bigandy
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| posted on 22/2/08 at 10:28 AM |
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TomTom One DIY repair info.
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
Dammit! Too many decisions....
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tegwin
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| posted on 22/2/08 at 10:38 AM |
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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
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Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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Mr Whippy
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| posted on 22/2/08 at 10:41 AM |
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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]
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charlierevell
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| posted on 22/2/08 at 10:43 AM |
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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.
Tango orange is an 'IN' colour!!
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tegwin
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| posted on 22/2/08 at 10:46 AM |
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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
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Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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02GF74
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| posted on 22/2/08 at 10:53 AM |
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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?
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tegwin
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| posted on 22/2/08 at 10:57 AM |
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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...
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Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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ChrisW
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| posted on 22/2/08 at 11:44 AM |
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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]
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MikeRJ
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| posted on 22/2/08 at 11:53 AM |
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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.
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muzchap
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| posted on 22/2/08 at 01:03 PM |
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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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If you believe you're not crazy, whilst everybody is telling you, you are - then they are definitely wrong!
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tegwin
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| posted on 22/2/08 at 01:13 PM |
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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!
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Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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BenB
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| posted on 22/2/08 at 03:13 PM |
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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....
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MikeRJ
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| posted on 22/2/08 at 06:27 PM |
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quote:
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
If this diode is placed across the supply rails to protect from reverse polarity then bridging it isn't really going to help!
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