Trackpoint Swap

[dz_alias]

Hello! I have an IBM KPD8923 and an IBM Model M13 (by Lexmark).

I love the Trackpoint IV of the KPD8923, but I hate that it's not mechanical.
I love the machanicalness of the M13, but I hate the Trackpoint II.

I have a spare KPD8923, of which I'm willing to donate the Trackpoint PCB, although the Trackpoint stick itself is broken.

I wanna do a swap, but I'm seeing potential issues...

1. The PS/2 plugs for each keyboard are different. The KPD8923 has 6 pins per plug, while the M13 has 4.
On further inspection, I found out that these are NC (no connect) pins. So I'm thinking that they're superfluous? Especially since the KPD only passes 4 wires to the PS/2 plug.

2. The Trackpoint II ribbon cable has 6 connects while the Trackpoint IV has 5 connects. I'd like to keep the TII stick in my M13 because the TIV in my KPD is brokeded. I'm hoping the biggest difference between the TIV and TII is how the data is processed at the PCB.
Does anyone know how the two sticks map out?
Electronically, is there output difference (if any exists) between the TII and TIV? If so, would I have to add / change resistors / capacitors to properly buffer the input?

I found a schematic for the TIV here, from this website. I'm looking for a schematic for the TII. If I find it, I still might need help.

3. The PS/2 Cable is fed 6 wires in the M13 as opposed to 8 in the KPD. I'm assuming four redundant wires were condensed into two. Ground and voltage supply I'm guessing? I'ma check it out with my multimeter, but if someone has a quick answer to save me from actually doing work, I'd appreciate it !

Thanks in advance for any help!

[Input Nirvana]

Interesting.

I would like to see pictures (if you can) of the M13 trackpoint pcb and stick.

I can't help you out specifically other than to offer as another option you can get a KPD8923 for about $20+ on ebay as a last resort if your swap idea can't work.

[kishy]

Interesting.

I would like to see pictures (if you can) of the M13 trackpoint pcb and stick.

I can't help you out specifically other than to offer as another option you can get a KPD8923 for about $20+ on ebay as a last resort if your swap idea can't work.

This isn't a nearly detailed enough breakdown, but if it's helpful, good.

The post in the "Kishy Owns an M5-2" thread where I also obtained and opened up my M13.

Note there are more attached files than embedded images...view all attachments.

Edit: I have more than this, I just can't find the post...hang tight.

[dz_alias]

Interesting.

I would like to see pictures (if you can) of the M13 trackpoint pcb and stick.

I can't help you out specifically other than to offer as another option you can get a KPD8923 for about $20+ on ebay as a last resort if your swap idea can't work.

The M13 Trackpoint PCB is also, incidentally, the keyboard PCB. I kinda need the keyboard to work too, so I'm not even going to touch it. The stick seems to be glued in, which is why I haven't been too excited about possibly having to remove it. If it REALLY comes down to it, I'll play with some resister values.

That's usually where I get my Trackpoint keyboards... although before I've gotten them from $30-$40. I saw just recently the thread on here about Trackpoint sources, I added the listing to my watched list .

This isn't a nearly detailed enough breakdown, but if it's helpful, good.

The post in the "Kishy Owns an M5-2" thread where I also obtained and opened up my M13.

Note there are more attached files than embedded images...view all attachments.

Edit: I have more than this, I just can't find the post...hang tight.

Thanks!

[dz_alias]

That M13 is in there tight.

I could see the glue just looking through the keys. I'd rather die .

I figured the output wires on the M13.

Yeller - Mouse Clock (CUT)
White - Keyboard Data (LEAVE ALONE)
Black - Shared Ground (UNSLEEVE)
Brown - Keyboard Clock (LEAVE ALONE)
Red - Shared 5V (UNSLEEVE)
Green - Mouse Data (CUT)

I figured I'd wire the TIV PCB out wires to the M13 out shared wires in parallel. And just take the original mouse clock / data wires and rewire them to the TIV PCB.

Good plan?

[Input Nirvana]

The M13 Trackpoint PCB is also, incidentally, the keyboard PCB.

DOH!

That's usually where I get my Trackpoint keyboards... although before I've gotten them from $30-$40. I saw just recently the thread on here about Trackpoint sources, I added the listing to my watched list .


