Problem with Model M after bolt mod -- stuck/repeating spacebar

[intelli78]

I have a Model M that was recently bolt modded (not by me). All keys work except the spacebar; when plugged in, the keyboard constantly registers spacebar input, as if the key is stuck.

Observations:

- It only happens when there's a key inserted on the stem. If there is no key, there are no keypresses registered.

- If I place a keycap and push on the cap sideways, it stops repeating. Then I can jiggle the key to toggle spacebar presses one at a time.

- The assembly clicks properly, it sounds and feels like all other keys.

- The angle of the spring appears different than most others. Most others are angled up toward the 12 'o-clock position; this one sticks pretty much straight up in the center of the barrel.

- When I pull a keycap, or just tap the spring with the tip of a pen, the spring vibrates like crazy, MUCH more than any other spring on the board. It vibrates so fast it's blurred, whereas other springs just bounce a tiny bit and then stop. This seems to suggest a mechanical problem as opposed to an electrical problem with the contact sheet, etc.

Here is a comparison photo. On the left is a working assembly, on the right is the non-working spacebar assembly. I cannot discern any visible problem from this photo, other than possibly the unusual angle at which the spring is projecting, but perhaps it'll be helpful to someone more knowledgeable.



Anyone have an idea what's going on, and how I might repair this?

[FreeCopy]

It might be that the screw closest to it is too tight. Might try making adjustments around it.

[Melvang]

Almost sounds like the foot got out of place during the reassembly.

[intelli78]

Another observation: if I shake the board, other springs move around freely, but this one stays stationary without flopping around, as if it is being held tightly in place.

[Snowdog993]

Your hammer has slipped out of the slot it's supposed to sit in.  The screw was tightened down but only after the hammer has slipped.  You might have to do a teardown and reseat the hammer back in place.  (If the hammer won't slip out again.)  This looks like the problem to me.  I've tried a bolt mod myself and failed at it.  I won't lie.  It's not easy to do.

[Snowdog993]

Almost sounds like the foot got out of place during the reassembly.

+1
That's exactly what happened.

[intelli78]

Thanks for the info guys, makes sense...

Anyone ever been able to 'massage' a hammer back into place from the top of the barrel, without a total disassembly? I did some research and at least one post on GH mentions doing it with needlenose pliers...

Edit: yes, the hammer/foot is definitely pinched somehow, unable to move. I poked at it gently, but it doesn't want to free itself. It may already be damaged from being pinched in there, hard to tell.

[infiniti]

Thanks for the info guys, makes sense...

Anyone ever been able to 'massage' a hammer back into place from the top of the barrel, without a total disassembly? I did some research and at least one post on GH mentions doing it with needlenose pliers...

Edit: yes, the hammer/foot is definitely pinched somehow, unable to move. I poked at it gently, but it doesn't want to free itself. It may already be damaged from being pinched in there, hard to tell.

PLEASE DO NOT TRY TO PRY THE BARREL PLATE AWAY AND BANG ON THE ASSEMBLY...YOU WILL ONLY DISLODGE MORE HAMMERS.

I was able to reposition without complete disassembly by but I was lucky that it was on the Num Pad and I only undid enough bolts to gently pry the barrel plate away enough to make space to move the hammer in place.

I held the assembly with the barrels facing down, pried the edge of the barrel plate and inserted some plastic spacers keep the gap open (I used some plastic utensils I had lying around), look down the barrel with a flash light. and then with tweezers grab the spring and reposition the hammer properly.  It took me a while but it saved me from disassembling the whole thing.

[pr0ximity]

When I  bolt-modded mine I had a very similar thing happen to my spacebar. Unfortunately I can't tell you much more than that reassembly fixed it. In my case I attributed it to the blanket bunching up a bit because at first I didn't bolt the very bottom row so there was nothing holding that edge of the blanket firmly in place. Disassembled it, added that row of bolts, and it corrected it. Could have just been the reassembly in general though.

Regardless as others have said, if the spring doesn't wiggle freely then the hammer is stuck due to misalignment or something else.

