Fixing a TomTom Go 510/710/910 that has been connected to 12V

This page explains how I fixed my TomTom Go710 after (stupidly) connecting it to a 12V in-car DVD power cable

After connecting my TomTom Go 710 to a 12V power supply it gave out a little smoke, a small pop, and stopped working. I then read the instructions, and noticed that it's supposed to run on 5V, not 12V. Since then I've also heard of a fault with some of the 5V power supplies which can results in 12V output, which would give the same result - a broken GPS.

After a bit of research, I found out that it was likely a couple of chips on the main board would have blown. I'm not much good at soldering, so didn't expect to be able to fix that, but tried to open it anyway to take a look. The first problem I found was that it's all held together with Torx screws, and I didn't have anything small enough to fit it. That was quickly solved by buying a precision Torx screwdriver for about £3, and it came apart quite easily.

It was then clear that a few bits had burned quite badly. However, everything else seemed good, so I decided to look for a TomTom with a broken screen and put the two together. I found a TomTom with a broken screen on eBay for about £10, and when that arrived took it to bits and confirmed that it looked good.

I managed to combine the best bits of the two devices, and ended up with a working TomTom again for about £15 total. It was a bit fiddly, but nothing was particularly difficult.

Here are the steps I followed

Remove the four Torx screws (circled in this picture), after removing the two rubber strips on the back. With the proper screwdriver, these came out very easily. I could then push out the innards by pressing on the back just underneath the connector. Back of a TomTom Go 710

The top board just plugs in to the main one, so can be removed easily after removing another 2 Torx screws. Burned TomTom board

Remove the main board after undoing four more screws. There were quite a few bits burned, so it was quite clear why it didn't work any more. Burned TomTom main board

Disconnect the ribbon cables, power cable and speaker cable. The power and speaker cables plug into connectors underneath the board, and can be levered out quite easily with a small screwdriver. The ribbon cables are held in place by a small brown plastic strip. Push up on the tabs at the points circled in the picture to release it, but be careful not to break the plastic strip, although if it pops out of the connector you can just push it back in. TomTom ribbon connector

Reconnecting the cables to the new board is a bit fiddly, basically it's the removal in reverse, you need to slip the ribbon cable into the connector, on top of the brown plastic strip, then push the strip down to hold it in place. Practice on the broken bits of TomTom to get it right. Pushing in the power and speaker connectors is fairly easy, but you might want to unscrew the speaker to give you a bit more room for manoeuvre.

Once you put it back into the case and put it together you should charge it up for a few hours then switch it on.

Unfortunately, I found out there was a problem with the donor device, someone had broken the reset switch by pushing it in too hard, so it was permanently stuck on. That meant the green power light would only come on when pressing down on the power switch, but would go straight back off again. I fixed that by prying off the top of the reset switch, I could probably have soldered on a new one but didn't bother since it works OK without it. Position of reset button on TomTom Go 710 board

If the reset button is working, you can press it in with a paper-clip as shown in this picture. You should feel it click as it is pressed, and jump back a tiny bit as you let go. Don't push it too hard, or I guess it will break. Pushing reset button on TomTom Go 710 with a paperclip

The device ID had changed, so I had to re-register the maps with TomTom.

Apparently the battery in these devices only lasts a few years, so I kept the original one in case I needed it. This picture shows its location (circled), you need to remove the LCD screen to get at it. Position of TomTom Go 710 battery

In fact, after about six months the battery did go. For a few weeks, the TomTom kept on displaying a red battery outline, so I tried leaving it on charge for about 24 hours. That didn't seem to do any good, in fact it seemed worse, and after another week or so it wouldn't switch on at all. However, the green charging light would still come on when the power cable was connected. It is quite a fiddly job to replace the battery, you need to take it out of the case, unscrew the mainboard from the top and disconnect the power and speaker cables, although you don't need to disconnect the ribbon cable. Then lever out the LCD screen, being careful not to force it too hard, and remove the black rubber "matt" behind it to see the battery. A couple of thin metal clips hold it in place, but you should be able to remove it by putting a screwdriver at one pole and levering it out, manouevring it around the ribbon cable.

After replacing the battery it worked just fine for a few weeks, then started to fade again. Then I noticed that it was not necessarily charging, even when the green light was on. If it's not sitting solidly in the mount, the battery doesn't charge, so I cleaned up the contacts, tightened up all the screws and tried it again. It didn't really make any difference, but I found that by adjusting the angle of the mount so that the TomTom was pressing down on the connectors it started to charge again.

And then it started to get more and more difficult to charge. The problem is with the soldering between the connector and the main board, so I'm going to have to open it up again and solder it into place. This seems to be a fairly common problem with the TomTom Go x10, it could probably be avoided by making sure the board is very tightly screwed on to the body when re-assembling. This is the TomTom Go connecter that gets loose and needs to be resoldered.

In fact my soldering skills weren't good enough, so I decided to connect some wires to the battery to allow direct connection to a 5V supply. Of course this is likely to reduce the life of the battery, and increase the risk of it exploding or going on fire but I only connect it for a few hours every now and then. I connected a couple of wires to the battery connecter, just slotting them in as shown. I used thin copper telephone wires. TomTom Go 710 Battery connecter with additional wires.

There is a handy hole in the back of the case where I fed the wires out, and now I can connect them up to a 5V supply when I want to charge it. Charging wire coming out the back of the case.

This worked fine, but recently someone pointed out that there's a better solution with just a little soldering. If you solder a +5v supply to one end of the mount connector (the one at the same end as the aerial connector), and another one for the -ve voltage at the other end (or on any of the ground lines around the edges of the board) you can charge the battery properly. There's a handy hole in the middle of the circuit board which you can use to feed the wire back up through, and can then feed it out of unit fairly easily. I tried this a few years ago now, and can confirm that it's still working fine. I've fed the wires back into the connector mount, and soldered them to the 5V input socket, so can now charge as before.

Here are some pictures of a more elegant solution which were sent to me, the +/-ve wires are soldered to the points where the connector was and then the wire is fed out through a hole drilled in the side of the unit and connected up to socket for 5V connection at the other end. +ve/-ve wires soldered to the board where the connector has been removed.

Back view

Side view

Connector at other end of the cable.

View from inside.

Just in case you want to know what the board should look like, here's a high resolution picture of TomTom Go 710 board

The components which have likely blown are: