishness.”

    A wise man can learn more from a fool than a fool from a wise man
    Regards, Doug

  33. c230 said

    Doug + Mike,

    Either method is fine. I was supporting Mike’s wiring diagram and explanation for his stereo jack configuration. Stereo headphones have always been backwards compatible, so of course if you use a mono jack, then Doug’s description is correct as well for the mono jack configuration, and as he stated, this will work fine as the jack should mate with both the left and right channel contact surfaces of the cord plug if you insert until it falls into the detent. Sometimes, if you insert just shy of the detent or just past the detent, then you will only supply one of the channels, rather than both left and right.


  34. Mike said

    “A wise man can learn more from a fool than a fool from a wise man
    Regards, Doug”
    -I agree, I still don’t want to take responsibility for people voiding their warranty… 😉

    The jack I listed on my website is a stereo jack. Our feed is mono so we will never have true stereo but it can be balanced mono.

    For the curious:
    The reason it works either way with the head phones is because the head phones are connected at the ground wire. Doug’s way of wiring runs the two speakers in-line and skips the ground. It works because it still has to go through both speakers to ground out and the speakers do not demand a specific positive or negative. If there was a diode in-line (almost never done) on the wrong side of his setup, it would not work.
    The way I suggested runs the stereo head phones in parallel, both get fed from their respective source wires and the ground wire is used. I guess it really doesn’t make much difference if you are just using headphones…. (although you will know which speaker is out with parallel instead of both speakers being out at the same time if one goes in-line.)
    Either way both of the two front prongs must be used to get a stereo headset to work.
    ANYWAY…. Have Fun with your new headphone jack. 🙂

  35. Mike said

    also now that i think about it my way would prevent a mono plug from being used while Doug’s would let you use either mono or stereo headphones.

  36. strider_mt2k said

    Good info on here folks!

    I like the idea a lot and I think I’m gonna go for it, but I think I’m going to look for a way to wire in some kind of attenuator for the earphone output.

    Having a speaker level output is cool for directly driving speakers, but it can really blast into a line level input unless you are very careful to set levels prior to plugging it in.

    I also had concerns about balanced mono output, but you’ve handled those already from what I’ve read.

  37. c230 said

    Or you could set your default volume in autopatcher and MioMap lower, and then turn it up manually as needed.

  38. strider_mt2k said

    I didn’t even know that was possible! 😀 How cool is that?
    That is a good “best of both worlds” option if you want to avoid the extra hardware modding.

    I come from a hardware background so that’s how I approached it.
    II might actually see if I can position a 1K trimmer in there for the adjustability factor.

    The advantage there is that you can leave the audio maxed out for using the speaker but still have the line out capped at the max level you set.

    With any luck at all I can set up an additional hole to access the trimmer, but we’ll see. 🙂

  39. strider_mt2k said

    BTW, next coffee is on me.

    Thanks for your work!

  40. c230 said

    I thank you again strider. FYI, when using TCPMP, you are also able to control the preamp volume as well.

  41. strider_mt2k said

    As far as power solutions go, we seem to have it fairly easy, as most power accessories designed for the Motorola Razr that I have tried function quite well.

    iGo (maker of charging and power accessories) makes a portable charger for about 20 dollars that uses a couple of AA batteries, as do others.
    I work for Radio Shack, and we recently got a Lenmar branded external battery that is very nice too as it has a USB port and offers higher capacity and a more standard USB port, however it is a bit more expensive at around 40 dollars.

    For me it’s either pursue a solution like this or build my own Minty Boost.!—Small-battery-powered-USB-charger/

  42. CD said

    Anyone have a link to the iGo battery powered recharger?

  43. strider_mt2k said

    It’s 5 Dollars more at Radio Shack, but includes the first tip free.
    (That would be iGo tip# A35 A32)

    The Lenmar Battery at and in stores is catalog number 23-464

  44. CD said


  45. Endicott said

    A less expensive power solution is shown at
    $3.95 (plus shipping). Battery holder: AA x 4 with USB interface connector, power switch and belt clip. Uses 4xAA NiMH or Ni Cad (not alkaline which have a higher voltage) to provide power into a standard USB connector.

  46. c230 said

    Nice find! At that price, you could have a few on hand for a long hike for instance, and since they use rechargeable batteries, when you get back, charge them all up again for the next occassion.

