It's dead, Jim.

hellothere · 12 Jul 2022, 18:30

I purchased an OmniKey 102, a couple weeks back. The main problem: someone physically ripped out the keyboard connector, which removed and lifted a couple of tabs on the PCB where the connector was, then they cut the keyboard cable, just to be extra thorough.

I was able to follow the traces for clock, VCC, etc. from the missing keyboard connector to the correct places on the PCB using a multimeter, checking for continuity. I was able to determine that only ONE trace was bad, the one for clock. Groovy. I soldered in a keyboard connector from another same-age, working OmniKey, then soldered in a wire from the keyboard connector to the end of the trace, which goes to a resistor. Plugged in the keyboard cable from my other OmniKey and used a known-working DIN 5 to PS/2 adapter and connected to my computer (it has a "real" PS/2 port), then started up the computer. No lights on the keyboard. Keys don't do anything. Powered down. Reconnected with a DIN 5 to PS/2, then a PS/2 to USB active adapter. The computer does the USB "noise" indicating that it found something USB, but no worky still. I also tried the computer logged in, then connecting the USB adaptor. Still no worky. I also have a powered USB hub. Still no worky. I have a known-good Hasu TMK adapter, so I tried that. The USB connector noise goes off every second and only stops when I disconnect the TMK. This model OmniKey only has a XT/AT switch and I tried that, too. Still no worky.

It doesn't look like I have any blown caps and everything else looks OK. Anything else I should check? Please note that while I have a multimeter, this does not mean that I know electronics.

XMIT · 12 Jul 2022, 20:42

Sounds like a prime candidate for controller replacement.

hellothere · 13 Jul 2022, 00:11

XMIT wrote: ↑
12 Jul 2022, 20:42
Sounds like a prime candidate for controller replacement.

That's what I've been thinking. I really don't want to.

XMIT · 13 Jul 2022, 04:11

Post photos perhaps?

thefarside · 14 Jul 2022, 15:28

If you have another OmniKey I wonder if you could rule out the controller by replacing it with one from a working keyboard.

hellothere · 15 Jul 2022, 06:18

XMIT wrote: ↑
13 Jul 2022, 04:11
Post photos perhaps?

On the slate for tomorrow.

thefarside wrote:If you have another OmniKey I wonder if you could rule out the controller by replacing it with one from a working keyboard.

First, I want to say that I'm imagining that you are Gary Larson. Hey, everyone needs a hobby. It would please me if Gary Larson was into vintage or modern mechanical keyboards.

Second, the answer is ... maybe? I do have at least one other OmniKey from the same era, but I'm not wanting to reach for the soldering iron quite yet. I also have a parts PCB that's from Focus and may be from about the same era, but I haven't yet compared it to the currently dead PCB.

Muirium · 15 Jul 2022, 12:46

Oh, that's where the bull avatar comes from? I can easily imagine any cartoonist getting into vintage keys. Well, besides Bill Watterson, who'd only get into throwing them into a chipper. :O

thefarside · 15 Jul 2022, 14:10

hellothere wrote: ↑
15 Jul 2022, 06:18

thefarside wrote:If you have another OmniKey I wonder if you could rule out the controller by replacing it with one from a working keyboard.
First, I want to say that I'm imagining that you are Gary Larson. Hey, everyone needs a hobby. It would please me if Gary Larson was into vintage or modern mechanical keyboards.

hellothere wrote: Second, the answer is ... maybe? I do have at least one other OmniKey from the same era, but I'm not wanting to reach for the soldering iron quite yet. I also have a parts PCB that's from Focus and may be from about the same era, but I haven't yet compared it to the currently dead PCB.

I can only speak for my Gold Label OmniKey 102, but it has a removable controller - no soldering needed. Below is a pic of mine which was not working and replaced with a “full size” version thanks to Northgate Bob. The black tape was to prevent sunlight erasing the firmware, but I may have been too late!

: JPEG image 4.jpeg (1.91 MiB) Viewed 2635 times

Polecat · 15 Jul 2022, 17:35

thefarside wrote: ↑
15 Jul 2022, 14:10

I can only speak for my Gold Label OmniKey 102, but it has a removable controller - no soldering needed. Below is a pic of mine which was not working and replaced with a “full size” version thanks to Northgate Bob. The black tape was to prevent sunlight erasing the firmware, but I may have been too late!
JPEG image 4.jpeg

That's actually an EPROM which contains the firmware, but they can go bad or get erased if exposed to UV light with the window uncovered. The controller is a separate 40 pin chip, usually soldered in place.

hellothere · 15 Jul 2022, 18:38

Pics of the problem PCB:

Spoiler:

Pics of a good PCB:

Spoiler:

Notes:
"CDVG" (4 pin white connector) is clock, data, VCC (power), and ground.
SW1 (2 pin white connector) is the AT/XT switch.
Yes, the front/brown side of the PCB has tape all over. This is original.
The green wire on the misbehaving PCB goes from clock to the top wire of R10. I don't know if that's + or -. It's beyond my electronics knowledge.

Thanks to everyone for looking.

Bjerrk · 15 Jul 2022, 19:03

Now, bear with me, this is probably a very silly question.

In the good PCB, is there continuity between these two solder joints?

: good_ng.png (1.31 MiB) Viewed 2570 times

They seem to have flown together in the bad PCB, at least:

: bad_ng.png (651.7 KiB) Viewed 2570 times

(And yes, I was lazy, I haven't followed the traces down the line to check the significance of it

)

BuGless · 15 Jul 2022, 21:36

Bjerrk wrote: ↑
15 Jul 2022, 19:03
In the good PCB, is there continuity between these two solder joints?

In the good PCB they are not connected. It would not have made sense if they would have been connected. If they would have been supposed to connect there, then the traces would have been either completely parallel or there would have been just a single trace leading to both together.

They seem to have flown together in the bad PCB, at least:

Most definitely, yes, and most definitely not good.

Muirium · 15 Jul 2022, 21:46

Correct on both counts. Someone done gone messed it up.

hellothere · 16 Jul 2022, 00:48

Bjerrk wrote: ↑
15 Jul 2022, 19:03
Now, bear with me, this is probably a very silly question.

In the good PCB, is there continuity between these two solder joints?

Possibly silly, but a good question. You were correct that the solder joints were touching. I dragged out my 5X magnifying lamp and re-soldered all the joints. Connected back to my TMK converter and got the Num Lock light to come on. Shut all the way down, just connected AT to my PS/2 adapter and worky, worky! Well, other than the dead switches. I expected a few. So, thank you very much for the silly question!

I seem to have a hardware problem with either the TMK I made, cabling, or some adapter. I had been using the TMK with another OmniKey for a couple days and that just quit working. Same with my PS/2 to USB active adapter: I tried that with both Omnikeys and no worky, but it did a few days ago. Hmmmmm.

Polecat · 16 Jul 2022, 02:40

Good job, guys, glad it's working now!