Sun type 4 keyboard is reapaired (short summary).

From: Thomas Tonino (
Date: Wed Oct 19 1994 - 12:35:15 CDT

My keyboard is repaired, with help from four kind netpeople.

The consensus was that it should be easy (so was it), and to be
careful with the innards.

The problem turned out to be some dust in the keyboard 'contact'.

The procedure I used was as follows:

Open the keyboard case and unplug the internal keyboard.
Turn this over and unscrew the circuit board (I did this
slowly releasing each screw a bit).

When the board comes off, there are no parts willing to drop out!
Good so far.

The board loked corroded, but I just wiped it with a tissue and some
alcohol. I guess blowing the dust off would have been enough.

The other end of the 'contacts' are foam pads with what appears
to be metallized plastic on them. I understood to be very careful
with these, so I just blew off any dust there might be.

After reassembly (be careful with the little screws, try to get
them in the old thread) and making sure the aluminized paper
was not hitting anything of importance the keyboard worked
again as it should!

By the way the copper 'contacts' on the board were quite corroded.
I guess this does not matter too much as the keyboard seems to use
some capacitive action instead of making a real contact between
the aluminized pads and the board. The board layout implies this to me,

I want to thank everyone for their hints, which were mostly to clean
the innards. John Denune had experience with a loose cushioned pad;
luckily I didn't. Thanks to all.


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