TomTom One v2 earphone modification

TomTom One v2 with earphone modificationTomTom decided to remove the earphone plug from their newer version One. This blog entry will describe how you can add your own.

Why would TomTom remove the earphone plug? There are a few simple reasons, one being that the new version has a slimmer formfactor with less room for plugs, and the other being that they probably don’t want it to compete too much with the XL and Rider versions.

When my iPaq PDA died on me a few weeks ago, I was in desperate need of a new navigation system, and it already was clear that it had to be a TomTom, because I like the simple user interface and the clean look of the map and information when I’m driving. I also wanted to use it on my motorcycle, but wasn’t ready to shell out 600 euro’s for the occasional bike trip. Compared to the 600 euro’s I had financial room to screw up three 200 euro TomTom Ones :-), so I had a go at one, and here’s how it worked out.

TomTom OpenedFirst I opened it up and looked for a spot to place a 3.5mm earphone jack. There was (ver little) room at the bottom of the unit just behind the SD slot. An ordinary 3.5mm Jack wasn’t going to fit, so I canibalized my iPaq for a small 3.5mm connector. Some careful measurements later, I decided it would fit, and started the electrical investigation before drilling holes in the unit.

SchematicI cut the read wire to the internal speaker and tried a couple of resistors in series with my earphones to get the right audio level. With the earphone’s left and right speakers in series, a resistor of 470 Ohms sounded nice. Loud enough to be heard on a motorcycle, not so loud it would ruin my earbuds and -drums, and the volume slider controls the volume nicely. As you’ll see this is an unorthodox connection for earbuds, since the ground lead is not connected. It is a matter of choice, you can connect the earbuds in parallel if you like, the impedance only changes a few Ohms. Compared to the 470 Ohms resistor you will probably not notice the difference. I didn’t bother to change it.

In the 3.5mm plug from the iPaq there is a nice switch to disconnect the internal speaker. When I insert the earphones, the internal speaker is turned off, just like you’d expect.

With all planning and preparation done, it was now time to drill the hole in the TomTom case, the official point of no return. After the drilling, removing the battery and some fiddling with glue, the connector would not sit still while the glue was drying. I taped it to the base so the glue could settle. Be careful not to smear glue into the 3.5mm connector, the casing is not 100% closed because of it’s size. You can actually see the metal of the connector for the left earphone piece in the picture. Glue that and you have a useless connector.

After the glue dried, I reinstalled the battery with a fresh piece of double sided tape, and did the wiring properly. To prevent wires and the connector from hitting the copper shield of the circuit bord, I strategically placed some isolation tape on the bare soldering joints. After that, the TomTom could be cloded up.

Modification, bottom viewAs you can see on the right (click on it for larger image), the end result is pretty neat. As it turns out, the connector is not in a very different spot compared to the older model TomTom one. I tried it on my bike today, and it works nicely. I put the TomTom in a pocket of my jacket so I can not see or touch the display, but the spoken instructions are good enough compared to the money it cost me to do this (10 cents for the resistor, not counting the 3.5mm jack I got from my iPaq). You can hear the instructions while driving 120km/h on the freeway, unless you’ve got very loud pipes…

Now go and roll your own!

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25 Responses to TomTom One v2 earphone modification

  1. garret says:

    This is really interesting and something I would like to try.
    I have the ONE v3.

    Could you repost the schematic as i can’t think link to the large image is broken.
    What level of electronics tech ability would you say this job required? Is it something I could get a more knowledgeable friend to do fairly simply (without a great risk of bricking the device)?

    Thanks for your help.
    Garret

  2. rolfje says:

    Hi Garret, I fixed the link. You do not have to be an electronics expert to do this, as long as you carefully follow the schematic you should be fine.

    The real risk in doing this is damaging the device while drilling holes and removing the battery. Insulate the joints carefully, it’s easy to shortcircuit stuff when closing it all up. There is not much room in there.

