122-key Model M, P/N 1394104 — keys not registered AT ALL

[jafd]

I've got this 122-key monster a few days ago. It had an RJ-45 connector, and I only had USB, so all I could do was cut the cable, and solder a Teensy with Soarer's firmware on it, which I did.

I also cleaned it thoroughly. In the hindsight, maybe I shouldn't have. The fact is: the Teensy itself works, but no keys whatsoever are registered. I checked pinout and wire coloring twice before I soldered it, so getting Vcc and ground is ruled out. I also checked with a multimeter that joints themselves are OK — they deliver 5V to the controller. So, it must be either membrane or controller.

While cleaning, I did unscrew the controller from its place, and reseated the membrane connections. The membrane itself is quite old, and the connection points are blackened with oxidation, except for the parts that actually make contact with the connector — they look like polished silvery spots.

So, I don't know if it's the controller that's dead, or is it the membrane. To replace the membrane, I'd need to actually do the full bolt mod, because the rivets will have to go, too. I'm a bit reluctant to do that.

Also, if I replace everything — say, order a new controller from Phosphorglow, a new membrane from Unicomp, etc — it will be a hefty premium. So I want to positively rule out which component is at failure.

The question thus is: how do I do that? I thought about connecting the controller, sans membrane, to the Teensy, running hid_listen, and trying to short rows and columns at the connector itself to emulate keypresses. If it's the membrane, the controller would register keypresses. If the controller is dead, well, it's dead.

Or go through the pains of checking continuity at the membrane itself. Still a pain, as I would have to take it out (and order all the nuts and bolts).

Suggestions welcome.

[suicidal_orange]

It sounds unlikely that the whole membrane would fail so assuming you've pressed lots of keys the controller is probably at fault.  Shorting rows to columns is a free and easy test so you have nothing to lose and if it's dead you might have an easy, though not cheap, fix.

If the controller's not dead you could try cleaning or reseating the membrane connector - you might just have the shiny spots not in the exact place they come from (I've never opened a BS board so this may be impossible - skip if it is)

Also how small is the membrane connector?  You could borrow a friend to press some keys while you check continuity at the connector, if it's not too small.  Sounds easier than a full bolt mod at least...

[jafd]

I think a multimeter's pin would still fit when the membrane is in.

Too bad I'm on the road and will be able to test only on Monday.

Another thing... Are there microcontroller solutions that don't rely on the previous controller, but able to wire in and decode the whole matrix? If the controller's dead...

(Also, the steel plate will need an un-rusting, so a bolt mod is imminent at some point.)

[jafd]

It sounds unlikely that the whole membrane would fail so assuming you've pressed lots of keys the controller is probably at fault.

I pressed all of them. Several times each. The problem can be that, for example, all rows/columns connection failed, not entirely impossible.

[jdcarpe]

I think you're putting too much effort into what is basically a $40 keyboard. You've probably already spent in your own labor more than the keyboard is worth. Maybe just get a new one?

[jafd]

Where do you get a new 122-key Model M? And no, Unicomp makes crap compared to the real thing.

I totally knew what I was going for. I want it repaired, and yes, some investment is needed. But there's the fun of it.

[Snowdog993]

I would suggest you get a Colossus Controller with USB cable for the M-122.

http://phosphorglow.net/store/products/universal-model-m-usb-controller/

That might be the best way to go!

[jdcarpe]

Where do you get a new 122-key Model M? And no, Unicomp makes crap compared to the real thing.

I totally knew what I was going for. I want it repaired, and yes, some investment is needed. But there's the fun of it.

I understand the whole "it's about the journey not the destination" thing, but sometimes you fight a losing battle.

http://www.ebay.com/itm/271832202316

It's being sold by GH user orihalcon. You could PM him here for a discount.

[jafd]

Going to cost me a fortune in shipping and import duties. Even when I order phosphorglow's controller, membrane from Unicomp, and all the things needed to bolt mod it, I'll still spend *less*.

[Snowdog993]

Going to cost me a fortune in shipping and import duties. Even when I order phosphorglow's controller, membrane from Unicomp, and all the things needed to bolt mod it, I'll still spend *less*.

Before you rip apart the thing, try the controller first.  Hopefully there is nothing wrong with the membrane at all.

[jdcarpe]

Going to cost me a fortune in shipping and import duties. Even when I order phosphorglow's controller, membrane from Unicomp, and all the things needed to bolt mod it, I'll still spend *less*.

Ah, okay, carry on then. I didn't realize you were international. We are blessed with a proliferance of cheap vintage IBM here in the US, it seems.

[jafd]

An update.

I took a piece of wire, unplugged the membrane, and started poking around, shorting rows and columns (I presume the narrow and the wide sockets, respectively). hid_listen did not produce *anything*, so my bets are the controller is dead. I'm left with the option of ordering a controller from Phosphorglow, but he doesn't seem to answer messages lately... Any other source of controllers like his?

I'll order a new membrane from Unicomp, anyway. Bolts and nuts are en route, and dremel purchase is due today.

[jafd]

Phosphorglow seems AWOL, so will try to assemble something of my own.
Teensy++, then, FFC connectors...

[SamirD]

You may be able to get a controller from an otherwise trashed 122.  That might be the quickest way to get you back on the road to getting it to work.  Good luck!

[Snowdog993]

You may be able to get a controller from an otherwise trashed 122.  That might be the quickest way to get you back on the road to getting it to work.  Good luck!

Do you actually own a 122?  The only 122's that will work with a PC are the Terminal Emulation 122's.  If you plan on getting an IBM 122 terminal board, you will need to replace the controller (Colossus or do a teensy mod) or get an Orihalcon adapter for it. 

A trashed 122?  Are you talking about the Lexmark or Unicomp or Affirmative emulation keyboards?  They have a 4th gen controller unlike the original 122-key keyboards.

Let me see I might have a picture of a 122 (emulation) controller somewhere around here.
Here it is. 

Edit: Note that the Status LED's are on it. 
It would go in the upper right side on the front of the steel plate.
Not in the traditional center-backside of the steel plate.



Unlike the actual 122 controller pictured here:



And the Colossus Controller that would work with it:



There is an enormous difference!

Note: This is a picture of the 1391401 external USB model, the actual one would have the 5-pin internal header to a USB cable.

[SamirD]

You may be able to get a controller from an otherwise trashed 122.  That might be the quickest way to get you back on the road to getting it to work.  Good luck!

Do you actually own a 122?  The only 122's that will work with a PC are the Terminal Emulation 122's.  If you plan on getting an IBM 122 terminal board, you will need to replace the controller (Colossus or do a teensy mod) or get an Orihalcon adapter for it. 

A trashed 122?  Are you talking about the Lexmark or Unicomp or Affirmative emulation keyboards?  They have a 4th gen controller unlike the original 122-key keyboards.

Let me see I might have a picture of a 122 (emulation) controller somewhere around here.
Here it is. 

Edit: Note that the Status LED's are on it. 
It would go in the upper right side on the front of the steel plate.
Not in the traditional center-backside of the steel plate.

Show Image

Unlike the actual 122 controller pictured here:

Show Image

And the Colossus Controller that would work with it:

Show Image

There is an enormous difference!

Note: This is a picture of the 1391401 external USB model, the actual one would have the 5-pin internal header to a USB cable.

Thank you for all the clarifications.  I meant a 122 with a ps2 port or terminal adapter to use with the cable convertor, but I didn't know that there were tremendous differences in the controllers.  Good to know!