Connecting Power causes TomTom to loose TMC signal

crich · Occasional Visitor Joined: Jan 27, 2008 Posts: 5

I have noticed that I lose the TMC signal when I connect power to my TomTom Go520. Works ok(ish) on internal battery.

I have a new GO 520T (Jan 08). As an experiment I parked at a point where my tomtom connected to TMC while running on battery, I then connected power and the TMC connection failed. I then took the tomtom and TMC aerial out of the car (with power still connected) and on holding the aerial up obtained a connection to TMC.

It would seem that the TomTom can lock onto TMC signal with power but only if I stand outside the car. :-)

To be fair, I have managed to connect to TMC whilst driving with power cable connected , but the signal is quickly lost and connection infrequent (3 or 4 times in a 200 mile trip).

It's worth noting that the power cable needs to be plugged into the cigarette lighter socket to see this effect. If I disconnect the power but leave the cable plugged in at the Tom Tom end, I can receive TMC ok.

I wonder if those who are having trouble connecting to TMC signal have tried to see if unpluging power improves their reception.

It would also help me decide if I need the unit looked at by Tom Tom.

mikealder · Posted: Sun Jan 27, 2008 7:13 pm Post subject:

I assume you have only tried this with the cars engine running? - can you repeat the test with the ciggy charger socket powered up and in use but with no engine running, this way the TT is being powered by a pure battery and its own charger circuit.
This will allow diagnosis of a faulty charger lead or car borne (engine related) interference - Mike

DennisN · Posted: Sun Jan 27, 2008 7:33 pm Post subject:

This sounds a bit like simple coincidence to me.

We know the RDS-TMC signal is dodgy - every day I get it coming and going as I drive my hundreds of miles. There are surely enough people driving just on GO520 battery power to have told us they never lose signal and for us to twig this explanation?

I myself always have my devices powered from the ciggy lighter - no way it would run all day on battery. I switch everything on and wait a second or two for the RDS-TMC to connect itself, then drive off (probably it connects whilst I'm fiddling about setting the route). It loses signal when I drive past the local swimming pool and comes back again somewhere later on. When I went to Ipswich on Friday, it came and went throughout the journey. Even TomTom admit the signal is less than perfect in UK.
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Dennis

If it tastes good - it's fattening.

Two of them are obesiting!!

crich · Occasional Visitor Joined: Jan 27, 2008 Posts: 5

The static tests which I have tried in 3 locations have been done with both the engine running and the engine off. Same result. As soon as I plug the power cable into the cigarette lighter socket the TMC signal is lost. Before plugging in I've noted which radio frequency the TMC is being broadcast on. When the signal is lost I try a manual re-tune but no signal is found. I then disconnect the power supply and re-tune, the signal is found straight away.

I know it's not a coincidence, as I can repeat the experiment every time.

DennisN · Posted: Sun Jan 27, 2008 11:06 pm Post subject:

OK. I'll see what I can do to test my GO920T.
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Dennis

If it tastes good - it's fattening.

Two of them are obesiting!!

Greenglide · Posted: Mon Jan 28, 2008 2:13 pm Post subject:

Well my 520T works the same on battery or via the power lead.

Probably interference from the car's electrical supply not adequately suppressed.

You could try with another power supply - a cigarette lighter to USB and a standard USB cable should do.

Could use a ferrite ring of the PSU lead between the adapter and the connector on the TT unit - this should help. You can get them from Maplin (and similar) which clip over the cable (wound several times) without needing to disconnect the connector at either end.

Equally the same process could be used on the TMC receiver to ensure the noise isnt being picked up there (don't put the ring after the wider bit of cable where the screen stops!).

crich · Occasional Visitor Joined: Jan 27, 2008 Posts: 5

I have resolved this problem by using a new power supply.

I first tried supplying my TomTom with power from my laptop via USB. This solved the problem, so I purchased a new cigar USB power supply and can now recieve traffic info whilst powering the TomTom.

AndyVaughan · Posted: Sun Mar 16, 2008 11:07 am Post subject:

Interesting - what power supply did you purchase?

I have a similar problem and have tried a USB mobile phone charger and it was the same as on the TT charger.

On mine, I only lose the signal in 'weak' reception areas

Andy

gardenshed · Frequent Visitor Joined: Jul 05, 2007 Posts: 466

stuart · Posted: Sun Mar 16, 2008 1:55 pm Post subject: Power supply to 520T

gardenshed · Frequent Visitor Joined: Jul 05, 2007 Posts: 466

just been reading on a German site that firmware versio 7.48 has resolved the TMC problems there, but caused a few more Rolling Eyes

has any one seen an update here for that? i have asked the question there too Shocked

stuart · Posted: Sun Mar 16, 2008 3:55 pm Post subject: V7.480

gardenshed · Frequent Visitor Joined: Jul 05, 2007 Posts: 466

yes just had a reply on the German site saying it was withdrawn because of bugs!!
apparently it was released for a few hours only Shocked

crich · Occasional Visitor Joined: Jan 27, 2008 Posts: 5

So there have been others affected too :-)

I bought my new power supply in Maplin for £4.99.

It's 5v 1000ma. as opposed to the TomTom 2000ma. You need a USB cable too, but I already had one of those. It's sold as being suitable for mp3 players so I decided to risk it. I haven't had any problems with it, and it charges the TomTom pretty quickly.

I have still noticed that in "extremely" marginal signal areas, and I mean extremely marginal, the charger can still interfere,but the improvement over my old charger is probably 99%. I usually plug it in when the battery gets low, as I can run for about 2hrs 30mins on battery even when using Traffic, Bluetooth, FM transmitter and playing my 4Gb of MP3's.

Maybe someone has a more scientific explanation for my problem than my original charger being a dud, possibly the problem (and resolution) is related to the power output of charger. I dunno.

Link to charger:-

http://www.maplin.co.uk/module.aspx?ModuleNo=99487&doy=16m3

portman · Posted: Sun Mar 16, 2008 10:32 pm Post subject:

I had the same problem with a Garmin C510, was never sure if it was the unit or the athermic windscreen, i wasn't the only one. People tried adding magnets to the power lead which seemed to help some people.
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