    Do you recharge the battery packs via the same USB port?

  47. Endicott said

    According to the company’s site, the battery holder has a switch for “power out,” “power in” & “off” and they comment on using the holder to recharge as well. I’ve ordered a couple to see how they work. Shipping on 2 holders plus a “CH-P1000 Smart Charger+12 AA 2600mAh Powerizer NiMH Cells with Car-plug” was $8.98 UPS Ground from CA to NJ.

  48. strider_mt2k said

    Oh I like that one better! Very nice!

    Oh that iGo tip is A32, sorry.

    [Edited by c230. Fixed the typo in the comment above to avoid any further confusion with the tip recommended on the website. I appreciate your sharing the info strider.]

  49. legger said

    When you hook up a headphone cable to the jack does it kill the sound to the internal speaker?

  50. strider_mt2k said

    No problem!
    And the correction is much appreciated!

    Endicott’s blew mine away though. I’m ordering a couple of these things for myself right away.

    It kills me that my bargain-priced GPS is giving me BETTER bang for the buck than handhelds I’ve owned only a few years ago that cost 4 times as much.

    The only diff is productivity apps that I never used any way and battery life.

  51. c230 said

    Since we haven’t started a seperate thread for battery replacement yet, I’m throwing a great link in here on replacing / upgrading the battery.

    Even though the instructions are for a Mio 310, by using Doug’s disassembly instructions instead, the 1250 mAh battery that is mentioned (with sources) in the thread sounds like the perfect upgrade candidate. Perhaps someone will get gmaniac to provide the dimensions to insure that it will fit.

    (Or did Dana already upgrade hers? 🙂 )

  52. HaCo said

    I added an audio connector this evening. Wow, that was quite ‘exciting’ *uhum* stressfull. I didn’t remove the PCB to place the connector, but if you do so too, be VERY carefull. I touched the microswitch twice with the drill, that is not so good, but fortunatly it survived. The connector was placed a bit too high, so I had to cut a litle bit away from the cover, but at the end everything is just ok.

    Tested it on the my car (have an aux stereo jack) and works perfect, of course in mono, but fortunatly left and right play the mono (thanks to the way the connector is wired).

    Thanks a lot for this tutorial!!! AWESOME!

  53. strider_mt2k said

    I just finished cleaning up from my headphone jack installation.

    Everything went perfectly thanks to the tutorial!
    I elected to drill the hole by hand using three increasingly-sized drill bits to avoid taking the whole thing apart, and it all works as-advertised with clean monaural sound coming through both headphone channels.

    I opted out of installing the headphone level attenuator because of the wiring complications it brings. (Easy enough to turn the volume down!) 😀


  54. strider_mt2k said

    @legger: Sorry! I completely missed your question earlier, but since I just finished doing this…

    Yes, if you use Radio Shack Cat#274-246 1/8-inch Stereo Phone Jack or equivalent and connect the wiring the same way as the tutorial shows it does indeed cut out the speaker when you plug into the jack and it comes through on both channels. (in mono, but over both channels)

  55. strider_mt2k said

    I’ve ordered a C220 battery for my C230.
    As always, I’ll let you know if it works when it arrives.

  56. c230 said

    Note that I’ve…

    [UPDATED the title 2/4/2008 to reflect additional topic that fits in well here – Battery replacement/upgrade, since the disassembly procedure is the same]

    I’ll await some photos from one of you to post in the addendum.

  57. CD said


    I sent you a write up of the battery swap.

  58. strider_mt2k said

    That pic looks good CD!
    I’ll have to review the document once the link works 🙂

    Very cool to see what I’m getting into in advance, although the headphone jack mod gave me a decent lay of the land.

    It’ll probably be a week or so before I see mine arrive.

  59. CD said

    This info was compiled by my father, as he has both the c220 and c230. He is currently working on some runtime stats, which I will post when he is finished.

  60. strider_mt2k said

    Link works now.
    Great stuff man!
    I can hardly wait to do mine now! 😀

    Do you knock out the headphone jack mod while you were in there too?

