740 "Active Dock"

[canderson]

I think the "Post Man" should have the answer to your problem, although they said four or five days to ship it over so I guess its not turned up yet?? - Mike

No, not yet, but you have no idea what a boon that delivery will be. Although it's at least a 4 layer board, it appears fairly simple, and I'll be able to trace back from the audio connector to the docking connector and determine what was in between. Thanks again, Mike!

 

[hap]

Tomtom 940 dock with audio

I have been following your discussions intently, and was hoping if someone knows the answer to my proposed solution.

I have one of these for a tomtom 940.

I am considering buying one of these and swap over the two dock components. My aim is to get audio out from the tomtom 940 to my car head deck (which has audio in) using the windscreen suction cup mount.

Hence my question, are the heads easily swappable in this way?

 

[canderson]

I think you've got the only practical solution there, hap. The mounts will be readily interchangeable. You'll find them quite easy to swap. [ignore this!] That said, you'll need to drill a pair of holes in the rear along the same line as the USB connector for clearance of the two jacks - they pass through (but not beyond) the case, and you'll be needing at least the end one for the 1/8" jack anyway. It'll be obvious when you have the little PCB in your hands.[/ignore this!]

I am having a BUGGER of a time finding that 1/8" connector. It's an SMT 3 circuit 5 pin with "2 switches". Easily found IF you need normally closed switches (where the installation of the peripheral device's plug disables/disconnects speakers or something similar). The mount requires normally OPEN switches that close when the 1/8" plug is inserted. I'd much rather do conversions with SMT than trying to sort out wiring in a panel mount, but ...

 

[mikealder]

Indeed you can swap the mount "shoe" from the Brodit clip syle unit to the Windscreen sucker if you really want to, I have even posted up some instructions with pictures showing how to do it (somewhere on the site).

The Brodit style mount is listed as having the iPOD connector and Line Out socket so there won't be any drilling of the housing needed (unless of course the information on the TT web page is incorrect, AFAIK the Brodit style units are all supplied with the three sockets on the back - Mike

 

[canderson]

... so there won't be any drilling of the housing needed (unless of course the information on the TT web page is incorrect ...

No, my mistake. Was inserting my own recent "swapping" experience <g>. If he's swapping just the fixed mount for the suction mount and leaving all else intact, there won't be any need for drilling anything. The dock on the fixed mount already contains everything he needs.

Still on the hunt for SMT 1/8" jacks with a pair of N.O. internal switches, though.

 

[dhn]

Canderson, I have no clue about any of that stuff but does this link make any sense to you?

DC 3, 1 SPACE CEM-1 8, 5-5, 8, MIC SISONIC SMD 1, FAN 12VDC 1, 3V 0

 

[canderson]

Yup. DigiKey is one of the first places I tried before heading to specific manufacturer sites. The one below from CUI is close to what I need, only the "switch logic" is reversed and the pin spacing is a tad off. I need for the two internal "switches" to be open until the 1/8" plug is inserted, not closed until it's inserted. There's the rub. Once I've got that sourced, I could start modifying the U.S. model for TT users to supply audio out on the 740.

Digi-Key - CP1-3515SJCT-ND (Manufacturer - SJ1-3515-SMT)

 

[hap]

TT Audio

Thank you all. Good to know I am on the correct track.
Mike - I found your descriptions of doing the conversion, but could not see the pictures. Seems my work filters pictures.: (
I'll find a suitable unfiltered way of looking.

Canderson. Is something like this what you are after?

 

[mikealder]

@hap, if you are still struggling to see the pictures then send me a PM with your e-mail address and I will send over a Word document with the text and pictures embeded for you to view.
Swapping over the "shoe" from one ball to another is easy when you see how its done but you will need some Torx drivers and small Philips screwdrivers to acheive this - Mike

 

[hap]

Hi Mike. Thank you for your kind offer. A simple solution was to use my home PC - and I was able to see all the pictures you kindly posted. Thanks once again.

 

[canderson]

Canderson. Is something like this what you are after?

Generally, yes, but it needs to be an SMT part, and again, instead of having N.C. switch contacts, it needs to have N.O. switch contacts that close when the plug is inserted into the jack.

On the board, there are 5 contacts on the existing SMT connector.

Pin 1 (sleeve) is the audio ground back to the TomTom. When an 1/8" plug is inserted, Pin 1 is connected to Pin 5. When it's not plugged in, the two are not connected (hence the term "normally open").

That ground that inserting the plug causes on Pin 5, through a 220 ohm resistor, pulls a circuit low on the TomTom to indicate that there is a plug connected -- which is how it knows not to go ahead and route audio to the speaker if you unplug, even if you have the config set to send the audio to the line-out connection. I don't think I've ever seen a stereo connector with the sleeve (ground) switched like this before in any connector. It's always the tip and ring that are being switched.

There's also a Pin 2 / Pin 4 issue, but I think I can work around that easily enough.