Moving the hammer without disassembly would be very difficult I'd think. I suppose if you chopstick'd the spring off you might be able to nidge the hammer laterally with something (a chopstick). Loosen the bolts around the bar slightly and see if you can shift the hammer, but if it's far off you're going to have a bad time, and if it doesn't look mis-aligned the blanket may not be sitting evenly towards the base of the board if there are no bottom-row bolts.

In complete honesty, it's not all that big of a pain to take it apart if it's bolt modded. You'll likely spend way more time doing things that may misalign other hammers if you try and do it closed. Prop both sides on books or something, take the caps off, open it with the springs facing down, and you should be able to gently lift the plate and blanket off and then just put it back together. It only becomes a pain when you have to do it multiple times in a row because it helps to do it patiently. But you won't break anything unless you're a ham-fisted brute.

[berserkfan]

Thanks for the info guys, makes sense...

Anyone ever been able to 'massage' a hammer back into place from the top of the barrel, without a total disassembly? I did some research and at least one post on GH mentions doing it with needlenose pliers...

Edit: yes, the hammer/foot is definitely pinched somehow, unable to move. I poked at it gently, but it doesn't want to free itself. It may already be damaged from being pinched in there, hard to tell.

This should be an easy, if time consuming fix.

Take apart the whole thing.

While doing so, wipe down the membrane with some alcohol swabs 'just in case'.

Put it back together, while keeping your eyes on the hammers just to make sure there is no little bit of debris stuck to a hammer bottom.

The problem should go away by itself.

Downside? Takes over an hour to do this.

I DEFINITELY DO NOT AGREE WITH HAMMERING OR BANGING ON THE KEYBOARD IN HOPES THAT THE HAMMER WILL MAGICALLY BE CORRECTED.

[intelli78]

Update:

I took the case off and loosened the screws nearest to the spacebar, which allowed more play between the barrel plate and the other layers. I was able to move the hammer around this way, but it did not settle in place, and was now obviously out of place.

So, I fully disassembled it, reseated the hammer  (it looked fine but I swapped it with the Pause hammer just in case).  Replaced a few screws, then plugged in to test before doing them all.

No change. When plugged in, space kept repeating. AND, the spring and hammer still seemed really stiff compared to all the others on the board, as if still somehow pinched.

I loosened the screw nearest the spacebar a little, which made it stop repeating, but now it required bottoming out completely to register. Tightened a little, and then it was working right. Seemed really finicky especially considering all other keys worked fine.

Reassembled fully. Plugged in. ..and now, nothing!

If I take the board out of the case and squeeze the barrel plate against the metal right next to the space bar barrel,  it registers key presses from that action alone. But pressing the key does nothing.

I'm not sure what to make of this.

The parts appear to check out, but for some reason the hammer in the space bar position doesn't move as freely as all the others and even when I sort of got the switch working, it was abnormally sensitive to the tightness of the nearest screw.

So...something is not right. Maybe that barrel is slightly warped and is affecting hammers installed in the spacebar position,  or maybe there's something wrong with one of the membrane sheets? I'm not sure, but it's not obvious.

Also, now I don't even think that hammer WAS out of place to begin with, since it's behaving the same way physically, when it is seated correctly. (The spring sticks straight out, and does not flop back and forth like the others when the board is tipped away/toward you.) If this is all stemming from a hammer problem,  it's due to something less obvious than an out-of-place hammer.

[berserkfan]

Oh svvv

I feel awful for having suggested this to you. It did work for me (although I never found any debris or anything affecting the contacts).

Your face must be looking something like your avatar now?

Suggest checking with fohat or dorkvader.

[FreeCopy]

I wish I could get it to my house. I want to go over out of pure curiosity and hopefully learn something. Worst case it doesn't work and/or I cause more problems and you can have one of mine.

[intelli78]

Hey guys, I don't blame either of you at all, I think your suggestions were spot-on given the information. I was very surprised when I put it back together and it was still not working.