  61. c230 said

    I find it interesting that the label on Doug’s battery stated the output capacity as 720 mAh, and CD’s is 850 mAh. This variation would account for why some people are VERY disappointed in the battery performance! The battery in my iPaq looks to be the same dimensions yet the label states the capacity as 1500 mAh (too bad it doesn’t have the same connector attached).

  62. A Guy said

    Wow, my untouched C230 battery is a 1230 mAh at 3.7V. I just opened mine up and was surprised to see I had a better battery in it from the factory. Maybe Mio upgraded the battery after some customer feedback? If it helps, I bought mine Nov. 07.

  63. c230 said

    Kind of sounding like Mio is installing whatever batteries they can get their hands on and who would complain, unless, like Doug you found a 720 mAh battery inside.

    Got me curious now 😉

  64. strider_mt2k said

    c230 I’m getting ready to open mine up again out of sheer curiosity!
    I didn’t note it when I had it open originally.

    I know my C220 battery shipped, but it’s still going to be at least a few days until it arrives if not more.

  65. c230 said

    I know I’m getting carried away with this one, but if anyone comes up with a nice tube to add that would serve as a stylus holder, I think that would be a great mod too. The tube would guide the stylus and insure that nothing would get damaged (vs. just adding a hole in the case)

    Radio Shack doesn’t have a kit for this, do they?

  66. strider_mt2k said

    Unfortunately not. 😦
    Of course it doesn’t help that we’re busy filling up all the internal space with upgrades, does it? 😀

    While an on board solution would be handy, based on my experience with past handhelds I would still say a good multifunction pen/pencil/stylus combo is the best bet on that one for comfort/utility.

    Still, some creative person might come up with something. Who knows?

  67. c230 said

    Just to clarify the “official” battery capacity specs, Mio Europe lists it at 750 mAh ( 2 hours) and Mio USA lists it at 800 mAh (2.5 hours).

  68. strider_mt2k said

    I noticed that a Nintendo DS Lite stylus fits very nicely in the clip just behind your C230 on it’s suction cup mount. That might be handy in a vehicle?

  69. c230 said

    I’ll bet Mio never envisioned anyone using a stylus with their C230 model!

    Thanks for all of your recent comments Strider. Your in-vehicle suggestion will come in handy, as I just throw my stylus in the case with the C230 when it’s not in my vehicle.

  70. strider_mt2k said

    This kind of tinkering is right up my alley and your site appears to be spot on with the developments for my GPS and the most active on the subject!
    I think it might have had something to do with me buying my C230, as I researched it when it went on sale and we had a trip coming up.

    I’m just a hardware hacker/enthusiast with an electronics background who is chatty. If something good comes of it all the better! 😉

    It’s a great site!

  71. Davvinchi said

    My C230 has a 1230 mAh at 3.7V battery as well. I guess I won’t need to upgrade this time. I don’t know how long it lasts off the charger though. Mine was bought in Dec ’07 as my Christmas present.
    c230, I agreee with the stylus holder idea…if I were to do it I would want to be able to have it hold the stylus and not loose it (have some way of keeping it in place) and I would want to have it incorporated into the flow of the mio’s design, in other words I would make it a hole with an attached tube inside the mio.
    However, I normally use a retractable pen, and when closed and it makes a decent stylus. I’ll ask my art class to come up with an idea for you. 🙂

  72. strider_mt2k said

    I was looking at the Nintendo DS Lite stylus I have as a likely candidate.
    I have other stili, and I know there are smaller ones out there, but this one is readily available at department stores and probably the smallest that’s realistically usable.

    It looks like there might barely be enough room between the battery and one side.
    It would insert right next to the power button at the top, but is too long to fit completely inside. Probably the top 3/16 to 1/4 inch of the stylus would stick out.

    IF it fits it’ll be pretty tight, maybe tight enough to stay captured.

    Ideally some sort of a tube or protective sheath should be in there to protect the C230’s innards from wear and dust associated with the stylus being inserted and replaced repeatedly. Like a drinking straw perhaps.

    The other worry I have would be accurate and clean drilling of that hole!

    I haven’t cracked mine open again yet for fear of courting fate with the various plastic tabs and such.
    I’ll wait until my C220 battery arrives and use that opportunity to check out the clearances inside.

    Interesting idea! It makes me wonder how far the hardware mods can go.

