Some keys on a IBM Model M keyboard aren't working

[nick_90]

Hey guys. This is my first post.

I brought a IBM Model M keyboard (Model 1391401 Dated 11-05-91) from eBay. So far I had it for a week, working flawlessly and was really enjoying using this keyboard.

Now today I turned on my PC and was using my keyboard and I noticed that my spacebar isn't working all of a sudden, which I thought was really strange and then I realised my B and N keys aren't working ether, so aren't the arrow keys (expect for the up button) and my question mark key. All of the other keys seem to work fine expect for the ones I mention. I tried in on another PC and got the same result.

I have opened up the keyboard and reseat the ribbon cables but I still get the same result.

So could anyone tell me is there anything else that I can try or is my Model M screwed and I should be looking for another one. Moreover, after using my model m, I now despise using a rubber dome keyboard lol.

Regards,
Nick

[E TwentyNine]

Those keys are all along the same trace.

If the numpad minus key works, there's a problem between it and the right arrow key and you'll have to open the keyboard up to repair/replace the membrane and do a bolt mod (or return it to the seller).

If the numpad minus key fails, there's a problem on the trace above it.

If that's the case, take a look at the connections, specifically the small ribbon with 8 leads.  Pay attention to the lead on the far right, that's the one with the problem, make sure it's getting good contact.

[nick_90]

Thanks for getting back to me.

I opened up the keyboard and looks at the membrane and it turned out that someone had split something along the side and it damage some of the trace. However I was able to get some Silver Conductive Varnish from my electronics store and was able to repair that trace.

Now another problem has arise, I am trying to put the keyboard back together. And I'm testing the keys out. They all work when I tap over the mat but as soon as I place the plastic barrel plate and put some keys on top, the keyboard doesn't respond to any keys what I press unless I jiggle with the spring. Do I need to do the bolt on method in order to get my keys to work again. Sorry if I'm sounding like a noob, I never repaired a keyboard in my life.

Regards,

[E TwentyNine]

If you separated the barrel plate from the back metal plate you're going to need to do a bolt mod.  Search on here for "bolt mod", it's a straightforward process just a little monotonous.