Help adapting the NCR 4950

consideringquiet

15 Jul 2018, 19:36

Okay so the fella from reddit told me to cut the JO jumpers on the board. Ought I do it?

User avatar
TheInverseKey

15 Jul 2018, 21:08

consideringquiet wrote: Okay so the fella from reddit told me to cut the JO jumpers on the board. Ought I do it?

Yeah that is who I got the photos from so I would give it a shot. He seemed quite knowledgeable about this conversion.

consideringquiet

16 Jul 2018, 01:11

TheInverseKey wrote:
consideringquiet wrote: Okay so the fella from reddit told me to cut the JO jumpers on the board. Ought I do it?

Yeah that is who I got the photos from so I would give it a shot. He seemed quite knowledgeable about this conversion.
So on the board the JO1 jumper was already cut, but I think there may be some more on the board as another jumper says JO3.

User avatar
TheInverseKey

25 Jul 2018, 23:12

consideringquiet wrote:
TheInverseKey wrote:
consideringquiet wrote: Okay so the fella from reddit told me to cut the JO jumpers on the board. Ought I do it?

Yeah that is who I got the photos from so I would give it a shot. He seemed quite knowledgeable about this conversion.
So on the board the JO1 jumper was already cut, but I think there may be some more on the board as another jumper says JO3.

I have an update on this board and the information about the jumpers and the voltage regulator. I thought that this board looked familiar and that it was a board that was rebranded for a bunch of other companies that would be using them for their terminals. Well it turned out I was right when I recently purchased an ADDS ASCII and it had all of the jumpers already in place. Now mine didn't come with the voltage regulator so it just take the 5 volts.

Jumpers:
Here is a picture of the jumpers that came on my ADDS ACSII
Spoiler:
Image
Voltage regulator:
I also have a NMB PC 122 with a voltage regulator and this board according to others on the forum needs more than the regular 5 volts. These NMB/Hi-Tek boards needs 9 volts because they are meant for a terminal that would be able to supply it.


Going to be using a teensy to convert this rather than use the cable that came with it because it was not in the greatest condition. Will be reporting back once I have the converter done and or issue/other information that I find.

User avatar
TheInverseKey

26 Jul 2018, 02:01

Update here is the pinout for converting it after the jumper wires have been put in.

This is based on the at rj11 conncector that came with my board. For a better understanding have a look at the picture of when it is connected to a teensy.
Top
6 = reset - red
5 = data - green
4 = case gnd - black shielded
3 = clock - yellow
2 = sg gnd - black shielded
1 = vcc +5v - white
Bottom

Top is the original cable and the bottom is the teensy cables:
Spoiler:
Image

consideringquiet

28 Jul 2018, 05:34

Well i cut the jumpers and no dice. I suppose this project might be dead in the water for me now. I cant get a teensy in time for college nor do i have the equipment or knowledge to really wire one together.

Any last ditch ideas to deal with the power issue?

User avatar
TheInverseKey

28 Jul 2018, 22:50

consideringquiet wrote: Well i cut the jumpers and no dice. I suppose this project might be dead in the water for me now. I cant get a teensy in time for college nor do i have the equipment or knowledge to really wire one together.

Any last ditch ideas to deal with the power issue?
There is 2 options I think:

Here is something that another user said to use to get the correct voltage. This should bump the voltage to 9v but I would check to see how much is going to the controller before doing anything.
https://www.pololu.com/product/2116

Or you could remove the voltage regulator and see if it works with the normal 5v but there is a bit of difference in the components used between your board and mine. You would have to find all of the missing components that are different to make it work.

consideringquiet

29 Jul 2018, 20:52

TheInverseKey wrote:
consideringquiet wrote: Well i cut the jumpers and no dice. I suppose this project might be dead in the water for me now. I cant get a teensy in time for college nor do i have the equipment or knowledge to really wire one together.