  73. strider_mt2k said

    Just received my 4 “AA” battery holder/USB pack and I have to say that it’s of higher quality than I was expecting!
    This’ll be a handy one for keeping our MP3 players charged up as well.
    If anyone was waiting to see if they should I’d say go right ahead.

    Thanks again to Endicott, who posted the link!

  74. strider_mt2k said

    The C220 battery arrived this morning and was installed in minutes, no problem.
    My original battery was a 750 720 mAh one for anyone keeping track.
    I went ahead and re-used the existing mounting tape because it was in great shape when it came apart.

    On the stylus, I gotta say I don’t think it’s worth the trouble to build it in, although there is a little room there for one.
    If someone wants to try and build one in, good luck!

    Yet again I have to thank you folks for all the hard work you’ve put into bringing us all the info for these mods.

  75. Wildpig said

    Is it true that C220 has a stereo headphone jack? Wondering if mio is compromising stereo sound output on c230 just to save a few bucks if that’s even possible. Anyone got a real close look at the circuit board to see if there’s an extra connection on the board that might produce stereo sound? If that’s the case, I am definitely adding the headphone jack and probably even also upgrading the battery. 😉

  76. c230 said

    Someone would have to compare the circuit boards to see if the solder pads are present for a stereo jack. If they are present, this end result would be better, but anytime you’re soldering an assembled circuit board, you take on far more risk than you do just splicing into the speaker wires.

  77. Wildpig said

    True, but I am so that hasnt deter someone before ;). If that is possible, the c230 would be like one of the best bargain multimedia/GPS deal there is.

    I currently have a cowon q5w with GPS cradle, but i would still modify my c230. The only reason i haven’t is that i am hoping that someone knowing electronics better than me (perhaps a mio insider? 😉 ) can find that extra connection. I hate to have to open the case twice. All the parts are here and ready to go though

  78. strider_mt2k said

    Hmm. Interesting stuff.

    A guy I work with has a C220.
    I wonder how he’d feel about some exploratory surgery if I opened mine up alongside his? We’ll see.

    It could shed some light on things one way or the other on how truly similar or dissimilar the C220 and C230 models are.

    I’m a little jealous of that stereo jack too, although at this point I shouldn’t complain as the headphone jack and battery upgrades on mine both went extremely well.

  79. Wildpig said

    that would be real nice if your friend let you do that. i have all the parts ready to go. but i haven’t started because i don’t want to do two operations. i feel almost certain that there should be a stereo output on there.

    if we can get stereo on this, this would be a bargain mediaplayer/gps, unbeatable deal.

  80. strider_mt2k said

    I just got off the phone with him and he’d rather not.
    Understandable of course.

    Don’t give up hope though.
    We still have a bunch of clearance C220s that will only drop over time.
    If it gets to less than 100 bucks I’ll buy one for myself.
    I understand a guy’s been successful dropping a full CE install onto a C220, but I’m unaware as to the legalities of this based on my own research.

  81. Doug Wilson said

    There is a position on the board which looks like it might be meant for a factory headphone jack. This turns out to be directly below the antenna connector whch makes sense as both of theese items would need to protrude through the units housing. Maybe some hardware guys can recognize the footprint as it is smaller that the jack which I installed.
    A friend of mine recently purchased a C230 specifically due to the fact that he can make these mods. I will ask him to have a look as well.
    Detailed pictures are in the following location.

  82. c230 said


    Thanks for the excellent photos Doug! Sure looks like you are correct (and the output is probably stereo too). And the 10 pads underneath the headphone jack pads – are those for hot keys for the Gamers, in case a variant model is produced without a touch screen? Or is something hanging there on the backside?

  83. Wildpig said

    Awesome, y’all the best!!! ;). I just wish i know more about electronic than just enough to follow direction for soldering….

    Anyone can confirm the stereo out? I am sure this won’t take long.

    hmm the 10 extra pads, the plot thickens…..

    Any Mio engineer out there we bribe? 😉

  84. Wildpig said

    Doug, btw, i see you haven’t upgraded your battery 😉

  85. Doug Wilson said

    No, battery upgrade is soon though. As you see I really got burned on my battery power 😦

  86. strider_mt2k said

    Ahhh right where our headphone jacks got modded in.
    Thanks for the pics!

