IBM F XT Spewing

Athen

27 Jul 2020, 13:37

Hi peeps, sorry to post another IBM F XT problem post, but after scouring the forums on both GT and here, as well as reading though the Soarer's converter documents, I can't seem to fix my problem.
The absolute vomit of keys.
The absolute vomit of keys.
IMG_20200727_213430.jpg (2.5 MiB) Viewed 1064 times
Currently, I have built a teensy 2.0 Soarer's converter, first without the pull-up resistors, and now with resistors, and both still have the same problem, though the latter did work for an hour, before deciding to spew scan codes. I have tightened everything that should connect to ground, but that seems to have been futile. The nut inside the keeb has also been tightened as much as I can, and has been re-tinned. The keyboard seems to work on very rare and fleeting occasions for about 4 key presses before deciding to go off on its own.

Here's my converter:
IMG_20200727_213401.jpg
IMG_20200727_213401.jpg (3.44 MiB) Viewed 1064 times
IMG_20200727_213418.jpg
IMG_20200727_213418.jpg (3.43 MiB) Viewed 1064 times

Please disregard the GND at the bottom, I couldn't remove the small piece of wire from my previous attempt.
I'm worried about the original cable, as the ground connector seems to be very thin and frayed, though I have no idea on how to fix this without damaging too much. I have not tried an in-case converter, so that might fix it, but I like the external look of the cable.
This is most likely the cause of the problems.
This is most likely the cause of the problems.
IMG_20200727_214039.jpg (2.51 MiB) Viewed 1057 times
I would purchase an orihalcon converter, but it is absurdly expensive for me right now, as shipping is over $60. So making one was way cheaper.

I am at a loss, so any ideas or solutions will help a bunch. It really blows that this is my first post, but oh well.

Update: funny this, upon closing the keyboard, the ground connector snapped off- so now I also need help with repairing the cable, if anyone can help.

kmnov2017

27 Jul 2020, 13:59

Spewing of text can happen for the following reasons

1. The chassis is not grounded properly.
2. The converter you built has a short.
3. The original controller on the keyboard is faulty.

To check the chassis grounding, use a loose piece of cable, connect one end to the shiny back plate (you can use tape to stick it on to the back) and connect the other end to GND on the teensy.

If that doesn't work, double check the teensy you've built. Check all connections and joints and make sure there's so solder bridge.
If it still doesn't work, use the internal converter method.

I'd start with this first before trying to diagnose point 3.

Athen

27 Jul 2020, 14:29

kmnov2017 wrote:
27 Jul 2020, 13:59
Spewing of text can happen for the following reasons

1. The chassis is not grounded properly.
2. The converter you built has a short.
3. The original controller on the keyboard is faulty.

To check the chassis grounding, use a loose piece of cable, connect one end to the shiny back plate (you can use tape to stick it on to the back) and connect the other end to GND on the teensy.

If that doesn't work, double check the teensy you've built. Check all connections and joints and make sure there's so solder bridge.
If it still doesn't work, use the internal converter method.

I'd start with this first before trying to diagnose point 3.
Thanks for the help, though no luck.
IMG_20200727_222814.jpg
IMG_20200727_222814.jpg (2.03 MiB) Viewed 1035 times
It seems to be spewing less, though. It's currently outside of it's chassis. There are no shorts on the teensy, from what I can tell.

Edit: I tried grounding it again, and it seemed to make no difference, as it just started spewing fast again.

kmnov2017

27 Jul 2020, 14:49

Do you have all the keycaps installed on the keyboard or are you testing this with the keycaps removed?

Also, test by directly wiring up the teensy to the original controller, it seems the original cable is damaged from one of the pics you've posted.

Athen

27 Jul 2020, 15:02

kmnov2017 wrote:
27 Jul 2020, 14:49
Do you have all the keycaps installed on the keyboard or are you testing this with the keycaps removed?

