Successful repair of Mitsumi carbon pad Keyboard

[Imperious]

1st of all many apologies for the lack of photos as I did not expect this to work.

 

I recently purchased 3 TI's from ebay, 2 beige consoles and 1 silver/black unit. To my amazement they all worked and both beige consoles

have the 1981 Roms which was a relief. One of the beige units is immaculate and doubt it was ever used, the other one was all good except

the only key that worked was the "1" key, which was a pain in the butt as I couldn't get even a cart to run.

 

This one fortunately is the only one with the crappy mitsumi keyboard, the others have the more heavy duty looking soldered pcb.

 

Today I thought I would take a second look at it.

 

After removing all the screws and desoldering the Alpha lock key the board can be carefully lifted off away from the actual key section.

Next I even more carefully peeled the carbon plastic sheet off taking extra care around where the tracks on the carbon sheet and pcb meet up.

That didn't go as well as I had hoped with some bits breaking off. Closer inspection revealed it wasn't as bad as it could have been.

I was going to try and re-write the tracks with my conductive pen but that was dried out and useless. Then I remembered that years ago

I successfully unlocked multiplier adjustents on my AMD Duron processor by joining the bridges with carbon from a Pencil.

 

1st I cleaned all carbon pads on the plastic sheet with a cotton tip and methylated spirits applying as little pressure as possible, then I got

a HB pencil, sharpened it, then kept on drawing on the pads on both the sheet and the pcb. The key section has a long flat moulded part that

pushes the 2 together when screwed down, so I stuck some insulating tape over that for added pressure.

Put it back together and completely amazed when all keys tested ok.

 

Hope this helps someone at some time, and again, sorry about the lack of photos.

Edited March 6, 2014 by Imperious

[+OLD CS1]

 

 

I successfully unlocked multiplier adjustents on my AMD Duron processor by joining the bridges with carbon from a Pencil.

 

Those were the days, brother! Good write-up. I have had success using lower-number graphite pencils (#1, #2, #3) on a bunch of projects. The repair on remote controls, however, is usually very short-lived.

[Imperious]

 

Those were the days, brother! Good write-up. I have had success using lower-number graphite pencils (#1, #2, #3) on a bunch of projects. The repair on remote controls, however, is usually very short-lived.

 

Thanks mate. I can offer a fairly good fix for remote controls. Get a paper hole punch, the type used for fitting paper sheets in a binder. Punch out some holes from Aluminum foil, trim to size if need be, then

super glue them to the pads on the flexible rubber part. I have fixed a few gamepads and remote controls doing that.

[unhuman]

They make conductive paint for this exact purpose. I bought some from Harbor Freight (I think) in anticipation of need. It worked by scaring away the problem. Never used it.