    Well maybe it’s just a matter of some wiring, but there is an open spot for an IC chip there too. That makes me wonder if it might be associated somehow.

    It doesn’t make much sense to me though.
    The mono audio system has an amplifier that is driving the speaker loudly and clearly, so there is obviously an audio subsystem of SOME type in there.
    The only reason to use one chipset over another would be cost, as you still have to solder them in anyway.
    That being the case, don’t you think the speaker would plug in a little closer to that area as opposed to out near the center of the board?

    There’s only one solution: Find an engineer at Mio and get them drunk.

  87. Doug Wilson said

    I ran across a US government website about six months ago when I was looking for information on a 2wire router which I have. The site had detailed photos of the PC board and supposedly all electronic devices which are imported into the USA have the same information availlable. If this is true then detailed 230 information should also be available. I did some digging but could not find this information again.
    Perhaps somone out there with good internet sleuthing skills and some time on their hands could locate this.

  88. Wildpig said

    looks like we are getting warmer 😉 I can feel it… Oh well, i guess you will have to remove your headphone plug for a new mod? 😉

  89. Doug Wilson said

    I don’t know if it will help any but I found the thread regarding my router problem. This discusses searching the FCC website for product information. If anybody feels so inclined they can do some investigative research and see if the Mio information is there.

  90. strider_mt2k said

    @Wildpig: Maybe just to make those connections, but you’d still need a headphone jack after all.

    Heck, I’m not above taking a small speaker or a set of scrap ‘phones and just trying various combinations of contacts to see if anything happens.
    Monday is a day off for me so maybe I’ll do a little poking around inside of mine now that I’m not worried about disassembling the stupid thing.
    (No fair you guys having all the fun.)
    EVEN MORE SO THAN SOFTWARE playing with your C230 at the hardware level can damage or destroy it…or you.
    I’m experienced, so if I blow mine up I know EXACTLY where to kick myself.

  91. strider_mt2k said

    Sorry folks, no luck here.

    I did some real basic tests with a tiny speaker I have here and a multimeter and I don’t hear anything, nor do I see any anything in the way of voltages at those pads when trying various combinations of them.

    It’s gonna take more knowledge and better equipment than I have at any rate.

  92. strider_mt2k said

    After looking around online I see that Mio has a model C238 for sale overseas.
    (I like it’s color scheme.)
    It seems to feature some traffic monitoring and input option stuff that might account for the space and missing components on our circuit boards.

    I only found out after doing a search for cases and seeing a couple listed as being for the C230/C238.

    While having stereo would be very cool, I’m kinda happy with mine as-is at this point and won’t be pursuing this line of mods much further unless there’s a breakthrough or something.
    Not having stereo keeps me from putting music on my SD card, but since the speaker is so clear I DO put music VIDEOS on there in addition to TV shows and movies.

    (I found lots stuff on You Tube using the Fast Video Download add-on to Firefox.
    Miles Davis, John Coltrane and the like as well as more modern stuff.
    TCMP handles .flv files like a champ and dithering helps quite a bit!)

  93. strider_mt2k said

    Sure I won’t be pursuing it… 😉

    I slogged through a couple of translated web sites and found this bog with some excellent pics of the Mio C238, including a side shot that shows a larger rubber cover for guess what? That’s right, the antenna connector AND A HEADPHONE JACK! (Notice the off-center placement just like our mods have!!)
    (You’ll have to scroll down a bit for the pics.)

    I haven’t been too good with forwarding the hardware or software mods, but hopefully my piddlin’ bit of research has helped a little. 🙂

    I wonder if the C238 will ever become available in the US?

  94. strider_mt2k said

    I hate to react so quickly again, but THAT’S NO HEADPHONE JACK!
    It appears to be a secondary antenna port for the traffic monitoring feature!
    (My fault for not reading through.)

    Okay well that lays it to rest then, doesn’t it?
    I don’t think the C230 was designed with a stereo audio system to reduce it’s cost to manufacture.

    (Sorry C230)
    (Sorry all)

  95. c230 said

    That was a great find! As you said, the inquisitive among us can quit pokin’ around now. 🙂 TMC has traditionally been via an external device, so the primary reason Mio probably omitted the headphone jack was to make room for the TMC module and jack on the higher-end variants.

    Thanx so much for sharing!