Also, test by directly wiring up the teensy to the original controller, it seems the original cable is damaged from one of the pics you've posted.
I'm testing with the keycaps installed, and yeah, I definitely need to fix the cable, the grounding nut cable connector-wire actually snapped off whilst trying to keep it in place. I'm not sure how to fix the cable without absolutely ruining it.

I'll definitely try wiring the teensy from inside when I have the time to

User avatar
hellothere

28 Jul 2020, 00:44

First, because I'm not someone who really fooled around with electronics, I really appreciate kmnov2017's comment about grounding. Because ...

I also have a Model F XT that does a similar thing: if you press one of about 11 keys, the keyboard will register multiple random keystrokes. In my case, though, I didn't have a foam panel installed and a couple of the flippers and springs are really old and ratty, so I was writing off on the problem until I can get some proper thickness foam and new springs/flippers.

Before I started playing around with disassembly of the Model F, I did watch a bunch of videos and saw a bunch of picture archives. One of the things that I thought was a good idea was to hook up the main board to a computer and use a flipper to touch each contact to see if the key registers properly. I think I'm going to do that after I do an ultrasonic cleaning of the flippers and wipe down the contacts with 90% alcohol.

Can't help you much about fixing the cable, but I can say that the tutorials I saw didn't look too terrible hard: strip the cable, reconnect, solder and/or heat shrink. Where you have the break doesn't look especially fun, though.

Athen

28 Jul 2020, 11:36

hellothere wrote:
28 Jul 2020, 00:44
First, because I'm not someone who really fooled around with electronics, I really appreciate kmnov2017's comment about grounding. Because ...

I also have a Model F XT that does a similar thing: if you press one of about 11 keys, the keyboard will register multiple random keystrokes. In my case, though, I didn't have a foam panel installed and a couple of the flippers and springs are really old and ratty, so I was writing off on the problem until I can get some proper thickness foam and new springs/flippers.

Before I started playing around with disassembly of the Model F, I did watch a bunch of videos and saw a bunch of picture archives. One of the things that I thought was a good idea was to hook up the main board to a computer and use a flipper to touch each contact to see if the key registers properly. I think I'm going to do that after I do an ultrasonic cleaning of the flippers and wipe down the contacts with 90% alcohol.

Can't help you much about fixing the cable, but I can say that the tutorials I saw didn't look too terrible hard: strip the cable, reconnect, solder and/or heat shrink. Where you have the break doesn't look especially fun, though.
kmnov2017's comment definitely helped me as well, but I could only wish the solution was that simple.
I only know the minimum of electronics, so I'm pretty much useless.
I really don't want to take the board apart again, but I just may have to re-restore the keyboard to have a fresh start. I'm not too worried about the capsense pads not functioning, since when the keyboard wasn't throwing a tantrum, I had the chance to test all of the keys.
Cleaning the flippers may be a good idea, I did give each one a wipe and a quick bath in very diluted soapy water, which in hindsight may have not been the best idea, but it worked out in the end.

And oh boy, the cable. Its not going to be fun, as upon further inspection, the wire seems to have snapped somewhere inside the cable as well, as there is no connection between the ground on the keyboard to the once attached nut-connector. I'm currently considering just doing an in-case conversion and purchasing a long and thick USB cable to coil myself. It sucks that the cable I have seems to be an earlier one, which means it's prone to fail sometime.
Anyways, I'll keep at it, good luck with yours!

kmnov2017

28 Jul 2020, 11:45

You do not need to take the board apart again. You only need to wire up the teensy directly to the pins on the controller.
Also cleaning the the flipper with soapy water is not a good idea. The original flippers have a coating to make them electrically conductive - I am not sure if soapy water has any effect on them or not, probably not.

Athen

28 Jul 2020, 11:54

That's good to know, I really don't want to take the board apart for another year or so. I'll be doing the conversion once I figure out the pins, and have some time to sink into soldering, still recovering from a burn from trying to desolder old wires from it.
Washing the flippers in soapy water haven't done anything to them, from what I can tell- I'll keep you updated.
I used hand soap, which may have been gentler on it, fingers crossed.

