IBM 5251 restoration (rebuilding phase)

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snacksthecat
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05 Jun 2019, 23:59

adamcobabe wrote:
05 Jun 2019, 11:26
Interesting. Seems a little risky to me given there is minimal stock to replace them if you mess up (from Orihalcon at $10 each). Did you bend the fly plate in the image?
I can't recall if I bent that one or if it was like that.

I decided to just do it because the keys felt uneven. To be honest, about 90% of them were perfectly fine. Most of the remaining 10% were only slightly off from the 1/2" sweet spot. A sad few had bad bends.

Image

Probably the more worthwhile activity for someone to do would be testing each key for feel, then doing the spring shaping only on the ones that felt off.

So now I have to put all these fly plates back on. The IBM manual again has some details on how to do this efficiently.

Image

I've been doing pretty much how the document says to. I used a small allen wrench because it's fatter than a paper clip so it doesn't slip away as easily. I mounted it vertically using a clamp so that I could use two hands to maneuver the switch around. Here's a visual:

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snacksthecat
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07 Jun 2019, 06:01

I'll have to do a deep cleaning of the edge connector. It is in pretty bad shape. Luckily this junk comes off pretty easily with a little bit of alcohol and something pokey.

Image

Image

SneakyRobb

07 Jun 2019, 16:36

snacksthecat wrote:
07 Jun 2019, 06:01
I'll have to do a deep cleaning of the edge connector. It is in pretty bad shape. Luckily this junk comes off pretty easily with a little bit of alcohol and something pokey.

Image

Image
Isn't the silver there the solder finish to protect the copper trace layer under from oxidation? I wonder if this will affect long term connectivity.

Regardless your rebuild looks very good. Your team work to remove the switch stem is pretty great. I have removed those on my own and accidentally sliced my fingers open a few times. By far and away the hardest and only real dangerous part of the operation.

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snacksthecat
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07 Jun 2019, 17:42

SneakyRobb wrote:
07 Jun 2019, 16:36
Isn't the silver there the solder finish to protect the copper trace layer under from oxidation? I wonder if this will affect long term connectivity.
Yeah, unfortunately it still doesn't work with xwhatsit. Not sure what to do from here.

SneakyRobb

07 Jun 2019, 19:26

snacksthecat wrote:
07 Jun 2019, 17:42
SneakyRobb wrote:
07 Jun 2019, 16:36
Isn't the silver there the solder finish to protect the copper trace layer under from oxidation? I wonder if this will affect long term connectivity.
Yeah, unfortunately it still doesn't work with xwhatsit. Not sure what to do from here.

Hi, that is most unfortunate. It sort of looks like the traces above your last shot corroded away? I would imagine if that is so they would not return signal.

It would cost you perhaps $50 +import/etc but you could always make a new PCB for it. I have had success making new beamspring PCBs with DMA and Wcass help.

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snacksthecat
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07 Jun 2019, 21:39

SneakyRobb wrote:
07 Jun 2019, 19:26
Hi, that is most unfortunate. It sort of looks like the traces above your last shot corroded away? I would imagine if that is so they would not return signal.

It would cost you perhaps $50 +import/etc but you could always make a new PCB for it. I have had success making new beamspring PCBs with DMA and Wcass help.
I'm hoping it's still salvagable in some way. Either fixing the connector or using different firmware. In xwhatsit, it seemed like all of the rows of keys worked, but at different voltage thresholds. As far as I know, you can't set a different threshold for each key with that firmware. I know in CommonSense you can do that. I will probably explore that route before looking into designing the PCB. Though, are there any footprint libraries you know of?

SneakyRobb

07 Jun 2019, 22:03

snacksthecat wrote:
07 Jun 2019, 21:39
SneakyRobb wrote:
07 Jun 2019, 19:26
Hi, that is most unfortunate. It sort of looks like the traces above your last shot corroded away? I would imagine if that is so they would not return signal.

It would cost you perhaps $50 +import/etc but you could always make a new PCB for it. I have had success making new beamspring PCBs with DMA and Wcass help.
I'm hoping it's still salvagable in some way. Either fixing the connector or using different firmware. In xwhatsit, it seemed like all of the rows of keys worked, but at different voltage thresholds. As far as I know, you can't set a different threshold for each key with that firmware. I know in CommonSense you can do that. I will probably explore that route before looking into designing the PCB. Though, are there any footprint libraries you know of?
Hi, There is a series of videos from user "red'

viewtopic.php?f=7&t=20375

https://youtu.be/CNPMcrKGtd4
With his repository in the description
github.com/redvers/modelf

User avatar
adamcobabe

08 Jun 2019, 16:14

I had an issue with the 5251 where the Xwhatsit would slide side to side and contact the wrong trace pads, though that was more of a columns issue. Long shot, but I am wondering if maybe the plating is affecting the capacitance as nickel is ferromagnetic. I'm not an expert in physics though so, maybe just ignore me. ;) Nickel is used in electronics all the time, right? You could also just test without the foam to make sure the extra thickness isn't pushing differently for certain rows.

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snacksthecat
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10 Jun 2019, 03:09

Holy cats. It's the nickel plating.

I have a second 5251 that I finally brought out of storage. I swapped different parts in and outbetween the two boards. For instance, I tried the "new" pcb with the old plate/switches. It kind of worked, but the bottom row was dead and the voltage threshold didn't make sense. So then I tried the new keyboard on it's own, without swapping any parts between the two. It worked perfectly I'm 99% sure this is the problem.

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