I will try pinging those two.

[Snowdog993]

If it is sitting properly, it should be just like the rest.  There is really something wrong.  Possibly the geometry of the backplate to the barrel assembly, or a gap just wide enough to make that hammer slip out of place.  It's a real pain like I said before.  Can the person that did this fix it properly for you?  I really hope they can.

[intelli78]

If it is sitting properly, it should be just like the rest.  There is really something wrong.  Possibly the geometry of the backplate to the barrel assembly, or a gap just wide enough to make that hammer slip out of place.  It's a real pain like I said before.  Can the person that did this fix it properly for you?  I really hope they can.

Yeah, I think it must be something subtle like that. Yes, spoke to the seller to see if he had any ideas, and he told me he'd just exhange the inner assembly and try to fix it himself. I'll post any updates I get, and also will post more about the board itself once I get it up and running with the new internals.

[fohat.digs]

My first recommendation would be to examine the underside of the barrel plate (perhaps with a magnifying glass) to look for damage or scraps of excess plastic floating around. There is something preventing the pivot plate from pivoting properly.

Look to see if there is a shard spiralling out from where the hole was drilled, or a little chunk wedged into a corner. If you can seat the pivot plate with the internal parts open, reach your hands around and try to wiggle it from both sides.

There is also the possibility that there is a bit missing from the seat socket of the barrel such that the pivot plate can shift. Those "ears" of the pivot plate need to be held in their slots properly, but still move freely.

I have experienced similar (but not nearly so bad) problems with over-tightened bolts. Remember that you now have dozens of steel bolts replacing mere blobs of plastic - they do not need to be cranked down hard.

Because of a ridge in the plastic at the front, below the spacebar, some people cut the rivets off but do not re-bolt the bottom edge. There are stresses there by the way the frame clips into the case, so that row does need to be fastened somehow. At first, the recommendation was to use small self-tapping screws, or clipping out sections of the ridge to make room for the nuts.

Nowadays, many modders are leaving out the nuts altogether anyway, so you can use that method to and take that row up through the bottom plate and into the plastic, without nuts.

Finally, and be very careful if you try this, I have occasionally been able to to shift a pivot plate by a millimeter or so to re-seat it, in an assembled keyboard, by sticking a tiny awl down onto the top of the foot of the pivot plate, and scooting it a hair's breadth laterally while applying pressure straight down.

[intelli78]

My first recommendation would be to examine the underside of the barrel plate (perhaps with a magnifying glass) to look for damage or scraps of excess plastic floating around. There is something preventing the pivot plate from pivoting properly.

Look to see if there is a shard spiralling out from where the hole was drilled, or a little chunk wedged into a corner. If you can seat the pivot plate with the internal parts open, reach your hands around and try to wiggle it from both sides.

There is also the possibility that there is a bit missing from the seat socket of the barrel such that the pivot plate can shift. Those "ears" of the pivot plate need to be held in their slots properly, but still move freely.

I have experienced similar (but not nearly so bad) problems with over-tightened bolts. Remember that you now have dozens of steel bolts replacing mere blobs of plastic - they do not need to be cranked down hard.

Because of a ridge in the plastic at the front, below the spacebar, some people cut the rivets off but do not re-bolt the bottom edge. There are stresses there by the way the frame clips into the case, so that row does need to be fastened somehow. At first, the recommendation was to use small self-tapping screws, or clipping out sections of the ridge to make room for the nuts.

Nowadays, many modders are leaving out the nuts altogether anyway, so you can use that method to and take that row up through the bottom plate and into the plastic, without nuts.

Finally, and be very careful if you try this, I have occasionally been able to to shift a pivot plate by a millimeter or so to re-seat it, in an assembled keyboard, by sticking a tiny awl down onto the top of the foot of the pivot plate, and scooting it a hair's breadth laterally while applying pressure straight down.

Many thanks for the reply-- good ideas here. The seller offered to swap out the internals for me, so I took him up on the offer. But he's going to attempt to fix, so I will pass this along to him.