Athen

28 Jul 2020, 12:01

Quick question, when I'm doing an in-chasiss conversion, should I keep the pull-up resistors? Since it's so close, I think I should omit them, right? Or should I keep them incase the signal is still rocky?

kmnov2017

28 Jul 2020, 13:06

For all my past model F conversions, I've never used pull up resistors.

User avatar
ZedTheMan

28 Jul 2020, 15:23

And conversely, I've always used them. Yeah, in a lot of cases you probably don't need it, but if you do you'll be thankful and it will help keep things reliable for longer, I reckon.

User avatar
hellothere

29 Jul 2020, 02:59

kmnov2017 wrote:
28 Jul 2020, 11:45
The original flippers have a coating to make them electrically conductive - I am not sure if soapy water has any effect on them or not, probably not.
I was under the impression that they used a special plastic embedded with conductive material, rather than a coating of some kind. You may be right, though. I offer no guarantees that anything I type is correct.

I wonder if I could start a business where I sold flippers for Model Fs that were made out of copper/silver/gold and charged $100 per flipper. That'd be cool. Actually, I wouldn't be surprised if somebody already did.

Athen

29 Jul 2020, 15:34

ZedTheMan wrote:
28 Jul 2020, 15:23
And conversely, I've always used them. Yeah, in a lot of cases you probably don't need it, but if you do you'll be thankful and it will help keep things reliable for longer, I reckon.
That seems reasonable, I'll probably keep them, thanks!

Athen

29 Jul 2020, 15:42

After some wrangling with my teensy, I haven't gotten to soldering it inside, but before I took it apart, I noticed that the teensy may be the problem. I am not completely sure if it's an official one, or an imitation, but it's probably the latter. Small bumps to the controller seem to cause it to spew uncontrollably, or rather, even more so than before. I am not sure if this is an inherent thing for micro controllers (I don't think it would be?).
Oh, and I fixed the cable temporarily by tying the remaining strands of wire to another wire, which is working for the time being. I checked it's connection through the cable. Whilst I was checking though the keyboard, is the nut-connector supposed to be connected to ground, or is is just for the metal shielding on the din connector? As I have noticed that there is no connection between ground and the nut-connector.

JBert

31 Jul 2020, 10:36

If you're talking about that little metal plate clamping onto the cable: I'm pretty sure it's not connected to anything and is just meant to keep the cable inside. Only the little frayed wire with the loop on the end is connected to the cable's shield.

Another question though: how are those resistors wired? They seem to sit between the d0 pin and the cable, which would not be correct.

Coeus

31 Jul 2020, 19:52

Athen wrote:
27 Jul 2020, 13:37
Currently, I have built a teensy 2.0 Soarer's converter...
How much building to you have to do? Are the surface mount components already soldered?
Athen wrote:
27 Jul 2020, 13:37
...first without the pull-up resistors, and now with resistors...
Further to JBert's post, surely pull-up resistors are connected between a data pin and the supply voltage (VCC)?
Athen wrote:
27 Jul 2020, 13:37
I would purchase an orihalcon converter, but it is absurdly expensive for me right now, as shipping is over $60. So making one was way cheaper.
So I think you're describing the thing I got, this item on eBay: https://www.ebay.co.uk/itm/302711725609 It's described there as Soarer's converter despite everything else I have read describing that as a DIY project. So is orihalcon converter a recognised name?
Athen wrote:
27 Jul 2020, 13:37
Update: funny this, upon closing the keyboard, the ground connector snapped off- so now I also need help with repairing the cable, if anyone can help.
Looking at your picture, I wonder if this has been inexpertly repaired before. On yours the coiling of the cable seems to begin right at that metal plate. On mine there is about 100mm (about 4") of straight cable between the grommet on the keyboard and where the coiling starts. I also wonder if this ground connection is actually to a screen on that cable. As I don't have the problem with the fallen-ff ground wire I don't propose to strip mine back to find out but I think you will probably have to do that in one direction or the other and then, having re-attached the ground wire, put heatshrink over it to keep it neat and secure.