  96. strider_mt2k said

    Hehe, even learning why you CAN’T do something is still learning, right?


  97. Wildpig said

    heh, that’s ok, i am sure there will always be someone who will be crazy enough to add their own stereo circuit 😉

    (wishful thinking ;( )

    Anyway, if anyone also have a mio c220, maybe they can do a comparison?

  98. strider_mt2k said

    Side note:
    If you are looking for a case for your headphone jack-modified C230, make sure it’s a case for the C230/C238 and it will accommodate your headphone jack without the need for modding your case too!

  99. Andrew said

    Can someone with a C220 battery installed in their C230 verify both that it fits properly and perhaps a real-world battery test (ie time from full to empty)? I know I should see nearly 50% improvement over my 850mAh (I opened mine up to check), but I am wondering if there is truly a strong case to replace a nearly new battery in my C230.

    Thank you!

  100. Andrew said

    On my 850mAh battery, I got a battery life of 2 hours 20 minutes. The 1250mAh battery should theoretically have a 47% better lifespan, thus giving it around 3 hours 25 minutes. Can anyone confirm or deny this extrapolation?

  101. Wildpig said

    so i saw in another thread on here that Eu ver of mio c230 has the headphone jack. is that true?

  102. c230 said

    I think the conclusion was that some sellers stated this in error (probably based on C220 data when initially released), just as some sellers in the US stated that the map data was still on the SD card.

  103. strider_mt2k said

    Just got a decent little leather case on ebay.

    Note that not only does it accommodate the GPS mount and two memory cards, but it’s also made for the C238 so it leaves room for a headphone jack if you have one modded in.
    (Perfect fit on mine!)

    An added bonus is the small metal ring attached with a sturdy loop on one side.
    I’ve already tried it and you can fit a Nintendo DS Lite stylus in that loop to keep it handy!

  104. AdamK said

    This might be a naive thought, so please correct me if I am way off. If this device runs a Windows-based OS and has USB capability, then would it be possible to mod a USB audio driver dongle to plug into the mini-USB port and act as the audio DAC?

  105. c230 said

    I sure wish I was able to search within the comments, and not just the titles (Many of you do too, I imagine) as I have already researched this and entered the results somewhere. Adam, I’ve had the same thoughts and came to realize that the USB port isn’t capable. I can’t recall the exact terminology at the moment, but I think it’s along the lines of device port vs a host port.

    It may have been you asking on GPSpassion yesterday, and had the WordPress search worked, I could have responded then, but in the end, NO I don’t bekieve that is an option.

  106. AdamK said

    Oh well. Thanks for the heads up, c230! That would make sense regarding the port assignment. I did pose the same question yesterday on the gps passion forum. In any case, I may attempt the hardware mod if I get antsy enough for a little project. 🙂 I have an old junk PC sound card sitting on my desk, and I’m wondering if I could arrive at a similar result if I pulled the mini audio jack off that board and used that. What do you think? Maybe that wouldn’t work if it doesn’t mute the built-in speaker upon plugging in the cable?

  107. AdamK said

    Come to think of it, maybe the kind off an old boombox would be better since it would have the circuitry to mute the internal speakers when you plug in headphones…

  108. c230 said

    Yes, in my opinion, one that’s as similiar to the one pictured would be the best way to go, if you are going to do the mod. And by following the guide, you are least prone to damaging anything.

  109. benblue said

    Regarding the battery issue, here’s an inexpensive alternative that provides much longer operation away from a power source:

    I have one and am using this to connect it to the Mio.

    Works well so far. I haven’t empirically tested total run time yet, but based on calculations with 4 2000mAh batteries it should provide nearly 10x the time of the stock internal battery alone.

  110. TCZ said

    Well there you go, that leather case solves the need for storage area for our Stylus 😉

    Now about that Stereo out, im not ready to give up yet, Im planning on finding out which chip in the c230 takes care of the sound and dig in the spec sheets to see if there are pins for the stereo channel were missing.

  111. TCZ said

    OK, the sound chip is on the other side of the PCB its a Woflson microelectronics WM8976 low power codec

    It IS a stereo chip.

    The diagram and specsheet is available here

    Also, on the reverse side of the PCB there are 4 groups of solder points on the edge of the pcb. Im guessing these are for hardware buttons.

