Dead Column On Model M Membrane

[koalapear]

Hello! I am currently in the process of bolt modding my two full sized Model Ms but I have run into a snag. The '87 model appears to have a dead column on the membrane and I have to idea why. The column in question is the one responsible for "9","0","p","[",";","'", and "/". I have tried the membrane assembly from the '91 with the controller from the '87 and it works flawlessly. I have also checked the continuity between the pads and the contact at the top where the membrane plugs into the controller and there is none. However, there is no visible damage to the trace at all. Any ideas as to what could be causing this or how to fix it? I'm guessing a new membrane assembly from Unicomp is my best bet at this point but I would love if I could keep it all original! Thanks!

[Catfish]

I made a thread a while ago about this, i could not get a new unicomp membrane to work with a circa 1991 chipboard.It did however work fine with a 1993 board so maybe they changed the electronics when they rebranded to lexmark.Also i could not get unicomp to send me out a new pcb on its own to go with the new membrane they would not reply to my requests on that.

[koalapear]

Thanks for letting me know. I guess I'll have to try and source a new one from the correct era. Looks like I won't be getting this board up and running for a while...

[Daniel Beardsmore]

You should be able to repair the membrane trace if you can isolate the break in it.

[koalapear]

Well I found that the break is somewhere in the ribbon cable section where all if the traces converge and go to the pads that make contact with the connector on the controller. I picked up a CircuitWriter pen at Radio Shack and used that to draw a new trace. It's drying right now but hopefully that does the trick.

[ezrahilyer]

Well I found that the break is somewhere in the ribbon cable section where all if the traces converge and go to the pads that make contact with the connector on the controller. I picked up a CircuitWriter pen at Radio Shack and used that to draw a new trace. It's drying right now but hopefully that does the trick.

I use this 1.8" copper foil tape to repair traces, it works very very well, and doesn't leave a mess or flake off over time.
http://www.amazon.com/gp/product/B00EY44I42/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00EY44I42&linkCode=as2&tag=strapoet-20&linkId=SHM6U4XQZJJGREWY

Most likely the circuit writer will work for you, but I have had some trouble myself with keeping the traces where I want them.

[koalapear]

I use this 1.8" copper foil tape to repair traces, it works very very well, and doesn't leave a mess or flake off over time.
http://www.amazon.com/gp/product/B00EY44I42/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00EY44I42&linkCode=as2&tag=strapoet-20&linkId=SHM6U4XQZJJGREWY

Most likely the circuit writer will work for you, but I have had some trouble myself with keeping the traces where I want them.

It looks like my attempt with the CircuitWriter was indeed successful! Definitely not my favorite stuff to work with though so I much appreciate the tip on the copper tape! If I have any flaking problems in the future it will be my next go to.

[ezrahilyer]

[/quote]

It looks like my attempt with the CircuitWriter was indeed successful! Definitely not my favorite stuff to work with though so I much appreciate the tip on the copper tape! If I have any flaking problems in the future it will be my next go to.
[/quote]

if you ever need a little bit of the stuff just shoot me a PM, I would be happy to drop some in an envelope and mail it to you, since it doesn't usually take much.
I would be happy to donate the stamp. lol

BTW, that also goes for any other members here, if you want some of this tape, you don't have to order a whole roll to get a little bit, just PM me and i will send you a foot or two for free.

-Ezra

[koalapear]

if you ever need a little bit of the stuff just shoot me a PM, I would be happy to drop some in an envelope and mail it to you, since it doesn't usually take much.
I would be happy to donate the stamp. lol

BTW, that also goes for any other members here, if you want some of this tape, you don't have to order a whole roll to get a little bit, just PM me and i will send you a foot or two for free.

-Ezra

Thanks man! I really appreciate it!!

[dorkvader]

you can sometimes just cut the membrane edge connector past the break and plug it in really carefully to the controller, depends on where the break is.