Other than that I am following this because I had a brief period with my Model F that sounds very similar. A couple of times the PC received a bunch of spurious keystrokes in quick succession and a couple of times the keyboard simply stopped working. In each case, unplugging the USB cable between the converter and the PC solved it. It's working fine again now - I am typing on it now, and worked fine for about a week and a half before that.

kmnov2017

31 Jul 2020, 22:31

I just looked at the pics again. Your pull up resisotrs are wrongly set. I'd just remove them completely ...and try again ...

Athen

01 Aug 2020, 13:37

Damn, ok- I'll keep you updated.

User avatar
hellothere

02 Aug 2020, 00:50

Coeus wrote:
31 Jul 2020, 19:52
So I think you're describing the thing I got, this item on eBay: https://www.ebay.co.uk/itm/302711725609 It's described there as Soarer's converter despite everything else I have read describing that as a DIY project. So is orihalcon converter a recognised name?
Yup. The converters he sells are Soarer's Converters just in really, really nice packages. I've bought at least three from him for IBM Model M, IBM Model M with a 90-degree connector, and one for an IBM Model F. I've also bought countless springs and some switches.

I've not tried to make a Sorarer's converter with a Teensy. My hobby is trying to fix keyboards to later sell them. I probably could make a Soarer's Converter and put it into an Altoid's tin or something, but I guarantee I can't make it look as nice as the ones orihalcon sells.

kmnov2017

02 Aug 2020, 01:04

hellothere wrote:
02 Aug 2020, 00:50
Coeus wrote:
31 Jul 2020, 19:52
So I think you're describing the thing I got, this item on eBay: https://www.ebay.co.uk/itm/302711725609 It's described there as Soarer's converter despite everything else I have read describing that as a DIY project. So is orihalcon converter a recognised name?
Yup. The converters he sells are Soarer's Converters just in really, really nice packages. I've bought at least three from him for IBM Model M, IBM Model M with a 90-degree connector, and one for an IBM Model F. I've also bought countless springs and some switches.

I've not tried to make a Sorarer's converter with a Teensy. My hobby is trying to fix keyboards to later sell them. I probably could make a Soarer's Converter and put it into an Altoid's tin or something, but I guarantee I can't make it look as nice as the ones orihalcon sells.
They aren’t worth the price, considering pro micros cost like 3 bucks.

User avatar
hellothere

02 Aug 2020, 18:01

It depends on how you look at it. How long would it take you to put one together? And, as I mentioned, do you think it'd look nice enough to sell to somebody? If you can make some that look as nice as orihalcon's for 1/4 or 1/2 the price, I'd be more than willing to send you cash. Really. I'm absolutely serious. I probably buy one every month.

kmnov2017

02 Aug 2020, 21:05

It takes about 5 mins to make one. And obviously these are for internal use.

If you want to make these for commercial purpose. - Check alibaba. You can find companies that can make you these for under 10 USD shipped.

Coeus

02 Aug 2020, 23:17

hellothere wrote:
02 Aug 2020, 00:50
Yup. The converters he sells are Soarer's Converters just in really, really nice packages. I've bought at least three from him for IBM Model M, IBM Model M with a 90-degree connector, and one for an IBM Model F. I've also bought countless springs and some switches.
Good to hear your experience of these has been good. The orihalcon is certainly very neat and that was part of the attraction. Having researched the teensy a little more, the AtMega 32U4 microcontroller used is very small. The USB A plug on the orihalcon is slightly fatter than usual so I would guess that it has been included in there.

Unfortunately, I am beginning to suspect mine has a fault. A few days back I reported that, after about a week and half of fault-free operation, I had a period with spurious characters which then seemed to go away again. This happened again Yesterday and this time I found that moving the cable seemed to make a difference. After trying flexing the cable at various points along the length from the keyboard all the way to the USB A plug I found a point about 30mm from the USB A plug, i.e. the cable that is part of the converter, where flexing the cable can cause either spurious characters or for the keyboard to stop working.

