Model F BigFoot faulty board.

[Jaki1122]

Hello everyone, first and foremost, thanks for your time. I've got this lovely Model F BigFoot that I bought cheap (2nd hand of course) and I trying to make it work. I've restored a Model F XT in the past and succesfully made a Soarer's Coverter out of a ProMicro. This time though... no such luck.

Before you say anything, yes, I know, using the ProMicro for the BigFoot requieres soldering a cable directly to the pad of the resistor for the on board LED as that is also used as a pin, done so, loaded the appropiate code for it made sure I've conected everything correctly.... but many keys aren't recognized, while others activate 3 or 4 keys. Eventually I decided that either the board is fried or that I'm an idiot (which is quite realistic if you ask) and done something wrong so I gave in and bought an actual Teensy for simplifying things, not really expecting it to work fine but you know... there's always hope. Guess what, same result. I've checked the ground screw of the backplate, no rust, tight, just a few ohm resistance between the backplate and GND on the Teensy.

Now obviously the board is doing stuff, it does output characters when you press keys, so it is not fully dead, just suffering an agonizing terrible pain every time it tries to work. I'm aware this boards are a bit delicated as every other Buckling Spring Capacitative board, but still, any change of repair of do I have to find an alternative solution. I've read somewhere long time ago there's a board that is a sort of drop in replacement (chop the old one, solder the traces to the new one). What do you guys think?

Thanks for your time!

[Muirium]

Delicate? I’d rate (my beloved) Model Fs as hardy tanks among keyboards! They aren’t as flaky as your trigger word implies.

Tries to calm down.

You ever been inside an F? I’d suggest taking a peek inside this board to check for flaky foam and general condition. It’s a relatively simple procedure (and well worth learning) versus the destructive nightmare getting into the guts of a Model M.

You’re right that the fact some keys are showing up means your converter and controller are live, at least. The problem sounds analog to me.

[Jaki1122]

Delicate? I’d rate (my beloved) Model Fs as hardy tanks among keyboards! They aren’t as flaky as your trigger word implies.

Tries to calm down.

You ever been inside an F? I’d suggest taking a peek inside this board to check for flaky foam and general condition. It’s a relatively simple procedure (and well worth learning) versus the destructive nightmare getting into the guts of a Model M.

You’re right that the fact some keys are showing up means your converter and controller are live, at least. The problem sounds analog to me.

Indeed I've been inside a Model F... twice. I did a full restoration on the XT, even painted mounting plate. Some time later I had to open it again to do a minor repair. This BigFoot on the other hand does look quite fine, yes the foam is long gone, other than that no rust, paint looks nice. I'm not sure this is what is causing the problem, aproximately 50% of the keys won't register, while the other 50 will trigger 2 or 3 keys when pressed. Important to mention, it is consistent in its behaviour, meaning, the "v" key will always trigger "v" "," and " " no matter how many times you press it or how you do so.

Still I can open it and replace the foam and maybe repaint the mounting plate. I've seen somewhere someone painted the plate in bright red and it was gorgeous, but I'm not sure if I'd be a sort of monster for changing the original color. Still it was so pretty in red...

[jsheradin]

Triggering multiple adjacent keys sounds an awful lot like matrix shorts. Being cap-sense I'm sure there's some weird grounding and self adjust algorithms that might cause the same effect. It definitely wouldn't hurt to give the plates and PCB a good cleaning. Visually check for any corrosion, broken traces, rubbed through insulation, etc.

Worst case I think you can drop in a normal XT PCB and use a much simpler converter. Definitely avoid chopping up the original PCB if you can. Someone in the future might want to reverse the mods and use it with an original system. If the original plates are not corroded I'd also leave them as-is, just give them a good cleaning.

[Jaki1122]

Here's a coupble of pictures of how it looks as of now. I'll take it apart, give it a good clean, new foam and then I'll put it back together and try again.

[Jaki1122]

Well... already open. I doesn't look half bad. Not much dirt to speak of (haven't done any cleaning when I took the pictures), foam is degraded but not as much as I thought. Anyway, I'll clean it up, new foam... I'll let you know how it goes.
Still debating if I should repaint the mounting plate. Looks ok, not perfect. I'll se what I do.

