IBM model F: Suspected dead PCB?

mcasomm

29 Dec 2021, 23:12

Hello, first post on this forum

I recently got an IBM model F. After 2 months of use, it suddenly started spouting random characters whenever I connected it, which obviously made it impossible to use. I opened it and saw the foam was more degraded than I thought (it was literally falling to dust), so I disassembled it to overhaul it. For context, I soldered up a soarer's with an micro-USB arduino pro micro.

I've resoldered the connections and plugged the bare PCB for a test, and to my surprise no key press registered. The PCB was bare, but I also tried it with the brass plate attached and the grounding screw secured tightly. I've also tried:

-Pressing with fingers with and without brass plate
-Pressing with the switch with and without brass plate
-Installing a working switch assembly with barrel plate, without foam. The switch actuated and buckled normally, no response
-Sodering with another arduino pro micro (USB-C model)
-Sodering the wires directly onto the PCB
-Using hid_listen to see the converter's response
-> At best I got some r05 and r06 errors, at worsta string of random "r" errors I haven't been able to replicate


At this point I think I've tried everything possible and concluded the converter is not at fault and that the PCB is dead, and I thought I'd ask here just be sure there's nothing else I can do. In that case, what would be my best bet to get a new PCB?


Thanks

User avatar
Muirium
µ

30 Dec 2021, 00:57

Which Model F? Not an XT, hopefully.

My AT never much liked running from a pro micro. Took too much power I think. Sometimes it would work a bit, but never for long. In my case I knew the controller was fine because it still worked with my own external Soarer box: which ran from a Teensy. But I wound up swapping out the controller entirely for an Xwhatsit. That board now runs QMK with Pandrew’s auto calibration.

I hear DMA’s controller is also good. Never tried it myself.

mcasomm

30 Dec 2021, 01:19

Unfortunately for you it is an XT! I'm pretty sure the controller is not at fault, it worked fine for hours on end on the pro micro and I also tried bridging the 5V jumper - no effect.

At this point I'm thinking about saying "screw it" and repurposing my keys on a repro

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jsheradin

30 Dec 2021, 02:28

Did you double check the wiring? I've seen the same r05/6 strings before when DATA and CLOCK were swapped.

With particularly cheap pro micro clones I've had them randomly fail with no apparent cause. I have one that is absolutely fine by every measure (Arduino digitalRead/write/PWM/analogIn/etc) but refuses to talk to a board when running Soarer's. Worth changing it out if you have another on hand.

mcasomm

30 Dec 2021, 05:27

I did change out the micro and double checked the wiring. Even tried swapping clock and data incase I got them wrong, no change. I'll try ordering another pro micro but that'll take weeks at best from ali

User avatar
Muirium
µ

30 Dec 2021, 09:30

Dude, you’re getting a Teensy. ;) I’ve used a dozen of them over the years and never had any kind of issue.

The XT is bad news simply because you have no replacement controller options. AT, F122 and Kishsaver all have modular controllers which are simple to swap out for something modern.

The good news is it’s very unlikely your controller is the problem. I’d go for a real Teensy instead of playing slow roulette with a series of pro micros only to find one that works for a few days then …

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jsheradin

30 Dec 2021, 16:21

Teensys are the way to go for a nice board; I've had much better luck with them personally. Their halfkay bootloader seems to play better with QMK as well.

If the board still doesn't work and there's nothing obviously wrong with the PCB (corrosion, etc.) I'd go for a full controller swap. You can use an xwhatsit controller on an XT but you need to desolder all the components from the board. I've seen a few done before.

User avatar
Sheepless

30 Dec 2021, 16:37

Might be worth stocking up on Teensys. PJRC say "PJRC has sufficient inventory to keep Teensy 2.0 available until at least March 2022, assuming sales continue at the 2019-2021 rate. We do expect to discontinue Teensy 2.0 in 2022". They're so expensive compared to Pro Micros, though.

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jsheradin

30 Dec 2021, 17:00

Sheepless wrote:
30 Dec 2021, 16:37
Might be worth stocking up on Teensys. PJRC say "PJRC has sufficient inventory to keep Teensy 2.0 available until at least March 2022, assuming sales continue at the 2019-2021 rate. We do expect to discontinue Teensy 2.0 in 2022". They're so expensive compared to Pro Micros, though.
They are pretty pricey but I don't know of another 32u4 dev board that exposes as many pins for the size.