    Take care,
    Rolf

  3. DaveH says:

    Hi. Inspired by your ‘how-to’ i opened up my defunked ipaq 2210 and nicked the headphone socket. I’ve studied your circuit diagram but can’t understand how to wire to the connector to achieve the circuit, particularly the switch portion. One side of the switch is permanantly connected to the ‘tip’ of the 3.5mm jack, how do you put the resistor in series?

  4. rolfje says:

    Hi Dave,

    As you can see in the schematic here https://rolfje.files.wordpress.com/2007/10/o_schema-tomtom.jpg
    one side of the switch is connected to the resistor. If this is is also the tip of the jack, then the resistor goes between one of the channels and the 2-pin connector.

    In a series connection it does not matter where the resistor goes, as long as it stays in the same series (left side of the schematic). Another tip is that the “ground” is shared between L and R, but I didn’t connect that. So the jack’s “ground” pin is actually the wire between the left and right speaker in the schematic.

    Does that help?

  5. DaveH says:

    I’m still somewhat confused!! The circuit i ended up with is very similar but must differ somehow: I broke into the +ve speaker wire and put this to the ‘tip’/switch connection on the socket. The connection on the other side of the switch I connected back to +ve speaker. That took care of the speaker switching. I joined the +ve on the ‘tip’/switch connection to the ‘ring’ and joined the ‘sleeve’ to the resistor and then to a T in the -ve speaker. So, when no earphones are inserted, the current is routed straight thru the switch and on to the speaker. When earphones are inserted, this path is broken and the speaker is cut out/turned off. The current then passes in parallel to the L and R earphones via the ‘tip’ and ‘ring’ connections and the ground of both earphones connect back (via the ‘sleeve’) via the resistor, back into the -ve. That works fine when inserting earphones, it also works well when inserting a connection to my motorcycle intercom system but only if the sat nav is running on battery. If i insert the sat nav charger, the result is clicks and pops at the beginning and end of each instruction.

    Anyway, I’ve had a change of plan, I bought a very cheap satnav (with earphone socket!) and modified it to run, how shall we say, a more familiar satnav solution. Problem solved! Thanks for your help anyway.

  6. rolfje says:

    At the time of me making this mod, the USB adapters were not available/supported. Looks like a much better alternative indeed! Thanks for the link!

  7. simon says:

    So how would the Mini U.S.B Connector help over the previous modification? It still has to be connected to the speaker inside the unit as described doesnt it?

    I have the same TomTom, but without the card reader slot.
    Do you know if anyone has done your wonderful conversion with this unit?

    Thank You!

  8. rolfje says:

    No, from what I understand, there is an USB to earphone adapter which doesn’t require modifications to the TomTom. I have not actually seen this adapter myself, so maybe it’s a myth.

    Other than DaveH, I have no confirmation of anybody doing this modification. But then again, you’re not required to reply ofcourse 🙂

  9. andy says:

    have only just found this site
    hope i am not to late with my reply
    i also want to use my tomtom xl v2 on my bike as well as in the car
    i wondered if this might do the trick?
    http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=350185486725&ssPageName=STRK:MEWAX:IT
    have emailed the seller and am awaiting a reply
    no way am i forking out the £350 plus for the tomtom rider

  10. andy says:

    the ebay listing was for a lead similar to this
    http://www.mobilefun.co.uk/audio-adapter-enhanced-mini-usb-p12552.htm
    but it also had a female mini usb atttachment to plug the charger into
    i am not convinced it wiill work?
    somebody must have tried it????

  11. Ken says:

    Can all please note : There is NO audio out from the USB connector on a tomtom one V2. The connections at the base of the tomtom in the USB socket are : 5v charging , ground , and 2 more pins for data IN/OUT. So any leads you see on ebay or otherwise will not give you audio out from this model of tomtom via USB……. I did a modification on My tomtom one V2 for use on my bike . It’s very simple . Get a lead with a 3.5mm bonded socket on the end. Cut the other end off to leave bare wires. Drill a hole in base of tomtom to allow lead to go through to inside. Solder the 2 bare ended wires to the speaker terminals. Fit a tywrap to cable inside tomtom to stop it being pulled out through the hole. Now you can plug a 3.5mm plug / earphone in to the trailing socket. You now have audio out to your earphone . sorted !

