Unicomp Dead Cluster of Keys - Bolt mod advice needed!

[eggbert]

Hi All,

I have a Unicomp "Customizer"  model M from around 2010 or so.   It lasted a couple years, and then  a cluster of keys stopped working  (4, 5, r, t, f, g, v, b).  I opened it up and tried to clean the contacts on the controller board and membrane connectors with some alcohol, but no luck.   So I stuck it in my closet and moved on with life.  However, the Model M bug has bitten me once again, so I'm going to try and resurrect my old Unicomp.   I have a few questions:

1. Before I go balls out and try to do the bolt mod,   Is there anything else I can try to get that cluster of keys working again?  I'd really like to avoid bolt modding if possible.   I read somewhere about giving the barrel frame assembly a bath in distilled water.   This seems crazy to me though.  If it's a broken trace on the membrane, that wouldn't fix anything.

2. Nut & Bolt Mod:  I have all the tools and screws I need according to this guide: http://wiki.geekhack.org/index.php?title=Modifications:IBM_Model_M:Nut_and_Bolt_Mod   However, I notice on the Unicomp that the plastic rivets around the edges of the assembly are VERY close to the edge of the plastic barrel frame.  There appears to be zero room for error, and drilling holes there would possibly end up cracking the plastic.  What should I do here? 

Any thoughts or ideas would be appreciated!

[E TwentyNine]

Does that model have the center controller or the one over the numpad?

Either way, your problem is a trace and a bolt mod won't do squat.   All those keys are on the same trace - the 6th one on the major connector on a center controller style.  As it's high up, there's a good chance the break is up near where the trace exists from under the barrel plate.

You'll want to take a close look there.  It can be repaired by conductive tape, a piece of fine wire and something like scotch tape, or even simply conductive glue.

[fohat.digs]

the plastic rivets around the edges of the assembly are VERY close to the edge of the plastic barrel frame. 

You can use thinner or shorter screws, possibly self-tapping ones at the edge. If you want to use nuts you will have to clip off the ridges on the top side.

[eggbert]

Does that model have the center controller or the one over the numpad?

Either way, your problem is a trace and a bolt mod won't do squat.   All those keys are on the same trace - the 6th one on the major connector on a center controller style.  As it's high up, there's a good chance the break is up near where the trace exists from under the barrel plate.

You'll want to take a close look there.  It can be repaired by conductive tape, a piece of fine wire and something like scotch tape, or even simply conductive glue.

Controller is over the numpad.  But you were right it's a trace!  I took a closer look at the traces that go around the edge of the keyboard (The membrane & traces are exposed there) and I noticed a spot that looked like it was broken, right where the membrane goes under the plastic.    I poked the end of a guitar string through the membrane there to try and jump the broken trace and it worked! The keys started working! 

Now my dilemma is how to fix this broken trace properly without having to bust the plastic rivets.    The guitar string kind of works, but I think over time it's going to get dislodged... It's kind of precarious, if it's not situated just right the keys stop working...

[E TwentyNine]

"Proper fix" is a state of mind.   If you get some fine wire (like a strand or two out of multistrand wire) and scotch tape it will hold for a lot longer than you think.

You may have to repair it again in six months or a year, but you'll know what to do and it'll be a 15 minute job.   A lot easier than a bolt mod and buying a new membrane.

The conductive glue (with fine wire) or conductive tape approach will give you a more permanent fix, but if it works with the simple fix, run with it.

[eggbert]

Well,  it's not pretty but I think I came up with a pretty reliable fix.  I took a piece of guitar string and superglued it to a thin piece of cardboard and slid it under the broken trace.  Seems to be holding pretty firm and I won't have to worry about the wire moving around in there.    Just need to tape it down.



So all keys are working and I am pretty happy.  Thanks for the tip!   

Only bummer is that I had already ordered the screws and a new membrane from unicomp.  Oh well - at least I'll have that stuff if I ever need to do a bolt mod

[Wingklip]

Sometimes the model m has a common issue of improper actuation, where the plastic front panel warps a bit and causes the flippers to slightly displace. This may still allow it to ping, but the flippers get stuck. Perhaps this is the cause of the issue?

Look for any cracks in the front panel plate