Crazy to me that PJRC would want to discontinue the 2.0 though. I would have guessed it's their best selling board. Everything new they make is 5V intolerant so they're useless for many hobbyist projects.

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Muirium
µ

30 Dec 2021, 19:46

They’ve been trying to “sunset” them for a while. Years actually. I suspect it’s to try to move people (and especially the projects) onto their 32 bit Arm stuff. But what use is that to us? Tough noogies!

Now: would I put it past them to kill Teensy 2 at last? No, especially now in the age of (global facepalm) chip shortages. So you may want to stock up indeed. I just suspect PJRC will find a lot of its sales dry up the day they cook the golden 8 bit goose.

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fohat
Elder Messenger

30 Dec 2021, 23:58

Muirium wrote:
30 Dec 2021, 09:30

I’ve used a dozen of them over the years and never had any kind of issue.
I second this emotion. I never even tried to go cheap because the saving was just a few dollars and Teensy 2.0 was always a sure thing.

They were even cheerful about giving me a replacement once in a situation where I later realized that it was almost certainly my fault.

User avatar
DMA

31 Dec 2021, 18:23

Muirium wrote:
30 Dec 2021, 09:30
The XT is bad news simply because you have no replacement controller options. AT, F122 and Kishsaver all have modular controllers which are simple to swap out for something modern.
Actually, XT's controller part is connected to "sense card" part by a row of "jumpers" each made out of two vias with a track joining them. Just cut those tracks and solder any modern controller to the "sense card" part using sense-card side vias for the holes. These vias are large enough for your average wire (26AWG?)

User avatar
DMA

31 Dec 2021, 18:27

Muirium wrote:
30 Dec 2021, 19:46
I suspect it’s to try to move people (and especially the projects) onto their 32 bit Arm stuff. But what use is that to us?
Paying less money for it, I guess? Those atmegas are produced by a company that was bought by a competitor like 5 years ago (Atmel is dead, baby. Atmel is dead.). Don't get me wrong, atmega needs to go: harward architecture SUCKS. ARM is way easier to program for.

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Muirium
µ

31 Dec 2021, 20:02

Sure. But for every one person who programs a converter, like yourself, there’s twenty thousand or more, like me, who’d never dream of it. All the converter software is on Teensy 2. So we stay loyal, until Soarer is ported.

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DMA

01 Jan 2022, 07:48

Muirium wrote:
31 Dec 2021, 20:02
Sure. But for every one person who programs a converter, like yourself, there’s twenty thousand or more, like me, who’d never dream of it. All the converter software is on Teensy 2. So we stay loyal, until Soarer is ported.
Yeah, non-opensource software sucks. Not sure what's to port there though. What's special about Soarer that's not in QMK in 2021?

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zrrion

01 Jan 2022, 08:38

The only real thing soarer has going for it is the remapping, which is drag and drop with a text file, whereas QMK needs to be recompiled and reflashed. If something comes with via/vial that's a moot point though since that's even easier for a layman to remap.

User avatar
DMA

01 Jan 2022, 08:42

so, AT -> USB with a GUI will obviate Soarer converter?

Too bad I don't have any AT keyboards on hand. Adding support for that to CS will be like 4 hours of wall clock time.

User avatar
zrrion

01 Jan 2022, 09:04

I mean, a lot of folks won't switch from what they're used to until it no longer works on their OS, can't do anything that would change their minds on the matter. The real thing that'll get people to switch is putting a one-size-fits-all converter onto an orihalcon converter. Lots of people have those and while you can reflash them it is risky. They don't have any way to enter boot mode from the converter itself, you need to enter boot mode by assigning a key on the keyboard to boot mode. On soarers that's not an issue since boot mode doesn't have anything to do with changing the key map. with QMK though you would have to make sure that every keymap you flash to it had some way to enter boot mode. If you forgot to include that you have a converter that can't ever be updated.

so an xt/at > usb converter that can be remapped without entering boot mode and has a gui to manage remapping would entirely outmode soarers converter if it was open source.

