[sebhc] H89 Power-up problems.
dkelvey at hotmail.com
Sat Jul 8 18:48:54 CDT 2006
>From: Lee Hart <leeahart at earthlink.net>
>dwight elvey wrote:
> > I recommend that once you expose the contact
> > put a film of silicon grease, such as DowCorning #4,
> > on the contacts. This will improve the contact and
> > stop the multiple keys.
>I don't think you want to have *anything* on the gold-plated contact
>surfaces. The contact pressure is very low, and the keyboard encoder
>chip already does ample debouncing.
>But, it is helpful to have lubrication on the plastic slides that the
>move up/down as you press the keys. There was lubrication from the
>factory (maybe just the plasticizer that comes in any recently molded
>plastic), but it dries up over time and the keys can bind if you push
I applied some of this particular grease to the contacts of my H89 about
12 to 15 years ago, when some of the keys were flakey. The last time I
use it, about 2 years ago when I was playing with the disk transfers,
it was working flawlessly.
It seems that every time I recommend this magic stuff, someone will
state a hypothetical reason for not using it. None of these reasons has
ever proved to be true over time. The only time I've had any problems
with it was when I put it on the ceramic switch of an electrometer.
It has slight conduction, on the order of several hundred megohms.
An open to most application but enough to be seen on an electrometer.
Cleaning it from the problem areas solved this over use and the remaining
film fixed the bad contact of the switch.
I've used it on edge connectors, lamp sockets, keyboard/pads, switch
cable connections, and IC pins. Many of these applications have been in use,
and on, for over 20 years.
It is especially good for power connectors that otherwise tend to overheat.
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