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Author Topic: Model M2 Repair  (Read 2338 times)

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Offline TheSven

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Model M2 Repair
« on: Sun, 14 December 2014, 15:26:50 »
I've got my IBM Model M2 here with bad caps. I would have asked these questions here: https://geekhack.org/index.php?topic=5065.0 but it wouldn't let me post. Will be ordering some soldering gear and new caps tomorrow. I have a few questions about the fix. I will just let you no that I have had 5 mins worth of soldering practice.
First question: How exactly do you replace the caps? Could someone who has done it give step by step guide on youTube or something please. I don't understand how to remove the capacitors. Do I need to take out the PCB or what?
Second question: What kind of a iron tip would be needed? Does a fine one need to be used?
Third question: How exactly does the case come apart? There's screws on the back and tabs on the case I assume?
Fourth and final question: How do the springs go back in? You remove the keycaps before disasembly I believe, so the springs go in the holes on the top part of the case and then the mat, membrane and PCB is laid on top and snapped together.
Sorry for such a long post, but I really needed to know. Thank you.
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Offline fohat.digs

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Re: Model M2 Repair
« Reply #1 on: Sun, 14 December 2014, 16:52:39 »
Quote from: TheSven on Sun, 14 December 2014, 15:26:50

First question: How exactly do you replace the caps?  I don't understand how to remove the capacitors. Do I need to take out the PCB or what?

Second question: What kind of a iron tip would be needed? Does a fine one need to be used?

Third question: How exactly does the case come apart? There's screws on the back and tabs on the case I assume?

Fourth and final question: How do the springs go back in?


These are partial answers, until the good ones come along. I have never done this particular repair so I don't really know anything.

(1) You will need to heat up the existing solder to get them out. If you don't have a solder sucker or wick, you should probably get one.
(2) A pointed tip may be better than a wedge, here.
(3) You probably unscrew the back and pop the front apart like a book. It has been a long time since I had my hands on an M2, it would be nice if you did not have to take it completely apart.
(4) Do what he says for the capacitors.
« Last Edit: Mon, 15 December 2014, 12:07:05 by fohat.digs »
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Offline arakula

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Re: Model M2 Repair
« Reply #2 on: Mon, 15 December 2014, 00:52:55 »
Disassemble / reassemble: http://www.instructables.com/id/Clean-your-vintage-IBM-M2-clicky-keyboard/

I'd advise against heating up the controller board while it's in place. The matrix foils run directly below it and could easily be destroyed.
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Offline TheSven

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Re: Model M2 Repair
« Reply #3 on: Mon, 15 December 2014, 02:25:40 »
Quote from: arakula on Mon, 15 December 2014, 00:52:55
Disassemble / reassemble: http://www.instructables.com/id/Clean-your-vintage-IBM-M2-clicky-keyboard/

I'd advise against heating up the controller board while it's in place. The matrix foils run directly below it and could easily be destroyed.
So do I desolder from the bottom of the PCB? Hold the iron against the bottom of the cap and pull it from the other side?
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Offline arakula

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Re: Model M2 Repair
« Reply #4 on: Mon, 15 December 2014, 03:05:55 »
Quote from: TheSven on Mon, 15 December 2014, 02:25:40
So do I desolder from the bottom of the PCB? Hold the iron against the bottom of the cap and pull it from the other side?
No. But please keep in mind that this soldering iron has a temperature that's rather high - FAR higher than the melting point of the plastic foils that are directly below the controller board. If you heat up the solder joint to something in excess of 300 °C, the heat doesn't stay in place; the bottom of the board is heated up as well.
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Offline TheSven

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Re: Model M2 Repair
« Reply #5 on: Mon, 15 December 2014, 10:23:08 »
Quote from: arakula on Mon, 15 December 2014, 03:05:55
No. But please keep in mind that this soldering iron has a temperature that's rather high - FAR higher than the melting point of the plastic foils that are directly below the controller board. If you heat up the solder joint to something in excess of 300 °C, the heat doesn't stay in place; the bottom of the board is heated up as well.
How exactly do I desolder then? Just hold the iron on the cap and pull it off?
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Offline Touch_It

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Re: Model M2 Repair
« Reply #6 on: Mon, 15 December 2014, 11:04:26 »
Speaking from experience about dis-assembly (typing this on my M2)  after taking keycaps off and removing the screws the thing is still held in place by plastic brackets.  Each time I've taken mine apart it required a bit of force or maneuvering witch caused springs to fly everywhere.  Maybe I was doing something wrong but at least you are prepared.  As far as the pcb I cant speak about soldering but it is kind of tricky to get it out as there are 4 or 5 plastic tabs holding it in place.  I took mine out and put it back in but I broke 2 of the tabs, but it doesn't seem to affect anything.  At any rate hopefully I made sense and this helps.  I really do like my M2, it is a lot of fun to type on, and makes a lovely pinging noise.  I would check the membrane for any bad traces with a multimeter or continuity tester when apart if possible as mine had a bad section and i needed to retrace it for all my keys to work. 
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Offline TheSven

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Re: Model M2 Repair
« Reply #7 on: Mon, 15 December 2014, 17:05:36 »
I think I've figured out how to remove the caps after watching some YouTube videos. Thank you people of GH!
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Offline Touch_It

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Re: Model M2 Repair
« Reply #8 on: Mon, 15 December 2014, 20:51:11 »
Good luck.  I seem to have gotten very lucky as mine still has the original caps from 1990.  Once you get yours working let me know how you like it.  I find the feel a fair amount different from a model m.
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