[comp.sys.atari.8bit] Flakey 130XE keyboard

rac@sherpa.UUCP (Roger Cornelius) (08/23/90)

A friend has a 130XE with a flakey keyboard.  The symptoms are:

Anywhere from 5 - 15 minutes after powering on, the keyboard stops
working, but not completely.  You just have to press very hard to get
the keys to register.

Powering off then back on has no effect if the power-on is immediate.
The unit must remain off for awhile to have any effact.

This sounds sorta like a heat problem and sorta like a mechanical
problem.  Does anyone have any suggestions for him.

Thanks.

-- 
Roger A. Cornelius          rac@sherpa.UUCP         uunet!sherpa!rac

DAVISM@kcgl1.eng.ohio-state.edu (Michael T. Davis) (08/23/90)

In article <306@sherpa.UUCP>, rac@sherpa.UUCP (Roger Cornelius) writes:

>A friend has a 130XE with a flakey keyboard.  The symptoms are:
>
>Anywhere from 5 - 15 minutes after powering on, the keyboard stops
>working, but not completely.  You just have to press very hard to get
>the keys to register.
>
>Powering off then back on has no effect if the power-on is immediate.
>The unit must remain off for awhile to have any effact.
>
>This sounds sorta like a heat problem and sorta like a mechanical
>problem.  Does anyone have any suggestions for him.
>
	It sounds like you are slowly frying your keyboard.  When I had my
130XE, I too went crazy trying to figure out what was wrong.  First step...
open your computer (warranty -- we don't need no stinking warranty ;-).  Care-
fully pull the "ribbon" from the keyboard connection on the motherboard.  Clean
the runs with a soft cloth (e.g. paper towel) with a solution of mild soap and
water.  (I used Ivory dish washing liquid.)  Rinse the runs and dry them.  Now
find R95 on the motherboard (somewhere near the keyboard connector).  In some
models, Atari in its infinite wisdom (yeah, right :-) chose to use a resistor
of smaller value than really required.  Thus more current gets through than
should normally be allowed through runs of conductive paint.  Unfortunately, I
don't remember the value of the resistor I used to replace R95.  Try 1K and
see what happens.  You want something at least twice the resistance of the
existing resistor (220 Ohms), but not so strong that you can no longer see the
power LED.
>Thanks.
>
							Good luck,
							   Mike
>--
>Roger A. Cornelius          rac@sherpa.UUCP         uunet!sherpa!rac

    davism@kcgl1.eng.ohio-state.edu    |      These Thoughts, They Be Mine
    davis-m@eng.ohio-state.edu         |

scott@tab29.larc.nasa.gov (Scott Yelich) (08/23/90)

>This sounds sorta like a heat problem and sorta like a mechanical
>problem.  Does anyone have any suggestions for him.

One of my old XEs had this problem.  (I guess it just comes from
normal use.)

I took my keyboard apart and cleaned the rubber key things (They look
like the letter Y).  I guess they get dusty.  Again, I don't know why
the keys would work sometimes and not other times... but I had the
same symptoms and what I just explained fixed MY problem keyboard.

I also had a problem with the little plastic sheet with the current
lines on it eventually cracking in certain places.  I didn't want to
solder the thing because I was afraid the heat would actually MELT
AWAY more of the plastic.

I eventually just cut a paperclip (small paperclip) to get about a
1/4" section and then I just stuck that on top of where the gap was.
I guess any open wire would work.

My main problem was blowing the PIA chip by getting sloppy while
making gadgets hardware devices to plug into the joystick ports.
It's amazing what nifty things you think of when you have 8 8bit
computers... most with 4 joystick ports!
--
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