Repairing a model M.

[dos]

Heyo,
So the other day I spilt tea on my model M.
It still worked albiet poorly. Keys directly under the spill only worked sporadically.
I took it apart, cleaned and dried it as best I could, and after putting it back together, to my horror it stopped working.
The lock lights still flash during POST but there is no response at all from any key.
Have I broken the controller?

[chzel]

I suppose you did not separate the plates to clean the menbranes, so it might be shorting in a couple of places. Did the controller get wet? Did you use any liquid to clean it?

[dos]

Yeah I didn't seperate the plates.
I used isopropal alcohol to clean what I could and then left the plates under a fan for a night to try and dry it.

[Mal-2]

The lock lights still flash during POST but there is no response at all from any key.
Have I broken the controller?

Probably not.

First thing I'd look at is whether there is a misalignment between one or both membrane layers and the controller. After that I'd look at misalignment between the membrane layers themselves. Then I'd wonder about there being adequate force between the membrane edges and the contacts on the controller, and whether those are clean. (Inadequate force and dirty contacts usually manifest as some keys working and others not, though. Not 100% failure.)

(Got ninja'd.) Oh you didn't take it apart that far and might have liquid in the gap? That changes everything. It's still unlikely you bricked the controller though.

[dos]

Should I take the plates apart?
It worked after the spill untill I took it apart.

I'm hesitant to take the plates apart and have to bolt mod it.

[dos]

I've just reassembled it again and most keys work while a few dont. Could it just be the alignment of the membrane layers and the controller??

[chzel]

Most likely you will have to open it, if you had spilled clean water you might get away with it, but tea will leave residue behind, and mess with everything. Also a night is probably not long enough for the membranes to thoroughly dry out.
I'd say give it a couple of days in a warm environment and if it does not work, get inside! This is assuming that the tea was plain, no sugar or milk or whatever!
An alternative to parting the plates might be a good soak with IPA, but I am not sure how the membranes will like it...

PS: Welcome!

PS2: If you didn't part the plates, the membranes are unlikely to have shifted.

[dos]

Thank you thank you!

[dos]

So I've dropped a little isopropal alcohol down the barrels of the faulty keys. Its a long shot. Hopefully tomorrow they work. If not bolt mod.

[dos]

Anyone have a suggestion for a good bolt modding guide?

[chzel]

One of the best

[fohat]

If you put sugar in the tea, it may be a big problem.

Otherwise, I would recommend a drying time of 48 hours or more outside in the breeze, or 72 hours minimum indoors.

[idollar]

So I've dropped a little isopropal alcohol down the barrels of the faulty keys. Its a long shot. Hopefully tomorrow they work. If not bolt mod.

I have cleaned 3 or 4 key boards that were spilled. I have seen the membranes after the incident.
My recommendation is to open it and clean the complete lot.

The risk is that in the medium run they get broken. You can see the consequences in this thread. An example of a broken membrane follows:

[dos]

Thanks everyone for your help.
I took it apart and cleaned it. The membrane is broken.
Before cleaning, keys D, B, N and Space didn't work. Now only B and N don't.
Here's some multimeter-less testing:

IMAG0618.jpg (601.08 KiB) Viewed 2415 times

As B and N don't work, I'm guessing the membrane is broken here:

IMAG0619.jpg (537.11 KiB) Viewed 2415 times

Hopefully the conductive ink does the trick.

[Touch_It]

my 1 experience with conductive ink worked well. Someone gave me the tip of using a paper clip to apply it so it wouldn't get too thick. Worked pretty well.

[eldorange]

How do you remove and put back in place those LED lights in the membrane?

[LLRnR]

How do you remove and put back in place those LED lights in the membrane?

Take a look at this picture.

IMG_3655.JPG (165.75 KiB) Viewed 2374 times

The LEDs are placed on a small circuit board with a layer of foam underneath. On the membrane, there are guidelines in the corners of the area where the LED board should go (see the white guidelines in the picture). You would want to remove the LED board, I suppose, if you plan to replace one of the LEDs or if you want to move the whole LED board to a spare membrane. You would of course have to unplug the ribbon from the connector (J1) first. Other Model Ms (like my 1390130) have a more standard cable (not a ribbon, but using yellow wires instead). I never had to do this myself, but I guess you'd just have to carefully detach the foam from the membrane and carefully glue it back in place afterwards. The placement of the LED board does not overlap an actual circuit on the membrane, so it should be fairly easy.