Thanks!

Several here on GH bought more than one board from that ebay seller linked in that thread, and were able to get a more favorable price.

[dz_alias]

Several here on GH bought more than one board from that ebay seller linked in that thread, and were able to get a more favorable price.

I know.

What successful "Make an Offer"s have any of you had?

[Input Nirvana]

$20 shipping included for 6 boards, someone else had $20 + shipping for 3 boards. Shipping was cheap.

After you take out the Trackpoint, the board is perfectly fine. They are totally separate items.

[dz_alias]

$20 shipping included for 6 boards, someone else had $20 + shipping for 3 boards.

After you take out the Trackpoint, the board is perfectly fine. They are totally separate items.

For each board or total ?

Well not perfectly fine. There's the gaping hole between the GHB keys and possibly one below the spacebar if you remove the buttons too. I think I'm going to keep my trackpoint-departed KPD8923 for parts for my good KPD8923.

[Input Nirvana]

Sorry, per board.

I mean the keyboard works without the TP unit.

[dz_alias]

Sorry, per board.

I mean the keyboard works without the TP unit.

The M13 will, I hope. It'd suck some major ass if I went through the trouble of switching out parts and then it turns out the keyboard itself doesn't work.

[Input Nirvana]

Why not just ADD the independant TP unit?  (IBM KPD8923 TP IV above)

[kishy]

Yeah, M13 will do fine with TP removed, key is doing it without breaking the plastic plate underneath.

For the TP to be usable you'll need to have a controller for it, however, which is part of the M13 keyboard controller. M13 should be usable on a normal M controller with the same ribbon arrangement (some earlier ones had LEDs on a dedicated ribbon instead of integrated with one matrix ribbon).

[dz_alias]

Show Image

Why not just ADD the independant TP unit?

Please refer to posts #5 and #6 :).

Yeah, M13 will do fine with TP removed, key is doing it without breaking the plastic plate underneath.

For the TP to be usable you'll need to have a controller for it, however, which is part of the M13 keyboard controller. M13 should be usable on a normal M controller with the same ribbon arrangement (some earlier ones had LEDs on a dedicated ribbon instead of integrated with one matrix ribbon).

I'm using the KPD8923 controller, mainly because it *is* Trackpoint IV, and also since it's an isolated unit from the keyboard controller.

The whole premise behind this crazyness is I hate Trackpoint II, and want Trackpoint IV in my mechanical board.

[kishy]

Oh right.

Continuity is something not typically found in geekhack threads lol.

Using the TP controller of the M13 for the newer TP presents problems. The biggest obvious one is that the IV should have tap-to-click functionality but the II does not, so you'll lose that if it even works at all on the II controller.

[Input Nirvana]

Please refer to posts #5 and #6 .

Got it. Of course. Pics are worth 2 thousand words when it's past bedtime. What a hassle....I'm in similar spot with my silly keyboard issues too. You aren't alone.

[Input Nirvana]

TP IV has tap to click? You mean on the pointing stick portion? Mine don't

[kishy]

That might be III, and IV was the one where they removed it...

Gotta read me some Wikipedias.

[dz_alias]

TP IV has tap to click? You mean on the pointing stick portion? Mine don't

Neither does mine, which is the way I prefer it. I don't want my mouse jumping around every time I go to click something .

Continuity is something not typically found in geekhack threads lol.

Sweetness. I'll fit in.

EDIT: Found some info here.

I really hope the negative intertia is at the controller level, as opposed to stick. I do remember on the KPD8923 PCB that "-V" was one of the input lines...

[dz_alias]

I need a Trackpoint II schem! I haven't been able to find one.

I tried creating an account at IBM's website so I could ask for one, but I'm unable to sign in. I'm sure someone here has an account there, right?

Or maybe a TII schem floating around?

[dz_alias]

Wouldn't be much of a schematic.

Strain gauge goes out to ribbon cable.

Show Image

Not much of a schematic, no, but one nonetheless.

The ribbon's mostly obscured. I need a "pinout" for the ribbon leads, so I know if the TII stick and TIV controller are compatible.

I could do it with trial and error, but that's tedious and I'm going to be as lazy as I possibly can. I'm sure one of the IBM freaks out there has something that could be of help...

