Morning all.

I was just wondering if anyone is familiar with the TomTom One internals? I have one that is refusing to power up, either on external power, or on the internal battery.

I suspect that it has been plugged into the car power supply, with it set at the wrong voltage, or possible the wrong polarity. I have taken the back off, and had a look, and there is one burned component (D2 on the power board) and no other obvious damage.

Has anyone got any ideas for a cheap, or DIY repair, or is it properly shafted and not worth repairing? It is the v1 version too by the way.

Any help would be appreciated, thanks.

Andy

Im assuming that D2 is a diode...

So its possible that this burned out before anything else did...

however, with all the delicate electronics inside, its quite likley that some of the chips will be FUBAR!

You could always try and replace D2 with another diode..

Carefully solder it in...might work again

I doubt you could fix it as these modern things have such tiny little components (opened up my I-pod to dry it OMG the components are like dust specs!)

[Edited on 22/2/08 by Mr Whippy]

Just to check you reset it all before you took it apart? They can quite often freeze and not want to turn on or respond to anything.
Being that you've found a burnt diode its probably no the case, but mine does it quite a bit.

If you are very carefull you can replace surface mounted components...especially the bigger ones like input diodes...just be carefull not to get anything too hot..or spill solder all over the place

any sensible design would have a diode in the power input to prevent damage to the electroice should the unit be powered with reversed polarty supply.

.... but that hsould not burn the diode out.

that could well happen when the voltage is too high but does not bode well for the electronics.

assuming it is toast, you have nothing to lose by replacing the diode; presumably the costs to have a perfeshional look at it is more than a replacement unti could be bought for?

Do they still sell that model?

If so, just go buy a new one....Put the broken one in the new box and then return it to the vendor asking for a refund.....save the hassle...

I've just fixed a DAB radio that had the same problem - burnt diode in the rectifier bridge. Actually the transformer had gone too, so my guess would be that it belted out a bit of mains voltage into the PCB as it gave up the ghost.

Anyway, new diode and transformer, and all was well - no damage to the rest of the system. Well worth the £18 I spent on ebay for the knackered receiver!

What I'm trying to say is... if it's dead already, you've got nothing to loose. Swap it out and see what happens. Just be aware that if you've not done work like that before, probably best to find a mate who is handy with a soldering iron to do it for you.

Chris

[Edited on 2/22/2008 by ChrisW]

Does the green light come on when you plug it in to the charger?

It's very, very common for older TomToms to be damaged by people using the incorrect charger, or for the charger itself to become defective on earlier models. Depending on the model of One you have, check IC's U24 (TPS62000) and U25 (LTC3411) for signs of destruction (usualy a white spot on the surface). They are available from Farnell, but they aren't particularly cheap, and you'll need a very small soldering iron (idealy an SM rework station) and microscope to replace them.

The cheapest and quickest way to check replacing the component is to 'bridge' it.

get a piece of wire and place each end across the diode - so it bridges the knackered component - if it lights up and works - may need assistance turning it on whilst you hold the wire - cool - solder a new diode in.

That's the quickest way and the way I would do it

I'm not saying it's the best way Just locost and quick

If its just an inrush diode to protect the circuit from reverse polarity, you could bridge it providing you are 110% sure that your power supply is of the correct voltage and power supply..

IMHO....I wouldnt do it!

Yes, by all means bridge it with another diode though!

Just be aware that if you bridge the diode the components downstream will be seeing a higher voltage than intended due to the lack of forward voltage loss. The drop depends on the type of diode in question....

Probably won't be a problem... But don't blame me if you let out all the magic smoke....

quote:

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Originally posted by muzchap
The cheapest and quickest way to check replacing the component is to 'bridge' it.

get a piece of wire and place each end across the diode - so it bridges the knackered component - if it lights up and works - may need assistance turning it on whilst you hold the wire - cool - solder a new diode in.

That's the quickest way and the way I would do it

I'm not saying it's the best way Just locost and quick

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