I know people have commented that this is usually a grounding issue, and it is possible this could be my fingers inducing noise, but it seems more likely this is dodgy connection and, as it's moulded, I can't repair it. I've opened an eBay return case and we'll see what happens.

Coeus

02 Aug 2020, 23:28

kmnov2017 wrote:
02 Aug 2020, 21:05
It takes about 5 mins to make one. And obviously these are for internal use.
The teensy looks like a hobby/prototyping board and this keyboard converter is just one of it's uses so I am not sure I'd say it was specifically designed for internal use but, depending on the keyboard, mounting it internally could produce a very neat result. In that respect it rather depends how authentic you want to be - Athen, who started this thread, wasn't keen to have to replace the original, coiled, IBM cable with something else so that would preclude internal mounting. Also, on the PC/XT Model F without lights, if you miss the lights you could add them to a converter in an external box. You could do that with an internal converter too but then you'd have to drill the plastic housing to make them visible. Another possibility, of course, would be to find (or write) sometime for the PC to show the state of the lights there (on systray/panel).

User avatar
hellothere

03 Aug 2020, 01:33

I did a little spin around the internet. ATM, Pro Micros are $17 to $22 US and a Teensy 2.0 is $16 (I will note that there are probably some other Teensy++ compatible boards out there). I'm also thinking along the lines of what Coeus said: neither OP nor I want to sacrifice an original cable. As an example, OEM IBM cables are $15 to $25 at Unicomp. A 5-pin DIN female to male cable is $8 or so on Amazon.

Yes, prices are lower on AliExpress. You can get a fake Teensy 2.0 for $5 + $5 shipping and a 5-pin DIN female to male cable for about the same, with another $1.32 for shipping. I'd still need a case, though.

FWIW, if you have something really esoteric, like a Tandy 1000 with the (IIRC) DIN 6 connector, that'd probably be an excellent use case for getting a Teensy. I might even try AliExpress and their 30 to 80 day shipping, just to give a Teensy a try. Taking apart and reassembling keyboards is my hobby. Let's extend that to some electronics :D.

Coeus

05 Aug 2020, 01:00

So going back a little, and ignoring the issue of the pull-up resistors, I had a thought - protective earth vs. signal ground.

Looking inside the keyboard enclosure, where the cable enters there is a separate wire that goes to a toothed eye, the same one that is in the 4th of Athen's original pictures and subsequently fell off. When this is properly attached it goes around one of the two screws that fix the metal plate on the bottom of the keyboard. The metal plate also has a ring around where that screw goes that is not painted (or has had the paint removed) so that toothed eye can make contact with that plate. At the other end of the keyboard cable this wire is connected to the metal shell of the 5 pin DIN plug. On the pinout for this plug on the PC & XT the shell is "proective earth (PE)".

So there is no connection inside the keyboard between this and the signal ground which is pin 4 on the 5 pin DIN plug. When connected to an original PC, presumably this protective earth is actually connected to earth. In the orihalcon converter this protective earth seems not to be connected to anything and there is no mention in the original Soarer's instructions about connecting it - that only mentions the signal ground.

So the obvious question is whether this is an issue. Certainly there is no point in worrying about that connection at the keyboard end if it is not connected to anything at the converter end. Or would it be wise for the converter end to tie this to signal ground to avoid the possibility of this plate acting as an antenna?

Athen

07 Aug 2020, 08:45

I got some time to remove the incorrect resistor, and that hasn't been able to fix anything.

I haven't deticiated an hour yet to trying an in-chasiss conversion, which I'll be doing very soon.

I have temporarily fixed the shielding (?) connector with some wire.

I'm not well versed in electronics, but the problem might be because I'm using a laptop- due to their poor grounding, but others seem to have gotten it working.

Anyways, this was a quick update, I'll post when I have done the in-chassis conversion.

Edit:
I'm starting to suspect that it might be the teensy, since it seems to glitch, more frequently, if there is any movement or impacts around it's enclosure.

Edit 2:
Help, my enter is stuck on Shift+Enter for some reason, I don't know how to change it back

Post Reply

Return to “Keyboards”