    Time to start hacking.

  112. TCZ said

    Allright, here are the pics.

    The back of the PCB

    A Closeup of the Audio chip

    btw i was reading the spec sheet of the audio chip, theres a lot of interesting features in there, microphone in, aux in and out, etc…

  113. Wildpig said

    TCZ, very nice 😉

    It’s nice to be able to confirm this. I find it hard that anyone nowaday would make a non stereo decode chip as you can’t really save much money on that anyway. It’s much more likely that mio use a stereo chip but just didn’t wire it as stereo because they didn’t need to in the c230.

    Please keep us posted on this. I still got my soldering iron and the plug i bought from radioshack…

    I almost totally gave up.. I bought a c320 on ebay the other day for about $120 (the $120 dollar solution to the stereo output problem, heh ;)). Was about to put up my c230. good thing i didn’t yet….

  114. ToniJ1960 said

    On the stereo audio I would use a high impedance input signal tracer,maybe made from an old radio just tap into ther volume control 🙂 ,to check for audio signals on th extra pads.Or check the circuit with the chip info that was given here and trace with the signal tracer to their ends.

    For a volume control if you add an output jack why not use a cord from a headphone that has an inline attenutor and just add a second plug at the other end rather than the phones so its got a plug at both ends and attenuator in the middle.Should be easy to grab hold of at any timer and change 🙂

  115. c230 said


    I finally figured I would upgrade my battery this morning, since I had my new battery and Craig’s instructions up and ready. I pop the rubber covers off, take the two screws out, snap the cover off carefully and read the battery label.

    1230 mAh, and my new one appears to be smaller, but it states that it is 1250 mAh. I guess I was one of the lucky ones. Well, I figured I’ll just leave it be for now, because I can’t imagine that the new battery will be much different in my case.

    Great set of instructions though!!

  116. Andrew said

    Yeah, I managed to upgrade my battery recently – was not so lucky originally as I was given a 850mah battery = 2.33 hour.

    Bought the battery for $14 shipped

    Installation was a relative breeze – tho i preferred taping the battery back onto the board rather than on the cover because of the wire length.

    New 1250mah gets me 3.5 hours, so my original guesstimate proves to be correct – Extra hour or so of charge! Woohoo!

  117. MioZ said

    Any progress on that stereo headphone jack? This is the final piece that will put this little device over the top. Of course the battery upgrade will be in order once I open it up. My Canadian C230s has a pathetically weak battery, 750 mah IIRC. It’s always charging it seems.
    You’ve done some fantastic work here both on your own and at compiling other info from other mio wizards everywhere. I’ve only had my device for about a month and it’s been a lot of fun! Kudos to you. I’ll be contributing to your coffee fund!

  118. c230 said


    Thank you for your support! My guess is that the stereo jack will be a little over the top for most.


    If I forgot to thank you for the battery source recommendation, I’m doing so now. I guess it’ll just be a spare for now though.

  119. Bleep55 said

    Does anyone have any information on the mount pictured in the C230/C230 flip case item description that has been posted on Ebay. In a couple of pictures it shows the Mio in the case attached to the mount. Did the Mio C230 ever come with this mount? Is this an aftermarket mount? Any info would be appreciated. Thanks

    [edited by ameridan to help bleep out]

  120. c230 said


    I added the photo you are referring to above (at the bottom of the blog). I agree, it looks a lot different from my mount. Betcha it’s a EU C230 mount.

  121. Wildpig said

    I still have my c230 and the headphone jack ;)…… Ready to go whenever….

  122. Mark said

    Anyone come up with the stereo wiring yet?
    Dying for this little hack!
    Also, anyone know if there’s any other voices then the built in?

  123. c230 said


    There are other voices, but only about three others that work with TTS and they really aren’t significantly better than Samantha in my opinion. I personally wouldn’t count on seeing a doable stereo jack mod for the C230 either, but I’ve been proven wrong [once 🙂 ] before.

  124. Josh said


    In Holland i just bought me a Medion 96840 (E3212). It has a 3 1/2 inch display, Samsung 400 MHz-processor and is based on Windows CE 5.0.

    I also want to use this GPS for hiking, for this I need a better battery then the one supplied with this Medion.