    • rolfje says:

      Please note that with your solution, you’re putting more load on the audio driver chip. The solution in my blog switches between speakers and earbuds, maintaining correct impedance.

      It’s also nice to have your speaker silent when you use the earbuds.

      • Ken says:

        Hi rolfje , I have the greatest respect for your blog. I didn’t wish to detract from it’s correctness or the information supplied. You are right , it is nice to have the audio silenced from the internal speaker. My comment was simply to inform anyone who might doubt their own capabilities to do YOUR circuit / modification that there was a more simple way if they could’nt manage your mod. The change in impedance by connecting straight across the internal speaker is negligable and the user will more than likely be reducing the volume ( for the earphone ) which would result in lowering the load on the audio IC. The EUA6204 audio chip is capable of 1.36 watts and is pretty much bombproof as far as overload is concerned. To be more ‘purist’ the audio could be passed via a small decoupling capacitor but again , simplicity was the aim. I have several friends who have done the mod this way and been using their tomtoms on bikes for the past 2 years without any problems. for anyone out there thinking of modifying their TOMTOM , do it rolfje’s way if you can.

  12. Rob says:

    Hi Rolfje,

    I would also like to add an earphone into my ONE XL.

    If I just splice an old headphone cable into each side of the speaker in the XL, and put a resisitor ‘in-line’ on one of the cables to the speaker , will that work ? (I’m not worried about the sound coming out of the speaker as well as in the headphones)

    Cheers,

    Rob

  13. Prit says:

    Hello,

    Why all this, ? at the bottem on your tomtom it says, “bleutooth”, you can use a
    bleutooth headphone set on it.

    I’ve got a tomtom one as well, no bleutooth on it, so I had to made an extern plug on it, no problems with the volume, you can change your volume “on screen” on your tomtom, easy enough !

    greeeetzzzz, S.

    • rolfje says:

      Because a bluetooth headset to mount in a helmet for use on a motorcycle was not exactly cheap at the time I wrote that article. And they still aren’t, and I also don’t like the big blob on the side of the helmet.

      Today I have a Garmin Zumo 660, but still use Bose earbuds because they’re cheap, sound great, protect my ears from noise, never run out of batteries and always work. Luckily the Garmin comes with a nice set of cables which put the earphone jack right underneath your seat so it’s easy to plug the earbuds in. I’m a happy camper.

      Cheers!

  14. Floyd Vahalik says:

    You told us everything except how to get the Tomtom apart. How didi you do this?

    FAV@bdhsi.com

    Thanks, Floyd

  15. Tanny Lee says:

    I worked with this idea, except I extended the wires, passed them through a small incision in the left hand corner of the unit’s bottom and attached my female stereo jack externally. I am using my unit hooked into a car stereo system, now I can navigate at higher speeds with my windows down and navigation volume set as I need, its so good to now have access to both sound and charging and I especially like that I don’t have to be checking the visual monitor which I find very distracting and downright dangerous in heavy traffic.

    Thanks a bunch.

  16. a small incision in the left hand corner of the unit’s bottom and attached my female stereo jack externally. I am using my unit hooked into a car stereo system, now I can navigate at higher speeds with my windows down and navigation volume set as I need, its so good to now have access to both s

  17. Edaordo says:

    Hello everyone,
    I’m not expert electronics so I followed the Ken’s advices closed by soldering two wires bare to the speaker terminals. Now when I try to turn on the tomtom it off right away or if I can turn it switches itself off during the first loading screen. Can anyone help me?

  18. Will says:

    Thanks for this info. I had a Tom Tom laying around and did the modification as shown but with a twist: I bought a $15.00 Bluetooth transmitter that plugs into the new jack and syncs with my SENA in-helmet Bluetooth intercom (model 10c). Works a treat.

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