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geekhack Community => Keyboards => Topic started by: John Boone on Sat, 28 April 2012, 09:01:02

Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: John Boone on Sat, 28 April 2012, 09:01:02: Hi,

I was given for free (well, 4€, the cost for grabbing it at Paris) a somehow defective french AZERTY Model M keyboard. It is a 1993 model very similar to the US 1391401, with a PS/2 detachable cable.

It is in good shape, 3 caps missing, other than that it will look great once cleaned up.

I just plugged it, and it mostly works but some keys produce weird symptoms. To be accurate when i hit one of the offending keys, the next close to it is triggered as well.

For example:
if I press "v" or "b" I get "vb"
if I press "n" or "," I get "n," (on AZERTY layout "," is at the place of "M" on QWERTY)
if I press "Enter" or "Space", I get both

Other weird symptoms :
"*" produce "!*"
"0" on the numpad is silent

Less then 10 keys are concerned, the rest seems behaving normally.

So far I have no real clue of the problem, I opened the keyboard and the inside is relatively clean, the pcb is fine looking with no hack, the 2 electrolytic capacitors look ok.

Is this a known problem of some sort ? What should I look first ? Could it be a simple software problem as i use the keyboard on Linux ? I tried different configurations without any change. So I guess it is an hardware problem..

Thanks for reading, any ideas and comments very welcome ! :)

EDIT: see next page, message #20, for the thumbtacks mod !
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: fohat.digs on Sat, 28 April 2012, 10:18:46: This is a guess, and I am not an electrician, but it would seem that these signals are shorting together, somehow.

I would guess that this a hardware problem rather than a software problem.

One thing to try, although it would require dis-assembly, and a subsequent bolt-mod (no problem if you were planning to do this already, quite a chore if not), would be to look for damage or debris affecting the traces on the membrane under those keys.

As for the 0 on the numpad, try pulling the key and re-seating it (maybe a few times will be required). Also, with the key off, shake the board a bit and see if the spring is standing properly and flopping around the same as the others.
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: tp4tissue on Sat, 28 April 2012, 13:21:49: Quote from: John Boone;584747
Hi,

I was given for free (well, 4€, the cost for grabbing it at Paris) a somehow defective french AZERTY Model M keyboard. It is a 1993 model very similar to the US 1391401, with a PS/2 detachable cable.

It is in good shape, 3 caps missing, other than that it will look great once cleaned up.

I just plugged it, and it mostly works but some keys produce weird symptoms. To be accurate when i hit one of the offending keys, the next close to it is triggered as well.

For example:
if I press "v" or "b" I get "vb"
if I press "n" or "," I get "n," (on AZERTY layout "," is at the place of "M" on QWERTY)
if I press "Enter" or "Space", I get both

Other weird symptoms :
"*" produce "!*"
"0" on the numpad is silent

Less then 10 keys are concerned, the rest seems behaving normally.

So far I have no real clue of the problem, I opened the keyboard and the inside is relatively clean, the pcb is fine looking with no hack, the 2 electrolytic capacitors look ok.

Is this a known problem of some sort ? What should I look first ? Could it be a simple software problem as i use the keyboard on Linux ? I tried different configurations without any change. So I guess it is an hardware problem..

Thanks for reading, any ideas and comments very welcome ! :)

The board is old, probably kept in bad conditions temperature wise. The pcb has likely gone through some thrashing... Check the solder points, and also the traces.

I'm not sure if Model M uses any diodes in the matrixing, but if they're surface mount, they may've broken off.
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: mich on Sat, 28 April 2012, 14:15:00: If you have a bunch of pairs of keys which always fire together no mater which one was pressed, it might be a short between some membrane traces. If you are sure that there is no metal rubbish laying on the PCB and causing short there, try (gently) disconnecting the membranes from PCB and connecting them back. Make sure that they are inserted exactly straight and not skewed.
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: John Boone on Mon, 30 April 2012, 08:53:54: Thanks for your answers !

I cleaned gently the connectors and contacts membranes on the PCB, there was some dust but nothing scary. I measured the 2 electrolytics and there were fine. But it didn't improved the situation. So I am afraid I have to clean the inside and make the bolt mod.