    I opened up the case and discovered that this device has the same battery as the one on MIO C230: S30 Rechargable Li-Ion Battery. 3.7V, 720mAh. BYD Company Limited.

    What I would like to know is what the best battery would be to replace this S30 with? Offcourse i’d like this to be a battery with a very long lifetime.

  125. c230 said


    The new battery I bought on eBay is actually smaller than my original, but it states that it is 1250 mAh. and it turns out my C230 battery was 1230 mAh. I guess I was one of the lucky ones. Well, I figured I’ll just leave it be for now, because I can’t imagine that the new battery will be much different in my case. It is still sealed in the package, and I’m sure it would work for you, so if you have a hard time ordering it from China, I’ll gladly sell mine to you for what I paid + shipping. SOLD

    I don’t think you’ll find a higher capacity battery that has the correct connector and will fit in your unit.


  126. Wild Bill said

    Thanks for your detailed article on upgrading the battery. The swap of my OEM 850 was quite easy.

  127. Mark said

    any news on the stereo headphone jack wiriing and instructions?

    Thank you!

  128. Sorry Mark, this unit just wasn’t designed for it.
    The mod as it stands work well, however.

  129. Jaan said

    I don’t know how to get in contact with C230/Ameridan directly, but I found a good source for cheep external USB battery packs. A guy at the MIT flea market last Sunday who I’ve known for years had a bunch of iPod Shuffle “iRecharge” batteries for sale. $5 for 1, $4 for multiple. It’s this exact one…

    I bought 1 for myself and it was able to recharge my C230 fully once, and up to about 20% again on the same charge. I’ll have to take my unit apart and find out how big the battery is, although battery life in mine is no problem (I bought it almost exactly a year ago).

    I talked to him about shipping, figuring people here would be interested, and he said he’d ship for $4.50.

    The guy is Stuart Cody and he runs a little custom battery shop in Boston (he made the batteries that powered the IMAX Everest film). Full disclosure; I used to work for this guys years ago.

    His site is; and his contact info is there.

  130. c230 said


    Thanx for sharing. I’m happy to post the info for anyone interested. My current usage is primarily in my vehicle(s) so I’m not in need of external power packs at this time, but you never know when it might prove useful.

  131. Chris Meyers said

    anyway to run this without a battery in place? my battery is shot 45 secs of life without a cable, and i want to just remove the battery as it gets extremely hot whlist plugged in.the problem i see is there are 3 wires going to the board from the battery 1 red 1 black, 1 white. if i twist the red and black together, will the unit still work?when i unplug the battery the unit shuts off.

  132. Mark said


    Looking at the diagram, it strikes me that pins 29 and 30 on the chip give out headphone right and left.
    Pins 15 and 24 should handle grounding and sensing.

    Any reason this wouldn’t work?

  133. c230 said


    You may well be correct (output in stereo), but not knowing whether the input is hooked up for stereo, I don’t know what the outcome would be. Most of the readers that did the mod were looking for an easy method, which means keeping away from the circuit board with the soldering iron.

    Let us know if you have luck, and I’ll be happy to post any article you publish that takes the audio mod to the next level.


  134. James V said

    Thanks to Doug for the nice documentation. My C230’s speaker stopped working this week. My wife gave it to me for Christmas last year, so the warranty is up. I opened up the device and reseated the speaker cable. Now the audio works again! I’m happy and my wife will be too.

    Great blog, Dan. I’ll bookmark you for future reference.


  135. Robert said

    Thanks for pointing out that headphone install guide. I applied the same principles for my Garmin Nuvi 255W and it worked like a charm. Samantha is now whispering through the headphones, but only when I tell her to 🙂

    There were some particular challenges with the fact that the unit is considerably thinner than the c230. I put the socket between the battery and the screen, flattened the connectors, and it’s just great.

    Thanks again,

  136. Adam Ward said

    I just did it! Thanks so much. I got a 1250mAh for $13 including shipping.

    My only advice would be to be very careful when removing battery. The sticky tape is really a pain. While prying mine up, I noticed that their was a thin dark gray plastic wrap around the batter and I simply ran a razor blade on both ends to cut the wrap, then pulling up the wrap was very simply. I would not advise heat at all.

    Good Luck! …and again thank you for helping us “braver” folk who simply want more from the electronics we depend on.

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