740 Battery Problems??

Joined
Jun 23, 2011
Messages
6
I just received a refurbished 740.

As soon as I plugged in the AC adapter & charger the orange light came on next to the on button. I let it charge for 8 hours and the light was still orange. Question: Should the light change to green when battery is fully charged?

I drove to work same morning using battery power. The unit was off and in my possession until 9 hours later for the trip home. As soon as I turned it on I got the low battery message. I plugged in the cigarette lighter adapter and was able to drive 30 minutes back home.
Charged the unit all night. This morning the light was orange and the battery indicator appeared to be fully green. I plugged the unit in the cig lighter and left for work. 10 minutes later I got the unit is shutting down in 10 seconds message. I would cancel and 5 minutes later get it again.
Same thing happens when plugged into the PC, shutting down in 10 minutes.
When the USB is connected to the AC adapter or the PC, it is always orange. When plugged into the cig lighter it's green but very faint.
I?m hoping this is something I can fix. Any suggestions are appreciated.
 
I would try a different cable for the connection to AC and computer. Are you using the cable provided by TomTom or a different one? Sometimes, that makes a difference.
 
Indeed the indicator around the on/ off switch should turn green when the battery reaches full capacity, it sounds like your battery is dead, here is how to change it, please consider this was a 940 Live so there might be a few changes, for example your unit won't have the FM Tx board in it but otherwise it should be the same:

With the x40 units age increasing its only a matter of time before the charge retention starts to fail, this shows how to get in to the device to swap out the battery but along the way it looks at some of the technology employed within the device.

If you don't know how to handle taking electronics to bits please leave this well alone as you could damage your device.

Both side pieces simply unclip from the device, you will need strong thumb nails to get these out though, once removed there are four Torx head screws which are securing the device together.

img9646y.jpg


Before we take the screws out a closer look at the right hand side strip now its been removed, this contains two ?windows? the upper on being a simple hole from the microphone, the lower one is the ambient lighting sensor. Interestingly this is a short length plastic ?light pipe? which is employed to carry the light to the sensor which is buried within the device. These light pipes are more often used to feed light to a front panel indicator, and this goes someway in explaining the poor performance of the light sensor when you put the device in demanding conditions (low sunlight dawn/ dusk) I am not even sure this light sensor hardware is even used these days for switching the colour scheme as its more reliable to use the time of day, date and position to work out when the device should switch between lighting modes when set to automatic.

img9647h.jpg


The black ?doughnut? is the microphone, the small white blob to the right of the microphone is the light level sensor, it is a tiny component only a few millimetres across.

img9648s.jpg


What?s inside the device? With the four corner screws removed the rear case is easy to remove:

img9651x.jpg


Joining the two halves of the device is the red and black twisted cable on the right, this is the microphone cable and a much larger multi-way ribbon cable. Running left to right along the bottom of the picture is the Sim card slot, the main docking connector, the memory card holder and finally the battery connector. With all the main chips now encased in RF cans there is no ?tin foil? like used to be found in some of the earlier devices.

img9652m.jpg


With the battery connector disconnected first the ribbon cable and microphone can be released, this allows both halves of the unit to be separated, above is the screen portion. Surrounding the on/ off switch is another ?light pipe? (lower right corner of the above picture), this is what illuminates red while the device is on charge and green when powered externally and fully charged. It is possible to split the above assembly down even further, the screen is released from the front as it is simply clipped in place.

img9665j.jpg


To extract the main board you have to remove six torx screws, one is partially hidden under the black stick tape to the right of the speaker. Note the screw lower right corner is also used to connect the small FM Tx aerial board to the main PCB (Where applicable, 940 only). Make sure you disconnect the battery (upper left) and the speaker plug which is just to the left of the speaker. The PCB is secured to the case with two slots at the bottom of the board either side of the docking connector, lift the board slightly at the top before it can be simply lifted out of the housing.

A view with the board removed showing the GPS patch aerial:

img9656m.jpg


The other side of the PCB, where you can see the HD Traffic receiver, the lower number on the bar coded sticker (top left) is the units IMEI so don?t go showing that in pictures. Again with all the chipsets under metal screen cans there is very little to see.

img9659j.jpg


I mentioned the single wire connected to the main PCB via a mounting screw, attached to the other end of the cable is this small FM aerial board, see Here for product details. It would also appear the GPS Patch aerial is from the same company when you look at the product range. NOTE this FM Tx aerial is ONLY fitted in the 940 none of the other devices have this hardware which explains why you cannot use FM Tx on anything other than the 940.

img9661.jpg


And finally the battery, it is glued into position but can be easily removed, at least they have stopped the rather silly idea of gluing the battery to the main PCB!

img9662b.jpg


img9663u.jpg
 
I guessed as much. I order a replacement battery and should have in a couple of days. Can you say which part of the side covers come up first? Inside or outside? What tool do you suggest using to remove them?

Thank you..
 
I ordered a new battery just in case but will try a different cable as well. It was a refurb unit purchased from Ebay. I assume it was from TOMTOM but can't verify.

Thank you..
 
I just sprung the side parts out using my thumb nails working along the outboard edges i.e. the side furthest away from the screen.

One thing I should have mentioned is the battery lead, its part of the battery and on Live equipped models they emply a five wire battery, on non Live models it seems to be a three wire battery. Most third party batteries are only supplied with three wires but you can cut the old battery lead off and solder it to the new one just match up the colours of the cables, if you do get a five wire replacement battery please let us know where its from - Mike
 
Love the way they put a big "100%" sticker right over the connector in the eBay site picture, so you can't tell what it looks like. :rolleyes:
 
What's struck me as odd is that the 740 and 750 models are getting a somewhat weenier 1100mAh pack (it's not just that ebay listing - it's the same everywhere I've looked) vs. the 1300mAh pack that came in the previous 720/730 devices.

The old 1300mAh packs shipped under the part numbers
AHL03713100, 1697461, VF8, and AHL03714000.

The new 1100mAh packs also come under the numbers
[FONT=Verdana,]VF1A, AHL03711012, HM9440232488, and 4CP0.002.06.

I have no idea what number variations were happening due to 3/5 wire versions for the Live model. Anyone still have two to compare?


I can't see any real difference in any of the photos.


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