IBM model M problem

[number7]

I have a IBM model m 1391401 that is giving me problems:

1. it keeps repeating random keys upon boot and making the PC speaker click. also on login it multiplies the key like passwordddddddddddddd or passwor8d
2. it does this with a USB dongle or ps2 plugged in directly.
3. keyboard is super clean- keys are not sticky and I cleaned the keys recently, and do not have heavy fingers.

anything I can do to fix this?  Do I need a new PCB, if so where?

[MMB]

You would most likely need to replace the controller. The keyboard itself uses a membrane sandwiched in between a layer of plastic and a layer of metal.
The controller is pretty much all that could be causing that, unless the membrane or keyboard itself was damaged.

But you can just buy another one pretty cheap. Might be easier than trying to find a separate controller
http://www.ebay.com/sch/i.html?_nkw=ibm+model+m

[number7]

Ya, I am just trying to save the huge shipping cost to Canada.

And its a white label and I really like it over my blue.

its weird that given the huge interest in mechanical keyboards that a wireless or USB PCB swap out isn't available.

[wcass]

it sounds to me like there is conducting moisture between the membrane sheets. if that is the case, follow the directions for a bolt mod, but take the sheets out and rinse them with clean water (no scrubbing) and let it air out till completely dry before finishing the bolt mod.

[number7]

it has been humid here and raining all the time....

[wcass]

if you want to check if it is controller or membrane, disconnect the membrane. you will have 2 or 3 membrane connectors - one is 16 conductor and there will ether be an 8 and a 4 or a single 12 conductor connector. the 16 is the matrix columns and the 8 closest to the 16 to the columns is the rows (the last 4 are for LEDs).

randomly short single columns with single rows. some of these connections will be "not defined" - but you should not get any repeating (unless you hold the short).

[dorkvader]

If it's the membranes, you can probably get a replacement from unicomp, or I believe you can also repair it with a conducive pen.

[number7]

I took it apart yesterday- wow does 24 yrs of use look gross. I cleaned everything including pulling out the connections to the board- which were dirty and black, put it back together and now it works perfect.

I am relieved, I took a look at the new "mechanical" keyboards out there and was not impressed- letters wearing off (corvair) inconsistent feel with other cherry based products.  They just had no bounce and were all too quiet.

Thanks a lot guys for throwing all those suggestions out there!!!!

[ch_123]

Almost certainly a membrane failure, controller issues are pretty rare with the regular Model Ms.

There are guides around here. The basic idea is that you have to get a silver conductive gel pen, and use it to repair the affected traces. Afterwards, you'll need to do a bolt mod (plenty of guides on here as to what this involves, and how to do it)