Ideally the GUI would be able to load soarers keymaps as well so that transitioning is super easy. Then there's really no reason not to switch. The source is open, you can't lock yourself out of your orihalcon converter, and you can hit the ground running by loading your new converter with your old keymaps

User avatar
DMA

01 Jan 2022, 09:14

Probably nobody ever will support soarer keymap files though. They have IF statements, it's almost like you can write generic programs in that language.

But I agree with you that requiring to reflash to change keymapping is super retarded and was a chief reason I ended up writing my own firmware.

User avatar
zrrion

01 Jan 2022, 09:37

full support might not be needed, but simple keymaps that set up a few layers would be greatly helpful

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Muirium
µ

01 Jan 2022, 11:29

A few things that make Soarer's magic, ranked by most important first:
  • Good defaults. You want to just plug in a board and find it all essentially just works as intended. No configuration necessary.
  • Simple remaps. The main Soarer feature in practice is simply moving keys around. Make this is as easy as possible.
  • Simple layers. Layers are immensely powerful and not always necessary. But they really do help raise compact vintage boards to another level.
  • Simple macros and sets. These are Soarer's most advanced features, and I loved them when I relied on them. Not essential, however. Well, not usually. But sometimes they're exactly what you need!
  • Applying all of these based on the recognised keyboard. This one is what made my Soarer box so adaptable. Many keyboards share the same ID, however, (curse you AB84!) so I also used sets to manually apply these with a keystroke.
Honestly, that first one is so important, you could just do that for AT alone and have an 80% replacement for Soarer's converter. The remaining 20% is where 80% of the effort lies, however, so you are warned! :lol:

I'd love just that first point in a single firmware that supports AT and ADB. Extra bonus points for NeXT! TMK can handle all of them, and I love it in my HHKB, but I find it unwieldy for converters. Soarer's just so solid at that "simple" yet demanding job.

I'm less demanding for the fancy second and third order features now that I use Karabiner for my insane fiddling. In fact, here's a request to make that easier, if you do try this:
  • User definable USB ID. So I can tell Karabiner to look out for a given converter (and therefore keyboard) to apply layout-specific rules selectively on the host.

mcasomm

14 Jan 2022, 02:03

What's the pinout from the Teensy to the keyboard? For some reason I can't find any reference online, only posts concerning the pro micro

mcasomm

14 Jan 2022, 02:25

GUYS! CANT BELIEVE IT, IT WAS THE PRO MICRO! PLUGGED IN A TEENSY AND IT WORKS FINE!

I was this close to cutting the board and buying a Xwhatsit, thank you so much Muirium. In the process I did order a xwhatsit and another model F from China (got it pretty cheap off the used taobao). Guess I'll have more for future projects.

mcasomm

14 Jan 2022, 02:36

Here's a picture of the keyboard now - As soon as I get a mini-micro adapter it'll be back in the shell
Image

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Bjerrk

14 Jan 2022, 09:15

Damn! Congratulations, dude!

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Muirium
µ

14 Jan 2022, 11:15

mcasomm wrote:
14 Jan 2022, 02:25
thank you so much Muirium.
You’re welcome. 8-)

Filing this one in the Pro Micro file, for the next time someone asks. They’re good most of the time, but flaky. Bitten me before, too.

__red__

22 Mar 2022, 21:06

I just had someone on a discord channel tell me that I was overpaying by buying a teensy.

Nah, I'm only using a few of them - I can afford the extra $$ for the convenience and reliability. My time is worth it.

Now, if I were building a few hundred of them…

(nah, who am I kidding. If I was buying a few hundred of them i'd build a custom PCB)

User avatar
DMA

23 Mar 2022, 00:12

__red__ wrote:
22 Mar 2022, 21:06
(nah, who am I kidding. If I was buying a few hundred of them i'd build a custom PCB)
Wait, you don't have a stepper in your basement?

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fohat
Elder Messenger

23 Mar 2022, 01:26

__red__ wrote:
22 Mar 2022, 21:06

overpaying by buying a teensy.

convenience and reliability.
I have always used Teensy gear. Granted I have only built half a dozen converters (mostly for Model Fs) but I will spend a sawbuck for convenience and reliability.

__red__

25 Mar 2022, 03:20

DMA wrote:
23 Mar 2022, 00:12
Wait, you don't have a stepper in your basement?
I do have a pick and place machine :)

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