Power Connector

[majestic100]

I'm wondering if someone can help with pinouts

Friend has given me his (broken) in car charger, for TomTom ONE v3, plus a new mini-usb 5 pin plug to attach to power cord for me to repair. He removed damaged/broken usb connector on power cord without noting pin connections.

The power cord has 3 wires; Red, Black and Green. I'm assuming Red is +5v and Black is ground. Don't know what Green is for?

From what I've found out, the mini-usb pins are numbered 1,2,3,X, and 4. Pin 1 is +5 (Red) and pin 4 is Ground (Black). Green is shown as pin 3 (Data+).

I'm thinking connecting to pins 1 and 4 is correct but unsure of the Green wire and what it is for does and which pin to connect.

Can someone help ?

 

[canderson]

The third wire is what's known as a "remote sense" wire. It looks at the voltage at the far end of the connection and adjusts the output of the charger accordingly. Evidently TomTom worries about voltage drop along the length of their charger cables.

I've never tried to open up the connector. They're molded onto the cable, and I can't imagine how your friend actually disassembled it apart from judicious application of an X-Acto knife.

There's no question that the +5 and ground will be located in the two standard positions for those lines on any USB connector, and it's very hard to imagine that the remote sense wire would be placed on either of the data lines. One can only imagine that it's on the "other" pin.

That lead is important to the way the car charger works, so it mustn't be left off. As I recall, leaving it open results in the charger maxing out the voltage to the unit - not a good thing. I recall some time back that users would report dead units, only to find that this particular wire had broken internally in the cable.

Here's hoping someone either knows for certain, or is prepared to sacrifice a cable to find out, but as I said, I can't imagine how your friend canopenered that other connector. Are you sure he didn't just cut it off the cable, and that perhaps you could still ohm out the 3rd wire from what's left?

 

[majestic100]

Many thanks for your response. Contacted friend whose just phoned back. Yes........He cut off the end stripped back and soldered ends of wires but bottled connecting to new mini usb. He never thought to open up old mini usb end before he binned!

The new mini usb comes in "self assembling pieces".. The pcb part has the 5 pins but 4 solder connecting pins. I've buzzed out to find which one not connecting.

As indicated in previous post, the 5 pins are as described at http://pinouts.ru/Devices/mini-USB_pinout.shtml; Pins 1,2 ,3 and 4 are connected to the solder connecting pins the X pin is not connected. The x pin as article states...."May be N/C, GND or used as an attached device presence indicator (shorted to GND with resistor)"

This falls into line with your remote sense so thinking this is where green wire should be connected ???

 

[majestic100]

OOps!!! bit of an error last post, brain not in gear...........

The X pin has no connection to any of the 4 solder pins, These are +5, D-, D+ and GND. Thus still not sure where to connect Green wire from charging unit. If following color coding of schematic then would be pin 3 (D+) but.............

 

[mikealder]

The sense wire is simply soldered to the same pin as the red wire goes to.
(I am in the dog-house for the rest of the night, the wife has spent all day cleaning the house, I came in and took a knife to a power lead, result, bits of black plastic all over the kitchen, oh and I managed to cut my finger in the process....) - Mike

 

[majestic100]

Mike,

Thanks for your efforts. Hope you don't remain in the dog-house for long !! and sorry to read you cut your finger but grateful for feedback.

 

[Andy_P]

Here's a little article about the sense wire.

Cigarette Lighter Adaptor (CLA) or No Smoking Allowed. .

It was written for the original Go CLA, where the sense wire was white, but the theory is all the same.

I've never seen a re-wireable mini-USB plug...
If you end up having problems with it, the alternative way forward could be to cut the end off a normal USB to mini-USB lead and wire it into the CLA with the sense input connected at the PCB as per the article.
That means there is no account taken of any voltage drop down the cable, but the author found it made no practical difference.

 

[majestic100]

Andy,

Thanks for info. New mini usb comes in 4 pieces; very fiddley. Had a go soldering up but not very happy with end result. Putting altogether I sense that case and soldered contacts touching. Wouldn't want to test on TomTom. Understand now why my friend reluctant to do himself. Spoken to him, told him situation and my feelings and suggested he buys himself a new charger. He's agreed to do this and told me to bin old one. Result!.

Thanks to everyone for feedback on the problem; all very interesting