The plastic rivets are all intact but I suspect that some liquid went into the keyboard. Look at this photo:

[ATTACH=CONFIG]49507[/ATTACH]

As you see, there are some splashes around the rivets and this corresponds to where there are faulty keys. The plot thickens !
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: John Boone on Mon, 30 April 2012, 10:56:14: (http://img842.imageshack.us/img842/4788/insidems.jpg) (http://imageshack.us/photo/my-images/842/insidems.jpg/)

Wow, look at the tool I used to remove the rivets in a record time ! Less than a few minutes ! :)

No wonder why this keyboard had problems, some coffee or tee spilled inside, and in large amount !
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: 486 on Mon, 30 April 2012, 16:25:56: This is a late model 1391401 so I suspect it doesn't have any drainage holes. Please correct me if I am wrong. Clean contacts on the traces as well but not with a rubber! Just repeatedly insert and remove the trace from the connector. I suspect you may need to check the capacitors on controller as they are the most common cause of trouble with the PCB.
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: fohat.digs on Mon, 30 April 2012, 16:37:40: I have used plain water and alcohol for cleaning these with no problems. Be gentle.

My problems have almost always come from abrasion and cracking breaking the circuits on the printed traces.

I do think I have gotten 1 bad controller in about a dozen Ms.
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: mich on Mon, 30 April 2012, 17:02:15: Quote from: 486;586646
I suspect you may need to check the capacitors on controller as they are the most common cause of trouble with the PCB.
One of this caps is for power filtering and the other one is a part of delayed start circuit. If they failed, the board probably wouldn't start at all.
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: John Boone on Mon, 30 April 2012, 19:45:02: I checked them with my multimeter, they are in specs. The cause is most probably the membranes, as one was stuck on the rubber film and it caused the whole set to be bended in a weird manner, and in turn leading to bad contacts.

Tomorrow everything will be carefully cleaned, and the last part of trouble, i guess, is the bolt mod. However my deviant mind is working on an alternate procedure, way easier and cheaper. More to come later.
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: fohat.digs on Mon, 30 April 2012, 20:34:38: If the "problem liquid" was water-based, try a gentle water soak to separate the pieces, then clean and dry them carefully.
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: mr626 on Mon, 30 April 2012, 21:35:48: Quote from: John Boone;586327
Show Image
(http://img842.imageshack.us/img842/4788/insidems.jpg) (http://imageshack.us/photo/my-images/842/insidems.jpg/)

Wow, look at the tool I used to remove the rivets in a record time ! Less than a few minutes ! :)

No wonder why this keyboard had problems, some coffee or tee spilled inside, and in large amount !

What tool is that? And how exactly did you use it to remove the rivets?

I found that even with an extra sharp chisel, removing the rivets cleanly is still a challenge.
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: John Boone on Tue, 01 May 2012, 10:41:42: [ATTACH=CONFIG]49625[/ATTACH]

It's a tool to remove paint traces on glass windows after a paint job. This one is an old-school model with a wood handle. I suppose nowadays you will find some plastic ones, disposable, and without the luxury of a central screw to change the blade. Yep there is a sharp blade inside, like a razor blade, taken in sandwich. But the blade is not supposed to be mounted like on the photo. Normally the central hole of the blade is where the screw enters, to safely lock it in place. But i preferred to remove the blade and let the "jaws" just hold it on its border. It is somehow unsafe, and it makes a very dangerous tool. But that way the blade can bend a little. So you can press the blade on the metal back cover and cut the rivet heads almost horizontally.
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: fohat.digs on Tue, 01 May 2012, 19:03:04: I don't know what is for sale in Australia or France, but in the US we have the Xacto knife which is a handle with a slot that accepts many different insert blade configurations.

The "chisel" blade insert is absolutely perfect for this task. $5 for a pack of 5.

Use the "rough" ones for the initial cuts (good for 2-3 boards), then a fresh one to "shave" the rivet posts short and flat, exactly the way you want them. You need steady hands, and reading glasses, but this is far better and cleaner than files, sandpaper, or the like.

In my opinion, this is the best way to protect those alignment crescents that flank each rivet.
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: John Boone on Wed, 02 May 2012, 09:51:21: This X-Acto tool should do fine too. ! But please be carefull with that axe, Eugene ! :)

In the meanwhile i cleaned the membranes and, good news, they are in a good shape with few remaining dirt and oxidation:

[ATTACH=CONFIG]49662[/ATTACH]

Despite the dirt, the multimeter produce a good "beep" on all the points but one...

Here is the contact point that remains oxided and sometimes fails to "beep" :
[ATTACH=CONFIG]49663[/ATTACH]

I tried alcohol and scratching with the back of a sponge for the dish but it was too abrasive and could not even remove the oxidation that seems more profound.

