Did a COM port mod for my TR451 (pics)

[Raceboy]

Since I got tired of USB->RS232 adapter and did not want to add another card (like PCMCIA->RS232 adapter card), some programs (like VEMSTune which I use all the time) did not work properly and my TR451 is the ultimate power saver, I started looking for other solutions.
I thought about the onboard MAX3243 chip which is for COM port and little googling revealed that I was not the first one who came to this idea: http://www.digital-kaos.co.uk/forums/f3 ... ck-154238/

I went with the datasheet pinout but that did not work in my case (I have R51 Intel motherboard in my T41) and ended up measuring COM port pins (2 & 3 for signal, 5 for GND) with the dock and success! found all the pins.
Fabricated the COM port connector into travel bezel, the connector needed a bit of machining from top and bottom to fit to the ~10mm Ultrabay slot but it did well finally. Soldered the wires and secured them with hot glue.
Apparently one could replace the VGA connector with RS232 connector and have a neater solution but I wanted to keep the VGA connector.

I wanted to perform the same mod on my X40 too but it is not possible, the MAX3243 chip is located in the Ultrabase, not laptop itself.

http://www.porsche-foorum.org/album/alb ... _COM_1.jpg
http://www.porsche-foorum.org/album/alb ... _COM_2.jpg
http://www.porsche-foorum.org/album/alb ... _COM_3.jpg

[automobus]

Thanks for sharing!

I, too, wondered about replacing the monitor port. It looks like the cable runs through a very tight space around the Ultrabay cage.

[Raceboy]

It is still possible as the cable can be very thin, only three leads are needed (Rx, Tx and GND). I have used LCD cable wires for that before in other applications, works very well.

[lukee]

Very nice mod Raceboy! Do you think it is possible to cut off the LPT port in T4x series ThinkPad and put two USB ports instead?

[Raceboy]

It is but would require major surgery and you would lose rigity with the removal of LPT port because the magnesium frame is bolted to that. LPT port would need to be unsoldered and some sort of panel (out of plastic or metal) should be fabricated in order to mount USB connectors. And then you need PCMCIA-USB adapter and solder the wires there etc. Not worth it IMO, easier to use just the card itself.
I am not sure about soldering additional USB port wires directly to system board somewhere, digging in the schematic is needed.

[rumpelpudding]

Hi there! (Sorry for getting this old thread up again, but...)
Many thanks for the hints, i require a serialport and was wondering too if the serial-port shown in the OS could actually be used somehow. Thinkpad is a T40, pictures posted by raceboy above do fit my machine (even if its not a TR451). I do reply here because this thread actually helped me.

Unfortunately i do not own a dockingstation for the T40, so measuring the pins' layout to the COM-Port was not possible.
Therefore, if someone is attempting this, (and for the case the images go offline sometime):

The MAX3243 (RS232-Transceiver) in the T40 (+possibly others) to connect the RS232-Signals to is located under the internal Memory-Slot. The Keyboard and then the Memory-Module is to be removed to access it.
RS232-levelled Pins on the (28-Pin) MAX3243 are:
RXD: Pin 8 ,
TXD:Pin 11,
GND:Pin 25
(+optionally DTR:9, DSR:7, RTS:10, CTS:6, DCD:4, RING:5).

On the other (non232-) side the logic is 3.3V, in case anyone wants to interface directly. consult the datasheet for signal source/target-pins.

I just finished the wiring and it works great! As i am not that versed in soldering (lucky to get the two pins fixed...) a draw ground from somewhere else (metal-casing for dvd-drive) wich seems to be no problem. At least for the 'normal' baudrates (115k) and cable-length (about 1 meter or so) i tested.

Again, thanks a lot for the hints!
(and apologies for restating the above, but i thought as pure text it might be preserved in somewhat safer way)

Regards,
k