MP900c DIY serial cable

Have been looking for the serial cable for the 900c to use my GPS device and other older serialized equipment (no drivers needed). Have not found a source for the cable
atleast at a reasonable price

So I thought I would start a new thread here to see if a few can re-engineer one from the info we can put together.

It would be of great help if someone that has a serial cable that you can indulge us
with some info on the serial cable so that its less trial and error here.

If you have the serial cable what is needed is a map of the pinouts. How do you make a map of the pinouts you ask? well if you have a volt meter (continuity check) and the cable heres how to start.

Here is a standard DB9 cable


and the serial port of the 900c


The DB9 part of the cable is pretty straight forward (pins 1-9), the connector for the 900c is some type of flat connector (manufacturer ?) that has 9 fingers.

What is needed is to use the volt meter to see what pin from the DB9 side is connected to what pin on the 900c side.

Here is an example of pinout map (example only)


If we can get this info (pinout map) we can start to source parts and create a DIY
serial cable we all can enjoy.

hey... did you get my emails?

here is the info... copying from an email i sent to someone else.

thanks should go to cosmo0 and bsaunder...

so here is the copy.


(the additional pics that were attached in the email are uploaded here: http://hpcmonex.net/nec900/files/900serialpics.zip )


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about building the serial interface.

i don't know where to find the connector (or the serial cable
itself!), maybe the right mobile phone cable would work. but the
workaround is to solder the wires directly on the serial interface on
the 900c. this will of course permanently damage the outside of the
serial port but you can at least establish a serial connection now.

get the info from here: http://izemize.fw.hu/mp900_serial_cable_info.zip
this has pinout infos (and extra photos of the connector)!

that is all you need, but to help here is a quote from someone who did
this serial cable modification successfully:

> the crucial facts are :
> it is basically a 3 wire interface, rx,tx,gnd
> pin 3 on the mobo/serial connector goes to pin 3 of standard serial DB9 and
> pin 5 on the mobo/connector goes to pin 2 on standard DB9
> that's rx and tx taken care of
> then gnd:
> pin 5 of the DB9 connector is signal ground - connect it to ground point on mobo
so, what was done:
> where that annoying non-standard serial socket is on the mobo
> I lifted the nine pins from the mobo with a needle
> heated with soldering iron
> (hence ruined socket for further use
> then soldered fine 2 fine wires to rx and tx
> that's pads 3 and 5
> third wire goes to gnd on board
> I soldered to metal case of socket for gnd - easier to solder to

that's all,

i attached additional pics of the modification to help more!

someone else suggested soldering in a jornada 720 serial
connector..for that the cable is common enough
no one tried that yet though.

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....actually this mod ruins the socket but if you find the right connector then let us know!!

Thanks cmonex !!!
thats great to begin building the cable, you are a wealth of info.

I can use these pictures to try and source the connector for the 900c side
I'm sure theres something simular out there that can do the job or better the exact
part # so we dont have to tear up the case.

Wonder if anyone knows a contact at NEC that could help with parts? this could be useful for other projects as well.

Has anyone actually tried searching the official part number on google? I tried this and there tons of stores that had them but most of them were out but there were a few which I couldn't tell whether they had them or were out of them.
I went I think ten pages into it. If anyone else wants to try it here is the part number: OP-MP9-LINKSER

I did that same search, and I think its a waste of time.

Dont think these hits really have any serail cables (OP-MP9-LINKSER) they just want your time and info

It would be great if someone knows the part # for the serial end that goes into the 900c thats the part that needs
to be hunted down, dont think anyone has original serial cables for 900c anymore

I was trying to find the connector for the serial interface. The serial connector look like a mobile phone type of connector. I believe that if I can find the cable for the mobile that use the same connector, I can modify it as a serial cable. I search for mobile phone connector with 10 connectors. As I do not own the serial cable, I am not sure of the serial connector dimension.
I found a website that seem to be closed to the serial connector. The 3 connector from the top with 10 positions. Website link

Is this the correct connector?

Edited by nts 2007-05-07 10:14 AM

Its close but I dont think its the correct part. Dont know if you want to take the chance of trying them out?

I did some further looking and found the part is made by Honda of Japan (car part?)
Took apart a unit


Here is the other end of the serial cable (pics thanks to cmonex)


Notice that the numbers stamp on it
900c connector "A2 01Y"

and the serial cable side "A1 031"

just another piece of the puzzle right now but could help locate the correct connector.

I also did some looking and found the serial cable for the 700 and 800 MobilePros
Part # S1424-12S LINK HERE
NEC Data Synchronization
MC-RS4 Serial PC Cable Sync
Data Synchronization Cable for MobilePro 700 / 770 / 780 / 800

So the serial cable is different in the 900 as compared to the 800 models?
does anyone have a 900 cable they could plug into a 800 and tell us if its the same or not?

The 900 series serial cable will not even fit on the older MIPS machines...entirely different in size.

Thanks Rich for confirming that the cables are different, I knew this but wanted to be sure that I look under every stone to find the right cable.

It sure is funny though that the older MobilePros have plenty of cables to be had and the 900 series is gone?

Well, the older MPs' cable was a standard RS232C serial cable that worked in several other devices too, like the Casio H/PCs.

Reminds me of the serial socket of the 4000 series mobilons

Those are a bit smaller, though similar. (And of course they work in the Intermec 6651, which was designed by Sharp.)

Oic, I have a 900c on the way but never seen one in person...

I thought it look simiular though...

Gweb: yes it is strange that NEC changed the 900 cable. maybe it was intentional (block access to bootloader?). i realyl don't know..

same number A1 031 on my cable, btw. it would be a good idea to look in taiwan or japan?

ive got lots of hpc's btw and no sockets on them seem to be similar to this. i didnt check all of them though, i will try more later. the sharp isn't using this connector though.

oh, maybe the photos are misleading, because the sharp connector is MUCH bigger than this 900 one.



edit: more description : the actual metalish connector is well within the cable conenctor, the cable connector has several small teeth on one side, and on the other side it is even except for a little bump. if you look deep into the cable connector then you can see the metal (golden?) things deep in the end of the tunnel in it. i assume the 900 connects to those golden things and the outer cable connector is just making all it fit properly. hmmm i did it wrong, there is still metal at the side too.
sorry i suck at describing things,

i will try to take a photo of this soon.


oh more info, maybe it is obvious but the outer cable connector is the mirror of the serial connector in the 900 itself.

Edited by cmonex 2007-05-08 5:43 PM