I scratched my head then decided to try a mini-dremel with a polish brush:

[ATTACH=CONFIG]49667[/ATTACH]

It works fantasticly well and you need to pass it just a few seconds, with a magnifier i noticed that most of the points, despite looking ok, had some slight dirt traces:

[ATTACH=CONFIG]49668[/ATTACH]
Before

[ATTACH=CONFIG]49669[/ATTACH]
After !!

So I am going to pass it on all the points , then I will try to clean the one that is really oxided.
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: ch_123 on Wed, 02 May 2012, 10:53:11: Quote from: 486;586646
This is a late model 1391401 so I suspect it doesn't have any drainage holes. Please correct me if I am wrong..

You're wrong and you're right ;)

Most Ms from 92 onwards will have drainage holes (there were some frankenstein boards from 92 that have drainage channels but no holes in the cases, or vice versa)

However, since this is a French layout one, it was likely made in Greenock, and therefore will not have the drainage channels on the keyboard assembly, but will have holes in the case. This may affect its drainage abilities...

@John Boone - looks like you've done a good job. My initial reaction when I read your post was that there was some liquid damage that was shorting out the membrane. You should be good to go now... the controller electronics tend to be pretty sturdy, it's almost always the membrane that's the point of failure...
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: John Boone on Wed, 02 May 2012, 14:15:32: Quote from: ch_123;588137
However, since this is a French layout one, it was likely made in Greenock, and therefore will not have the drainage channels on the keyboard assembly, but will have holes in the case. This may affect its drainage abilities...
Bingo ! It has holes but no drainage channels. I didn't reply earlier because I didn't know how were those channels, until I find this photo on another thread :
http://www.shrani.si/f/3O/hz/2tGbPib6/lexmarkboard.jpg

BTW, this is great idea to have holes to evacuate liquids, however I don't understand why the black plastic part has some tiny holes on the top. It will let the liquid to enter inside.

Quote from: ch_123;588137
@John Boone - looks like you've done a good job. My initial reaction when I read your post was that there was some liquid damage that was shorting out the membrane. You should be good to go now... the controller electronics tend to be pretty sturdy, it's almost always the membrane that's the point of failure...

Those membranes look a little vulnerable and thin. I don't know how many years left they have. However this is simply an impression, and may be it can still last 20 years. :)
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: fohat.digs on Wed, 02 May 2012, 15:53:14: Those membranes are "fragile" because they were never intended to "see the light of day" - the melted rivet tops were clearly never meant to be broken apart.

We are just lucky that there is a remedy such as bolt-modding available to us!
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: 486 on Wed, 02 May 2012, 16:15:03: Quote
Most Ms from 92 onwards will have drainage holes (there were some frankenstein boards from 92 that have drainage channels but no holes in the cases, or vice versa)

I don't know much about this model so I just made an assumption. Since you are bolt modding, the hardest thing I found with parts is finding th 4mm socket. I was easily able to find all the other parts but it took about 10 different hardware stores to find that socket. The internet may be a better option but I don't know what hardware stores are available to you. Hopefully, you have one already.
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: John Boone on Sun, 13 May 2012, 11:43:38: [ATTACH=CONFIG]50143[/ATTACH]
Prior to do the re-assembly, as i said there are a few holes on this part, liquids will love to use them to spill inside !! I used some glue to fill them, and for the 2 holes for the space bar driver I used some black rubber + glue.

Here is my alternative "thumbtacks" method instead of bolts:

[ATTACH=CONFIG]50141[/ATTACH]

Only 6 screws in the middle. It was enough to ploy the black plastic cover, then insert the thumbtacks to make everything tight.
But before, you have to drill a tiny hole with a mini-dremel in the center of each rivet body. The pins need to be cut to 4mm.

Just add a very slight amount of neoprene glue on each hole before inserting so that the thumbtacks don't drift with time and hold permanently.

[ATTACH=CONFIG]50142[/ATTACH]
With a little saw for metals you can make the screws more "friendly".

[ATTACH=CONFIG]50144[/ATTACH]
I am lucky, now the keyboard is perfectly functional and I can enjoy the sound and the feeling of the buckling springs !
Title: Restauring an old Model M (1391402 FRENCH) - Alternative thumbtacks mod
Post by: N8N on Sun, 13 May 2012, 11:51:34: Looks good, now you just have to find those missing keycaps - good news is they look the same as the US English ones so you shouldn't have a big problem with that. Let us know how it holds up over time compared to a traditional bolt mod.