[vyquad]

Provided the controller is actually dead and not just wired wrong etc, you can cut the traces to the controller and solder an xwhatsit

[Muirium]

Aye, everything looks okay. I’d be tempted to upgrade to an Xwhatsit controller, but you’ve a daunting bit of chopping to do first: either all those little traces or the PCB itself! Before you get destructive, does anyone know if this type of board (and therefore IBM controller) is known to work correctly with Soarer’s converter? IBM made a lot of stuff. It could be that nothing is broken, just not fully supported.

What protocol / code set does Soarer’s converter say it’s using? A paste of the output from scinfo could be informative.

I’d try QMK’s XT converter firmware on the Teensy first and take a look at its output in QMK Toolbox to see if it’s the same there. Probably will be the same misbehaviour, but it’s always good to try low risk options first.

[hellothere]

You might want to check out https://geekhack.org/index.php?topic=48950.0, especially the posts that mention using the jumper pins.

I would like to know what the model number of the keyboard. In the Geekhack thread, there's "EC998852" labeled on the PCB. I'm pretty sure that's the same number that was on the 3 XTs I've sold. The one on yours, however, is "EC528372." I don't know if that makes a difference for anything.

If you're using a Pro Micro clone, spend the extra to buy a real one. I've had a lot of issues in the past couple months with the clones in the past couple months. However, I'm going to try one of these.

[pandrew]

• Soarer's:
  As far as I know, bigfoot doesn't have a full 'controller' that would convert to a serial port. Instead it only has the analog circuitry, that you have to drive with a parallel bus. So it will not work with Soarer's Converter, but it will work with Soarer's Controller, which is different.
  Did you try to follow this thread?
• QMK:
  On another note I googled a little more and I found that at some point QMK also had ibm_5291 support
  It was removed with this commit at which point it was broken.
  
  If you want to try QMK your best bet is to try to go back to an older version when it still worked,
  I think either listofoption's original commit, or noroadsleft's commit that specifically tries to improve this keyboard.
  Also you might try pinging listofoptions, maybe he can help.
• Xwhatsit:
  Chopping/trace-cutting/almost-all?-component-desoldering, and attaching an xwhatsit is possible, but quite a drastic change to your keyboard, so I would try to make sure first that there's no way you can get the original circuitry working. If you need to go the chopping route, some important information:
  1. You must use and xwhatsit Beamspring type controller. Either original xwhatsit 5251 beamspring controller, or my compact beamspring controller, or the TH Xwhatsit controller, or DMA's common sense.
     F-type-only controllers will not work, because they don't have enough columns. Also displaywriter controllers will not work.
  2. If you chop or cut traces, make sure you chop/cut in a position where you can still solder wires to all rows/columns/grounds
  3. If using my firmware with one of the specific beamspring xwhatsits, only one specific wiring will work correctly, so please ping me to double-check.
• As an interesting side note FXT Type 1 keyboards have a bigfoot-equivalent sense PCB, but they also have a little daughter PCB in the corner that actually has the rest of the controller, so they can output AT protocol. See here for some pictures.

[Jaki1122]

Aye, everything looks okay. I’d be tempted to upgrade to an Xwhatsit controller, but you’ve a daunting bit of chopping to do first: either all those little traces or the PCB itself! Before you get destructive, does anyone know if this type of board (and therefore IBM controller) is known to work correctly with Soarer’s converter? IBM made a lot of stuff. It could be that nothing is broken, just not fully supported.

What protocol / code set does Soarer’s converter say it’s using? A paste of the output from scinfo could be informative.

I’d try QMK’s XT converter firmware on the Teensy first and take a look at its output in QMK Toolbox to see if it’s the same there. Probably will be the same misbehaviour, but it’s always good to try low risk options first.

Well, I'd very much like avoiding chopping anything off, just for the sake of conservation, or in any case, do the absolute minimum destruction.

I'm following this guide: https://geekhack.org/index.php?topic=48950.0
I should point out, my Bigfoot is Spanish, keycaps have Spanish labeling and everything but I doubt there's difference big enough to cause the behavior I'm having. Electrically should be the same as the English version, just the layout is different.

