Tomtom 750 no longer has a charging light

[sherlock]

Hi,

hope someone can help. I bought a relative a 2nd hand Tomtom Go 750 Live. I checked it out and all was fine. Updated maps with no issue. I recharged it on several different occasiosn with no issue.

The relative plugged it into the cigarette lighter via the caddy, possibly with a USB cigarette cable that didnt come with the Tomtom. Now the following happens:

The Tomtom amber/green light on the power button no longer lights up. This is the case in all connection scenarios including:
Tomtom > Caddy > USB to cigarette lighter cable
Tomtom > Caddy > USB cable to PC
Tomtom > Tomtom connector-to-USB cable to PC
Tomtom > Tomtom connector-to-USB cable to USB plug

Also, the PC doesnt pick up the device when its plugged into it

The Tomtom still turns on and works although it is about to run out of charge. The battery charge icon on the screen does not go out when connected to power via any of the above methods.

Could someone confirm for me whether this is likley to be just a failed battery or has something more serious happened on the circuit board that has stopped the Tomtom connector from working?.

Many thanks for any advice you can provide.

 

[sherlock]

I have now swapped the battery over with that of a working Go 750 and proven it is not the battery that is faulty. Is this an expensive repair?

 

[dhn]

Google 'satnav repairs uk' and do some investigating.

 

[canderson]

I have now swapped the battery over with that of a working Go 750 and proven it is not the battery that is faulty. Is this an expensive repair?

Since you have the problem 750 open, have a look at the main board. While we don't see many reports of blown diodes on this model, it's worth a look. Look for a small, charred component. I don't have a 750, so can't direct you to it on the board with any certainty, and the board layout did change a bit over time.

 

[sherlock]

Thanks for the reply. Can't see any charring on the board. Is it possible for a blown diode to short out the circuit to the connector which in turn would stop it charging?. The device is not recognised by the PC anymore, and the "on battery" icon on the screen does not go out when mains connected. The battery fully charged without any issue in the 2nd Go 750 device. In addition, I can see no damage to the connector as a result of misalignment during the seating into the caddy and the connector itself is firm and snug to the main board.

 

[canderson]

Perhaps you can help a bit if we start from the beginning. Device was OK until "The relative plugged it into the cigarette lighter via the caddy, possibly with a USB cigarette cable that didnt come with the Tomtom." So you had supplied the device and the mount, and the relative supplied the cigarette lighter and adapter, and we don't know about the cable?

Didn't have the 750 here, so wish to clarify something ... For desktop use, you have a separate desk dock that plugs into PC's USB, correct? And the same unique docking connector as in the vehicle dock version? (That's how the 740 did it). The 750 doesn't have a 'normal' USB connector available, correct? The whole range of symptoms is bothersome, as though you've now got a major connectivity issue (data and power) at the unit's own connector.

 

[canderson]

Again, excuse my 750-specific ignorance, but as you look around the I/O connector on the board, there aren't any component silkscreen indications that start with "F", are there? I'm sure you'll see a ton of "C" and "R" and "D", etc., but would be interested in anything starting with "F" (e.g., "F1") that might indicate that on this model, they included some sort of inline fuse anywhere. It would only have served as a UL/CE safety device, since it's likely to be SMT and technically not something a user can replace.

 

[sherlock]

Hi.
yes, I supplied the 750 and the mount. The cable is similar to the genuine Tomtom cable, with cigarette lighter at one end and usb at the other that goes intothe mount. Our belief is that the cable has a different voltage or ampage and that has blown something on the 750's mainboard.
The 750 has the same Go Connect (not USB) connector as the 740. So, I've tried a Go Connect cable to a PC, and also to a USB plug. I've also tried with the 750 in the mount and used a USB-to-USB cable to the PC. All combinations show no power light so we can rule out cables or mounts as the cause.
I've posted a picture to hopefully answer your other query. Hopefully the filesize restriction still allows sufficient quality for you to identify what you were after.

thank you.

 

[Arno]

This may be a red herring, but do you have to a USB3 connection on the PC.
I recently read an article about over charging devices.
Didn't pay particular attention as I did not have a USB3 port.

 

[canderson]

Hi.
Our belief is that the cable has a different voltage or ampage and that has blown something on the 750's mainboard.

That would be unfortunate. A cable with USB connectors should, regardless of the item to which it is connected, always be dealing solely with 5VDC. Was the cable that was used hardwired to the cigarette lighter adapter, or was it one of those where the cable and adapter can be separated? What does the adapter say for nominal output voltage and current? Should be a sticker or molded into the case somewhere.

The problem here is that most users have no tool to gain access to the pins of a USB connector without shorting things out, and hence, have no way of checking to see if the output of the adapter is 5VDC as it should be, and even less means for checking that voltage with everything connected and a load on the adapter.

 

[zengshengliu]

I read somewhere that a cheap usb cable could possibly be mis-wired and fried the device
https://plus.google.com/+BensonLeung/posts/EBGMagC46fN
Although this is about the USB type C cable, it could affect the usb cable we have right now. (Good thing Amazon pull those cable from listing)

 

[sherlock]

only USB2 on the PC, and I agree they should all be 5vDC anyhow. The cigarette lighter cable is moulded at both ends rather than one that can have the ends changed. It is a non branded cable and has no markings on it to suggest what output valtage it uses. I guess its easy to say after the fact that maybe it shouldnt be used, yet it has been fine charging mobile phones.

 

[Arno]

@canderson

The ZDNet article
http://www.zdnet.com/article/poor-q...=nl.e539&s_cid=e539&ttag=e539&ftag=TRE17cfd61
is quoting the same Google employee as mentioned already by zengshengliu, above.

 

[canderson]

I'm familiar with that specific problem, but since a Type C isn't going to fit the unit, I discounted that for the purposes of this particular discussion. Not too many microB power problems, though there are some cheap cables that don't move data very well.