keyboard restaurations done!

Finally i have done the things: replaced the foam in the keyboard and the trimmer pots in the vertical amplifier circuit.

what i've found out later is that there are actually two types of foam used in the keyboard. the caps-lock key has a somewhat thicker piece of foam than the rest. so mine does'nt work well. it was the only one made of yellow foam, the others being green.

procedure i took:

i bought white sticky foam strips used to seal drafty windows. they come on a roll of about 6 meters with the correct thickness of 4mm and somewhat smaller than the required 1mm of the disks, but that is a advantage. no glue will peek around the corner of the disks.

after taking apart the keyboard i was looking at the 77 shiny disks with the foam on their back. actually there is another disk of clear sturdier plastick on the back on which the foam is glued. this piece is held in place on the key by four lastic hooks. poking underneath the clear disk with a very small flat screwdriver, the foam assembly pops out.

now for the rmoving of the foam.

on my keyboard the foam was still intact, although very sticky and slow. It turned out that putting all of the assemblies in cold water with a little ethanol alcohol did the trick. the foam literally fell apart into smal particels. the only thing i had to do it take one between my fingers and rub them together like cleaning contact lenses. the foam would crumble and float away, leaving two clean disks between my fingers. after doing that 77 times i took them all out and counted them... twice...

only then i throw away the dirty water.

rebuilding the assemblies i did eight at a time to keep the overview.

the foam has only one sticky side, the other side is made of the material on the back of stickers. that is a perfect working layer. with a hole-punch of 10mm i pushed round pieces out of the foam, but not the under-layer, leaving enoug space between the round pieces to have room to handle the silver top-disks. in stead of removing the round parts, i remove the in-betweens, so i have a strip of lets say eight round sticky foam pads on a strip of tape, the sticky side facing me. on this side the silver disks go.

with double sided tape, i stick the clear disks to the bottom after peeling them of the strip of tape. the double sided tape does'nt have to be round, a square piece will do, as long as it holds to the foam.

i now have 76 working key's and one that needs some thickening.

-- 

met vriendelijke groet

Simon Claessen
simski_at_email.domain.hidden


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