Tandy TRS-80 Model 4

[Bryan Pope]

Michael B. Brutman wrote:
>
> I had tried abrading the surface a little bit with that thought in 
> mind, but it did not help at all.  I also measured the resistance of 
> the black disc using the meter probes touching it directly (with a 
> little force), and the resistance was high as expected.  (Somebody had 
> suggested that the disc was conductive, but after that test I doubt it.)
>
> I think the best idea at the moment is the conductive ink used to fix 
> circuit board traces.  I'm going to give that a shot - there is a trip 
> to Rat Shack in my near future.
>
> It's exciting to think I might get this machine running well again.  
> The keyboard has been a big hangup for me.  I don't mind fixing a few 
> keys on this new keyboard, but tearing up all of the keys on the last 
> keyboard was too much to fathom.  After it's running I'm going to be 
> in sponge mode for a while, and then I'm going to try to setup a 
> development environment - I think this machine needs a TCP/IP stack. :-)

Mike,

    Has anyone mentioned using a pink eraser to clean the surfaces?  I 
have used that to restore keys on a PET that had become unresponsive.  
The problem keys had a "shine" on the black conductive rubber matching 
the shape of PCB traces they were hitting.  The pink eraser removed this 
shine and the keyboard worked like new afterwards.  Just make sure to 
get rid of any eraser leavings!

Cheers,

Bryan