[ricercar]

I need a "pinout" for the ribbon leads, so I know if the TII stick and TIV controller are compatible.

Hey Input Nirvana
What vintage TrackPoints are on our donor keyboards?

Thank my daughter for busting my TrackPoint yesterday. This is the top of the PCB, with the TrackPoint "up" arranged at the top of this photo. There are no traces on the bottom of the PCB. Unfortunately I don't know which of the two small pads is common.

[dz_alias]

Hey Input Nirvana
What vintage TrackPoints are on our donor keyboards?

Thank my daughter for busting my TrackPoint yesterday. This is the top of the PCB, with the TrackPoint "up" arranged at the top of this photo. There are no traces on the bottom of the PCB. Unfortunately I don't know which of the two small pads is common.

Show Image

I dunno that you'll be able to fix it.

The tolerance is so low that even if it registers movement, it's going to be diminished and subject to a lot of noise.

I tried to fix one and it didn't work the slightest. When replacing the stick, it's only viable to replace the PCB it's attached to as well with a whole unit. At least in my experience with it.

[Input Nirvana]

I think they are TP IV. Is thtat your question? I don't have confirmation of that, but have seen several references to that effect. I should, and probably will look into that late this week or next weekend.

I had to grab another multimeter the other day since my Fluke 77 managed to vanish without a trace  Not many things less satisfying than replacing a solid item with a $15 less-than-solid  item. Can I tell you which one is common with a multimeter?

[dz_alias]

Lol someone give me pinout naow or I'll hissy fit.

Tried emailing IBM... but I got confused and was easily deterred. I think that's how they filter out a lot of customer support.

[dz_alias]

Update: I'm going to run the ribbon cables to their respective places, solder wires to them, run the wires outside the keyboard, and attempt to mix and match them until I get the trackpoint working. Seriously. That's what I'm going to do. I've no choice, I can't find a Trackpoint II schematic fuggin' anywhere.

[EverythingIBM]

Lol someone give me pinout naow or I'll hissy fit.

Tried emailing IBM... but I got confused and was easily deterred. I think that's how they filter out a lot of customer support.

I've emailed IBM many times, they never respond.

EDIT:

The best place for support is to make an IBM account and go on their support forum.

[Input Nirvana]

You can't do that with a voltage tester? I mean to save all that work?

[dz_alias]

You can't do that with a voltage tester? I mean to save all that work?

Trackpoints work as variable resistors right?

It'd be just as much work. One'd be observing the change in current in my multimeter and the other the change in mouse position on my screen.

I'd like to do the latter because I know not only am I making a proper connection; but which axis as well.

[Input Nirvana]

Right, and the axis issue would not be resolved with a tester....
Gotta work on thinking BEFORE talking...

Understood.

[NamelessPFG]

I've been thinking about TrackPoints lately...but for a different reason.

The ministick in my Thrustmaster HOTAS Cougar throttle is acting up now. Must be the cheap pots. The real F-16 apparently has something less gamepad analog stick-ish and more TrackPoint-ish with click-down functionality. Why not get it even closer to the real deal without spending a fortune on an actual F-16 throttle?

Alas, while there may be such mods to have a force-sensing flight stick (one of which was already installed by the prior owner and is based on an out-of-production CTS TrackPoint-esque sensor, the sort without apparent strain gages), there are none for the ministick. Guess I'd have to develop my own...except that I have no idea as to what sensor I'd use, mostly because I don't want to lose the push-down functionality. It also has to act as a voltage divider on both axes, not a resistor.

[dz_alias]

Mother of bump!

Dragged out my M13 today. It's been in a drawer since I've moved.

Wired it up, to make sure it's fine. All the keys work (typing on it now), and the left and right mouse button works too.

I started testing with trial-by-error, and I'm figuring it out. I know one working combination is V4,G6,Y5, which has the trackpoint working on the Y-axis. I tried the rest of the pins with the X cable but no dice on the X-axis.

I'm going to restart tomorrow because this is what I've been doing:

Code: [Select]

for (g=1,g<6,g++)
{
    for (v=1,v<6,v++)
    {
        if (v==g) {continue;}
        for (y=1,y<6,y++)
        {
            if (y==v || y==g) {continue;}
            check_****(g,v,y);
        }
    }
}

I was testing every possible combination, with two results. Erratic cursor behavior, or no cursor movement. I assumed that no cursor movement meant that it was a possibly correct combo, and that erratic cursor movement meant that it wasn't a possibly correct combo.