Any last ditch ideas to deal with the power issue?
There is 2 options I think:

Here is something that another user said to use to get the correct voltage. This should bump the voltage to 9v but I would check to see how much is going to the controller before doing anything.
https://www.pololu.com/product/2116

Or you could remove the voltage regulator and see if it works with the normal 5v but there is a bit of difference in the components used between your board and mine. You would have to find all of the missing components that are different to make it work.
Thanks! I'll definitely take a look, but also it seems like there was a miscommunication between me and the reddit fella. I was supposed to cut the JA wires and leave the JO alone. I needed to solder the JO jumpers anyway since one was cut and another didn't have a jumper to begin with. so I'll be up to trying that.

If this doesnt work I'll move onto those options. I really hope i can get this working before the end of august!

consideringquiet

15 Sep 2018, 23:25

I'm starting to think I should just delegate these projects to other people... Whenever I touch things like this they just turn to trash. I'm like the Midas of breaking keyboards I swear

The guy off Reddit pointed out that I had the correct wiring, and said I likely fried the board. What do I do now?

User avatar
snacksthecat
✶✶✶✶

16 Sep 2018, 00:20

Image

consideringquiet

18 Sep 2018, 23:23

snacksthecat wrote: Image
Right?

User avatar
snacksthecat
✶✶✶✶

19 Sep 2018, 01:50

No but really if you desolder the IC on it and replace it with a Teensy++ 2.0, you'd have a fully programmable keyboard. And there's no chance of frying the board because, well, there's nothing to fry!

consideringquiet

25 Jan 2019, 02:17

So, I haven't yet given up this project. The whole wiring a PS/2 cable is out the window, though. I'm considering replacing the IC altogether. However, I'm unsure if my testing on this board borked it all together.

consideringquiet

25 Jan 2019, 02:22

snacksthecat wrote:
19 Sep 2018, 01:50
No but really if you desolder the IC on it and replace it with a Teensy++ 2.0, you'd have a fully programmable keyboard. And there's no chance of frying the board because, well, there's nothing to fry!
So, my friend found a pinout for the original IC online. Would we theoretically just match the pins there and go on from there?

Do you have any tips on converting the IC to teensy? It's my first time for this sorta thing.

consideringquiet

30 Jan 2019, 02:52

So I made one last effort to adapt this without completely removing the IC. My friend helped me resolder some shoddy jumpers of mine and remove certain resistors and capacitors to match theinversekeys pcb. After wiring the teensy, we got stuck on the fact that the keyboard would power on, but not send any signals back to the PC. Using HID sense we found that the keyboard would spit out a wEE error and wouldn't be recognized as AT.

My friend tried a whole manner of different pin combinations aside from sgn gnd and vcc, but no dice. We tested the capacitors inboard, one was not putting out anything through the multimeter but replacing it didn't help.

I'll post some photos of the new wire job. I'm thinking I might have to replace an IC, which would be mighty useful.

consideringquiet

30 Jan 2019, 03:05

There's always the possibility I borked this damn thing into a Kentucky fried paperweight when I was feebly attempting to adapt it to PS2 earlier. What should I do now? I thought the pinouts were correct. I don't want this thing going to waste, I got it NOS.

Next best thing I can think is completely desoldering either the IC or PCB.
Attachments
IMG_20190129_182917.jpg
IMG_20190129_182917.jpg (3.1 MiB) Viewed 350 times
IMG_20190129_182932.jpg
IMG_20190129_182932.jpg (3.39 MiB) Viewed 350 times
IMG_20190129_183518.jpg
IMG_20190129_183518.jpg (3.12 MiB) Viewed 350 times
IMG_20190129_182939.jpg
IMG_20190129_182939.jpg (3.87 MiB) Viewed 350 times
IMG_20190129_183513.jpg
IMG_20190129_183513.jpg (2.98 MiB) Viewed 350 times

consideringquiet

11 Sep 2019, 23:28

Bump, still haven't gotten around to replacing the IC since I can't find the original pinout chart online for the chip.

Anybody have any experience with this?

Post Reply

Return to “Keyboards”