[Jaki1122]

You might want to check out https://geekhack.org/index.php?topic=48950.0, especially the posts that mention using the jumper pins.

I would like to know what the model number of the keyboard. In the Geekhack thread, there's "EC998852" labeled on the PCB. I'm pretty sure that's the same number that was on the 3 XTs I've sold. The one on yours, however, is "EC528372." I don't know if that makes a difference for anything.

If you're using a Pro Micro clone, spend the extra to buy a real one. I've had a lot of issues in the past couple months with the clones in the past couple months. However, I'm going to try one of these.

The guide you mentioned is the one I'm primarily using. About the boards, yes 1st try was on a cheap, ProMicro Aliexpress clone, but ever since I've upgraded to an actual Teensy, just as the guide states (done so to take possible problems out of the equation). I've checked the jumper cables ande the board jumpers, they are as indicated.
And about trouble with clone ProMicros... Have one that does every except sending anything over serial Tx. Boy that was some fun troubleshooting, back then when I was younge and naive...

[Jaki1122]

• Soarer's:
  As far as I know, bigfoot doesn't have a full 'controller' that would convert to a serial port. Instead it only has the analog circuitry, that you have to drive with a parallel bus. So it will not work with Soarer's Converter, but it will work with Soarer's Controller, which is different.
  Did you try to follow this thread?
• QMK:
  On another note I googled a little more and I found that at some point QMK also had ibm_5291 support
  It was removed with this commit at which point it was broken.
  
  If you want to try QMK your best bet is to try to go back to an older version when it still worked,
  I think either listofoption's original commit, or noroadsleft's commit that specifically tries to improve this keyboard.
  Also you might try pinging listofoptions, maybe he can help.
• Xwhatsit:
  Chopping/trace-cutting/almost-all?-component-desoldering, and attaching an xwhatsit is possible, but quite a drastic change to your keyboard, so I would try to make sure first that there's no way you can get the original circuitry working. If you need to go the chopping route, some important information:
  1. You must use and xwhatsit Beamspring type controller. Either original xwhatsit 5251 beamspring controller, or my compact beamspring controller, or the TH Xwhatsit controller, or DMA's common sense.
     F-type-only controllers will not work, because they don't have enough columns. Also displaywriter controllers will not work.
  2. If you chop or cut traces, make sure you chop/cut in a position where you can still solder wires to all rows/columns/grounds
  3. If using my firmware with one of the specific beamspring xwhatsits, only one specific wiring will work correctly, so please ping me to double-check.
• As an interesting side note FXT Type 1 keyboards have a bigfoot-equivalent sense PCB, but they also have a little daughter PCB in the corner that actually has the rest of the controller, so they can output AT protocol. See here for some pictures.

That's lots of information, thanks! I've mistakenly said that I made a Soarers converter in the original post but you are right, is not the converter but the controller. However I did follow the guide you and others mention.

Maybe the fact that mine is Spanish and not English would affect the keymap but I don't think that's it. It would type 3 characters on some keys and none in others. I think it may be a hardware issue, either not registering correctly or the controller is cooked. I hope I'm wrong and it's just that the soarers controller is no good for this specific keyboard or a bone head mistake (I'm very proficient with those), but I don't know.

[Jaki1122]

Tomorrow, if the weather allows, I'll pick some new foam and put everything back together. Then I'll start checking (again) at the jumpers, the controller and all that.

Thank you so much for your help so far, I'll keep you posted.

[orihalcon]

I haven't converted one myself, but I always thought the easiest route would be to use an FXT capsense pcb instead which is easier to convert.

[hellothere]

I haven't converted one myself, but I always thought the easiest route would be to use an FXT capsense pcb instead which is easier to convert.

If the person that has sold a bazillion Soarer's converters for many different configurations makes a suggestion, it's probably good to listen

(So, orihalcon, I'm getting 50% off that next controller, right?)

[hellothere]

There's also https://sharktastica.co.uk/topics/kb_connections#529X. Goes with http://www.kbdbabel.org/conn/kbd_connec ... 5291-2.png.