Of course at the very end I found out this isn't so.

Part of the trackpoint hardware acts as a variable noise gate. If you give it enough time (i.e. a few seconds), the cursor will slow down and eventually stop moving. It's at this point you can move the trackpoint itself and see if has any effect.

The first time I noticed this was at V6G4Y5, but the axis was upside down so I switched G and V. I'm assuming G is ground and V is voltage, or something.

Anyway, the whole fuggin point of me posting this is, after my rigorous extensive highly scientific testing, I broke a couple prongs on the ribbon cable connector for the trackpoint.

So how the hell am I supposed to connect the ribbon cable to the wires for testing?

I have a soldering iron, but it's too big and I'd likely short out the traces.

[Input Nirvana]

I'm looking at mine...that looks crazy tough. Is it possible to get another ribbon cable? I'm not very familiar with PARTS. but it seems like you can buy almost anything...

[dz_alias]

I'm looking at mine...that looks crazy tough. Is it possible to get another ribbon cable? I'm not very familiar with PARTS. but it seems like you can buy almost anything...

I'm not sure. I've never modified electronics in this fashion before. The ribbon cable itself is attached to the permanently fixed trackpoint, so I can't remove it or alter it. The connector was desoldered from the circuit board, but the legs broke off in testing, so I need another way of attaching the ribbon cable to the new controller. I can't solder the wires directly onto the ribbon, because I'm still testing, I don't have the ability to do so without shorting out the "pins", and it might not even work to begin with.

[Input Nirvana]

Is that "solder glue" an option? I haven't used it and not really familiar other than what I'm sharing with you...but I believe it's a highly conductive glue that you can use in limited situations...

[dz_alias]

Is that "solder glue" an option? I haven't used it and not really familiar other than what I'm sharing with you...but I believe it's a highly conductive glue that you can use in limited situations...

Sounds too messy, considering I'm going to need to swap wires several times over. Give me just a second.

EDIT: There's exactly 120 possibly configurations using the minimum of three wires. I have alligator clips, but they're too big and would be tedious to use on the ribbon itself.

EDIT2:

SELLING: IBM KPD8923 (black)

How much?

[Input Nirvana]

I paid $45 and $6 shipping. I'll sell for $45 plus shipping and send the cheapest method we can find. Where are you?

I have one other idea:
Create an "intermediate connector". It will match the ribbon on one end, and "flare out" at the other end so you can attach alligator clips. As far as matching the ribbon on one side, it would more or less be a "touch contact".  Does that sound like something that would work?

[dz_alias]

I paid $45 and $6 shipping. I'll sell for $45 plus shipping and send the cheapest method we can find. Where are you?

Too much, I'm poor. I'd rather wait and get some in bulk.

I have one other idea:
Create an "intermediate connector". It will match the ribbon on one end, and "flare out" at the other end so you can attach alligator clips. As far as matching the ribbon on one side, it would more or less be a "touch contact".  Does that sound like something that would work?

I have no idea. How would I construct something like that?

[Input Nirvana]

Yea, it's almost new. I think the black board is more for using as a complete unit, rather than strip for the Trackpoint. The KPD8923 are very nice boards (for rubber domes). I am looking to get a Lenovo board that has a USB trackpoint, that will give me 2 PS/2 trackpoints from $20 KPD8923's. But I won't know for certain until April

I'll have to maybe draw it out for you, I think it would work fine for testing. I'm traveling and can do that tomorrow.

[dz_alias]

Yea, it's almost new. I think the black board is more for using as a complete unit, rather than strip for the Trackpoint. The KPD8923 are very nice boards (for rubber domes). I am looking to get a Lenovo board that has a USB trackpoint, that will give me 2 PS/2 trackpoints from $20 KPD8923's. But I won't know for certain until April

I'll have to maybe draw it out for you, I think it would work fine for testing. I'm traveling and can do that tomorrow.

I have one KPD8923 already, which I love. Until I get the M13 set up, it's my favorite.

I'd appreciate that! Thanks so far!